A uniformly narrowed pelvis leading to disproportion. By type of narrowing. Forms that are rare

The main indicator of narrowing of the pelvis is considered to be the size of the true conjugate: if it is less than 11 cm, then the pelvis is considered narrow

Complications during childbirth occur when the fetal head is disproportionately larger than the pelvic ring, which is sometimes observed with a normal pelvic size. In such cases, even with good labor activity, the advancement of the head along the birth canal may stop: the pelvis practically turns out to be narrow and functionally insufficient. If the fetal head is small, then even with a significant narrowing of the pelvis, there may not be a discrepancy between the head and the pelvis, and childbirth occurs naturally without any complications. In such cases, an anatomically narrowed pelvis turns out to be functionally sufficient.

Thus, there is a need to distinguish between two concepts: an anatomically narrow pelvis and a functionally narrow pelvis.

Functionally, or clinically, a narrow pelvis means a discrepancy (disproportion) between the fetal head and the mother's pelvis. In the literature, the terms “pelvic disproportion”, “pelvic dystocia”, “inadequate (clinically narrow) pelvis”, cephalopelvic disproportion, etc. are found.

Anatomically narrow pelvis occurs in 1.04-7.7% of cases. This scatter of indicators is explained by the lack of a unified classification of narrow pelvises and different diagnostic capabilities.

Causes. There are many reasons for the development narrow pelvis: malnutrition in childhood, rickets, cerebral palsy (CP), poliomyelitis, etc. Pelvic deformities are caused by diseases or damage to the bones and joints of the pelvis (rickets, osteomalacia, fractures, tumors, tuberculosis, congenital anomalies of the pelvis).

Pelvic abnormalities also occur as a result of spinal deformation (kyphosis, scoliosis, spondylolisthesis, coccyx deformity). Narrowing of the pelvis can be caused by diseases or deformities lower limbs(diseases and dislocation of the hip joints, atrophy and absence of legs, etc.).

Pelvic deformations are also possible as a result of damage from car and other accidents, earthquakes, etc.

During puberty, the formation of the pelvis occurs under the influence of estrogens and androgens. Estrogens stimulate the growth of the pelvis in transverse dimensions and its maturation (ossification), and androgens stimulate the growth of the skeleton and pelvis in length. One of the factors in the formation of a transversely narrowed pelvis is acceleration, leading to rapid growth of the body in length during puberty, when the increase in transverse dimensions is slowed down.

Significant psycho-emotional stress, stressful situations, taking hormones to block menstruation during intense sports (gymnastics, figure skating, etc.) in many girls causes “compensatory hyperfunction of the body,” which ultimately contributes to the formation of a transversely narrowed pelvis (resembling a male one).

In modern conditions, there has been a decrease in the number of women with an anatomically narrow pelvis and its various forms. So, if in the past the most common were generally narrowed and various types of flat pelvis, now these pathological forms are less common, and pelvis with reduced transverse dimensions are more often detected. In second place in terms of prevalence is a pelvis with a reduced size of the wide part of the pelvic cavity.

Currently, there is an increase in the percentage of so-called erased forms of a narrow pelvis, the diagnosis of which presents significant difficulties.

Classification. There is no unified classification of the forms of anatomically narrow pelvis. The classification is based either on an etiological principle or on the basis of an assessment of an anatomically narrow pelvis in terms of shape and degree of narrowing.

In our country, a classification is usually used based on the shape and degree of narrowing. In addition, there are often and rarely occurring forms of a narrow pelvis.

A. Relatively common forms of a narrow pelvis:

2. Flat pelvis:

A) simple flat pelvis;

B) flat-rachitic pelvis;

B) pelvis with a decrease in the direct size of the wide part of the cavity.

3. Generally uniformly narrowed pelvis.

B. Rarely occurring forms of a narrow pelvis:

1. Oblique and oblique pelvis.

2. Pelvis narrowed by exostoses and bone tumors due to displaced pelvic fractures.

3. Other pelvic shapes.

The Caldwell-Moloy (1933) classification is widely used abroad, taking into account the structural features of the pelvis (Fig. 17.1):

1) gynecoid (female type of pelvis);

2) android (male type);

3) anthropoid (characteristic of primates);

4) platipeloid (flat).

In addition to the indicated four “pure” forms of the pelvis, there are 14 variants of “mixed forms”. This classification implies the characteristics of the anterior and posterior segments of the pelvis, which play an important role in the mechanism of labor. The plane passing through the largest transverse diameter of the pelvic inlet and the posterior edge of the ischial spines divides the pelvis into anterior and posterior segments. For different forms pelvis, the size and shape of these segments are different (see Fig. 17.1). Thus, with the gynecoid form, the posterior segment is larger than the anterior one, and its contours are rounded, the shape of the entrance to the pelvis is transverse-oval. With an anthropoid pelvis, the anterior segment is narrow, long, rounded, and the posterior segment is long, but less narrow, the shape of the entrance is longitudinal-oval. With an android pelvis, the anterior segment is also narrow, and the posterior segment is wide and flat. The shape of the entrance resembles a heart. With a platypelloid pelvis, the anterior and posterior segments are wide and flat. The entrance shape is elongated, transversely oval.

1 - gynecoid; 2 - anthropoid; 3 - android; 4 - platipeloid. A line passing through the widest part of the entrance to the pelvis divides it into anterior - anterior (A) and posterior - posterior (P) segments.

In the classification of anatomically narrow pelvises, not only structural features are important, but also the degree of narrowing of the pelvis, based on the size of the true conjugate. In this case, it is customary to distinguish between four degrees of narrowing of the pelvis:

I - true conjugate less than 11 cm and more than 9 cm;

II - true conjugate less than 9 cm and more than 7.5 cm;

III - true conjugate less than 7.5 cm and more than 6.5 cm;

IV - true conjugate less than 6.5 cm.

Pelvic narrowing of degrees III and IV usually does not occur in practice.

The modern foreign manual "Williams Obstetrics" (1997) provides the following classification of narrow pelvises:

1. Narrowing of the entrance to the pelvis.

2. Narrowing of the pelvic cavity.

3. Narrowing of the pelvic outlet.

4. General narrowing of the pelvis (combination of all narrowings).

Foreign authors consider the entrance to the pelvis as narrowed if the direct dimension is less than 10 cm, the transverse dimension is less than 12 cm and the diagonal conjugate is less than 11.5 cm. A condition in which the pelvic cavity (narrow part) with an interspinous dimension of less than 10 cm should be considered as a suspicion of a narrow pelvis, and less than 8 cm - as a narrow pelvis. Narrowing of the pelvic cavity can only be determined with pelvimetry. Narrowing of the pelvic outlet should be considered if the size between the ischial tuberosities is less than 8 cm. Narrowing of the pelvic outlet without narrowing of the cavity is rare.

Transversely narrowed pelvis (Fig. 17.2). It is characterized by a decrease in the transverse dimensions of the small pelvis by 0.6-1.0 cm or more, a relative shortening or increase in the direct size of the inlet and the narrow part of the pelvic cavity, and no changes in size between the ischial tuberosities. The entrance to the small pelvis has a round or longitudinal oval shape. The transversely narrowed pelvis is also characterized by other anatomical features: small expansion of the wings of the iliac bones and a narrow pubic arch. This pelvis resembles a male pelvis and is often observed in women with hyperandrogenism.

Based on the size of the transverse diameter of the inlet, three degrees of narrowing of the transversely narrowed pelvis are distinguished.

I - 12.4-11.5 cm;

II - 11.4-10.5 cm;

III - less than 10.5 cm.

In the diagnosis of a transversely narrowed pelvis, the greatest importance is to determine the transverse diameter of the sacral rhombus (less than 10 cm) and the transverse diameter of the pelvic outlet (less than 10.5 cm). During vaginal examination, convergence of the ischial spines and an acute pubic angle are noted. Accurate diagnosis of this form of the pelvis and especially the degree of its narrowing is possible only using X-ray pelvimetry, computer X-ray pelvimetry, and magnetic resonance imaging.

Flat pelvis. In a flat pelvis, straight diameters are shortened with the usual values ​​of transverse and oblique diameters. In this case, there are three types of flat pelvis:

Simple flat basin;

Flat-rachitic pelvis;

Pelvis with a decrease in the direct diameter of the wide part of the cavity.

Simple flat basin (Fig. 17.3). It is characterized by a deeper retraction of the sacrum into the pelvis without changing the shape and curvature of the sacrum; As a result, the sacrum is moved closer than usual to the anterior wall of the pelvis and all direct dimensions of both the inlet and the cavity and outlet are moderately shortened. The curvature of the sacrum is average, the pubic arch is wide, and the transverse size of the entrance to the pelvis is usually increased. Women with a simple flat pelvis have a regular physique. With external pelvic measurement, the transverse dimensions of the pelvis are normal, and the external conjugate is reduced. Vaginal examination reveals a decrease in the diagonal conjugate.

Flat-rachitic pelvis. It differs sharply in its structure from normal (Fig. 17.4, a, b). It is a consequence of children suffering from rickets. With this disease, the ossification of the wide cartilaginous layers separating individual bone areas slows down; the cartilaginous layers thicken significantly. The amount of lime in the bones decreases. In this regard, the pressure of the spine on the pelvis and the tension of the muscular-ligamentous apparatus lead to deformation of the pelvis.

A - front view, b - sagittal section along the line of the direct size of the entrance to the pelvis.

The flat-rachitic pelvis is distinguished by the following features:

The direct size of the entrance to the pelvis is significantly shortened as a result of the deep retraction of the sacrum into the pelvis - the promontory protrudes into the pelvic cavity much more sharply than in a normal pelvis;

Sometimes a second “false” cape is observed;

The sacrum is flattened and rotated posteriorly around an axis passing across the lumbosacral joint;

The apex of the sacrum is further away from the lower edge of the articulation than in a normal pelvis;

The coccyx is often pulled in by the ischiosacral ligaments along with the last sacral vertebra anteriorly (hooked forward) (see Fig. 17.4, b).

The shape of the iliac bones changes: poorly developed, flat wings; deployed ridges due to significant wedging of the sacrum into the pelvis. The difference between distantia spinarum and distantia cristarum is either less compared to the normal pelvis, or they are equal to one another; with pronounced changes, the distance between the outer-superior spines is greater than between the scallops. The pubic arch is flatter than in a normal pelvis. The wire axis of the pelvis is not a regular arc, as is normal, but a broken line. The large and small pelvis are deformed; The direct size of the entrance is especially shortened with its normal transverse size; the promontory strongly protruding into the pelvic cavity gives the entrance plane a kidney-shaped shape; the remaining anteroposterior dimensions of the pelvic cavity are normal or enlarged; the exit dimensions are larger than usual; in some cases, the direct size of the exit is shortened due to the sharp protrusion of the coccyx at a right angle along with the last sacral vertebra.

A - front view; b - sagittal section along the line of the direct size of the entrance to the pelvis.

When diagnosing this form of the pelvis, one should pay attention to signs of rickets suffered in childhood ("square head", curvature of the legs, spine, sternum, etc.), a decrease in the vertical size of the sacral rhombus and a change in its shape (Fig. 17.5). During vaginal examination, the promontory is reachable, the sacrum is flattened and deviated posteriorly, sometimes a false promontory is identified, and the direct size of the outlet is increased.

A pelvis with a decrease in the direct size of the wide part of the pelvic cavity is characterized by flattening of the sacrum, up to the absence of curvature, an increase in its length, a decrease in the direct size of the wide part of the cavity (less than 12 cm), and the absence of a difference between the direct sizes of the inlet, the wide and narrow part of the cavity. Other sizes are usually normal or enlarged. Two degrees of narrowing should be distinguished: I degree - the direct size of the wide part of the pelvic cavity is 12.4-11.5 cm and II - the size of the cavity is less than 11.5 cm

Rice. 17.5.

; 4 - oblique.

Rice. 17.6. Generally uniformly narrowed Fig. 17.7..

To diagnose a narrow pelvis with a decrease in the direct size of the wide part of the cavity, it is informative to measure the pubosacral size - the distance from the middle of the symphysis to the place of articulation between the II and III sacral vertebrae. For an anatomically normal pelvis, the pubosacral size is 21.8 cm. A size of less than 20.5 cm indicates the presence of a narrow pelvis, and less than 19.3 cm is the basis for the assumption that there is a pronounced decrease in the direct diameter of the wide part of the pelvic cavity (less than 11.5 cm). A high correlation of the indicated pubosacral size with the size of the external conjugate was revealed.

Generally uniformly narrowed pelvis (Fig. 17.6). It is characterized by a decrease by the same amount in all dimensions of the pelvis (straight, transverse, oblique) by 1.5-2.0 cm or more.

With this type of pelvis, the sacral cavity is pronounced, the entrance to the pelvis is oval, the promontory is reached, and the pubic arch is reduced.

This type of pelvis is observed in women of small stature and regular physique. In the majority of such women, a uniformly narrowed pelvis is one of the manifestations of general infantilism that arose in childhood and during puberty. The bones of the pelvis, like the bones of the entire skeleton, are usually thin, so the pelvic cavity is quite spacious, despite the shortened external dimensions.

Diagnosis is based on data from external pelvimetry and vaginal examination. In table Figure 17.1 presents approximate data on the external dimensions of the main forms of a narrow pelvis. Oblique (asymmetrical) pelvis (Fig. 17.7) Occurs after rickets and gonitis suffered in childhood, dislocation hip joint or an improperly healed fracture of the femur or leg bones. With these diseases and the consequences of injuries, the patient steps on the healthy leg, and the torso finds support in the healthy hip joint. Gradually, the pelvic area corresponding to the healthy hip (knee) joint is pressed inward; half of the pelvis on the side of the healthy leg becomes narrower.

Table 17.1.

Rare forms of narrow pelvis

The cause of a constricted pelvis can also be scoliosis, in which the weight of the body on the limbs is distributed unevenly, as a result of which the acetabulum on the healthy side is depressed and the pelvis is deformed.

A constricted pelvis does not always impede the course of labor, since the narrowing is usually small. The narrowing of one side is compensated by the fact that the other is relatively spacious.

It is noteworthy that women in labor who have such a pelvis experience during childbirth a desire to take one or another position, which usually turns out to be the most advantageous in each specific situation.

Assimilation (“long”) pelvis. It is characterized by an increase in the height of the sacrum due to its fusion with the V lumbar vertebra (“sacralization”, “assimilation”). In this case, the direct dimensions of the pelvic cavity decrease, which can serve as an obstacle to the passage of the head through the birth canal

Funnel-shaped pelvis. Rarely encountered; its occurrence is associated with impaired development of the pelvis due to endocrine disorders. A funnel pelvis is characterized by a narrowing of the pelvic outlet. The degree of narrowing increases from top to bottom, as a result of which the pelvic cavity takes on the appearance of a funnel, tapering towards the exit.

The sacrum is elongated, the pubic arch is narrow, the transverse size of the outlet can be significantly narrowed. Childbirth can end on its own if the fetus is small and the narrowing of the pelvic outlet is not pronounced

Kyphotic pelvis Belongs to the funnel-shaped pelvis Kyphosis of the spine most often occurs as a result of tuberculous spondylitis suffered in childhood, less often rickets When a hump occurs in lower section spine, the center of gravity of the body shifts anteriorly, top part the sacrum is displaced posteriorly, the true conjugate increases, the transverse size may remain normal, the entrance to the pelvis takes on a longitudinal oval shape. The transverse size of the pelvic outlet decreases due to the convergence of the ischial tuberosities, the pubic angle is acute, the pelvic cavity narrows funnel-shaped towards the outlet. Childbirth with kyphosis often proceeds normally , if the hump is located in the upper part of the spine. The lower the hump is located and the more pronounced the pelvic deformity, the worse the prognosis for childbirth.

Spondylolisthetic pelvis This rare form of the pelvis is formed as a result of the body Ly slipping from the base of the sacrum. In the case of mild slippage, Ly protrudes only slightly above the edge of the sacrum. In case of complete slippage, the lower surface of the lumbar vertebral body covers the anterior surface of Sj and prevents the lowering of the presenting part into the small pelvis. The narrowest size of the entrance is not a true conjugate, but the distance from the symphysis to the protrusion into the pelvis Ly The prognosis of labor depends on the degree of vertebral slippage and narrowing of the direct size of the entrance to the pelvis

Osteomalactic pelvis (Fig. 178) This pathology practically does not occur in our country. Osteomalacia is characterized by softening of the bones due to decalcification of bone tissue. The pelvis is sharply deformed; with severe deformation, a collapsed pelvis is formed. The literature describes a deformation of the pelvis, characterized by a sharp transverse narrowing due to underdevelopment of the wings of the sacrum (“Robert’s pelvis")

Pelvis narrowed by exostoses and bone tumors Exostoses and bone tumors in the pelvic area are observed very rarely Exostoses can be located in the symphysis, sacral promontory and other places Tumors arising from bones and cartilage (osteosarcomas) can occupy a significant part of the pelvic cavity With significant exostoses obstructing the advancement of the presenting part of the fetus, a cesarean section is indicated. In the presence of tumors, surgical delivery and subsequent special treatment are also indicated.

Diagnosis of a narrow pelvis is carried out on the basis of anamnesis, external examination, objective examination (external pelvimetry, vaginal examination). If possible and according to indications (impossibility of assessing the size of the pelvic cavity), they are used additional methods Ultrasound studies, X-ray pelvimetry, computed tomographic pelvimetry, magnetic resonance imaging

When collecting anamnesis, attention should be paid to the presence of rickets suffered in childhood, traumatic injuries to the pelvic bones, complicated course and unfavorable outcome of previous births, surgical delivery (obstetric forceps, vacuum extraction of the fetus, cesarean section), stillbirth, traumatic brain injury in newborns , impaired neurological status in the early neonatal period, early childhood mortality

External examination is carried out first in a vertical position of the woman. First of all, body weight and height are determined. Height of 150 cm and below with certain certainty indicates an anatomical narrowing of the pelvis

Upon examination Special attention pay attention to the structure of the skeleton - traces past diseases, in which changes in bones and joints are observed (rickets, tuberculosis, etc.) They study the condition of the skull (does it have a square shape), spine (scoliosis, kyphosis, lordosis), limbs (saber-shaped curvature of the legs, shortening of one leg), joints (ankylosis in the hip, knee and other joints), gait (a waddling “duck” gait indicates excessive mobility of the joints of the pelvic bones), etc. Find out whether the abdomen has a pointed, as if pointed upward, shape in primiparous women or drooping in multiparous women (Fig. 179 ), which is typical at the end of pregnancy for women with a narrowed pelvis

Rice. 17.9.

a - in a primigravida (pointed belly), b -

In an upright position, the examinee has an idea of ​​the angle of inclination of the pelvis, the exact determination of which is possible using a pelvic angle gauge (goniometer). For practical purposes, indicative data obtained by simple examination are sufficient. When the angle of inclination of the pelvis exceeds 55°, the sacrum, buttocks and external genitalia are deviated posteriorly , there is a pronounced lordosis of the lumbar spine, the inner surfaces of the thighs do not completely touch each other. With a lower pelvic inclination angle (less than 55°), the sacrum is vertical, the symphysis pubis is raised up, the external genitalia protrude forward, there is no lordosis of the lumbar spine, and the inner surfaces of the thighs are in close contact with each other. By the degree of change in the angle of inclination of the pelvis in different positions of the pregnant woman, one can judge the mobility of the joints of the pelvis.

The shape of the sacral diamond is of great importance for assessing the pelvis. It is clearly visible if the woman’s naked back is viewed from the side.

In infantile women with a generally uniformly narrowed pelvis, the longitudinal and transverse dimensions of the rhombus are proportionally reduced.

The wider the sacrum, and therefore the larger the transverse dimensions of the pelvic cavity, the further the lateral fossae of the sacral rhombus are spaced from each other. As the transverse dimensions decrease, the distance between the lateral fossae becomes closer.

As the anteroposterior size decreases (pelvic flattening), the distance between the upper and lower corners of the diamond decreases.

With significant flattening of the pelvis, the base of the sacrum moves forward and the spinous process of the last lumbar vertebra appears at the level of the lateral fossae, as a result of which the rhombus takes the shape of a triangle, the base of which is the line connecting the lateral fossae, and the sides are the converging lines of the buttocks. With severe deformations of the pelvis, the rhombus has irregular outlines, which depend on the structural features of the pelvis and its size.

With an external obstetric examination, one can assume a narrowing of the pelvis in a situation where a high (above the entrance) position of the head of a primigravida is determined ("moving head") or when it is deviated from the entrance to the pelvis in one direction or another, which is observed with oblique and transverse fetal position.

Important information about the size of the pelvis can be obtained from external pelvimetry, although a correlation between the sizes of the large and small pelvis is not always revealed. In addition to measurements of d.spinarum, d.cristarum, d.trochanterica, conjugata externa, the lateral conjugates should be determined - the distance between the anterior and posterosuperior iliac spines on each side (normally they are 14-15 cm). Reducing them to 13 cm indicates a narrowing of the pelvis. At the same time, oblique dimensions are measured:

1) the distance from the anterosuperior spine of one side to the posterosuperior spine of the other side (normally equal to 22.5 cm);

2) the distance from the middle of the symphysis to the posterosuperior spines of the right and left iliac bones;

3) the distance from the suprasacral fossa to the anterosuperior spines on the right and left. The difference between the right and left sizes indicates asymmetry of the pelvis.

Determining the size of the pelvic outlet: direct and transverse is also important in assessing the pelvis and prognosis of childbirth.

To correctly judge the size of the true conjugate based on the diagonal conjugate data, it is necessary to take into account the height of the symphysis pubis (normally 4-5 cm). The capacity of the small pelvis largely depends on the thickness of the pelvic bones. When the circumference of the wrist joint increases above 16 cm, one should assume a greater thickness of the pelvic bones and, consequently, a decrease in the capacity of the small pelvis.

Vaginal examination is important, during which the relief of the inner surface of the pelvis should be examined in detail. Pay attention to the capacity of the pelvis (wide, narrowed pelvis), the condition of the sacrum (concave, characteristic of a normal pelvis; flat and bent posteriorly along the axis running through the articulation between the V lumbar and I sacral vertebrae in a rachitic pelvis), the presence of a coracoid or double promontory , the condition of the coccyx (the degree of its mobility, whether it is hooked anteriorly), the condition of the pubic arch (the presence of protrusions, spines and growths on the inner surface of the pubic bones, the height and curvature of the pubic arch, how narrow is the notch formed by the descending branches of the pubic bones), the condition pubic symphysis (the density of the junction of the pubic bones with each other, the mobility and width of the pubic symphysis, the presence of a dense growth on it), etc.

The main indicator of the degree of narrowing of the pelvis is the value of the true conjugate. In all cases when this is not prevented by the presenting part of the fetus descending into the pelvic cavity, it is necessary to measure the diagonal conjugate and, subtracting 1.5-2 cm, determine the length of the true conjugate.

X-ray pelvimetry allows you to determine the direct and transverse dimensions of the small pelvis in all planes, the shape and inclination of the pelvic walls, the degree of curvature and inclination of the sacrum, the shape of the pubic arch, the width of the symphysis, exostoses, deformations, the size of the fetal head, features of its structure (hydrocephalus), configuration, position heads in relation to the planes of the pelvis, etc. Modern domestic x-ray equipment (digital scanning x-ray installation) allows a 20-40-fold reduction in radiation exposure compared to film x-ray pelvimetry.

An ultrasound examination is less informative than a radiographic examination, since transabdominal scanning can only determine true conjugate, as well as the location of the fetal head, its size, features of insertion, and during childbirth - the degree of dilatation of the cervix.

Transvaginal echography allows you to measure the direct and transverse dimensions of the small pelvis.

A combination of ultrasound and X-ray pelvimetry is very informative when diagnosing a narrow pelvis.

When using magnetic resonance imaging, the accuracy of measuring the pelvis, the presenting part of the fetus, and the soft tissues of the pelvis is ensured and there is no ionizing radiation. The method is limited due to the high cost and difficulty of learning the technique.

The course and management of pregnancy with a narrow pelvis. The adverse effect of a narrowed pelvis on the course of pregnancy is felt only in its last months.

In primiparous women, due to spatial discrepancies between the pelvis and the fetal head, the latter does not enter the pelvis and can remain mobile above its entrance throughout pregnancy, until the onset of labor. The high position of the head in first-time mothers in the last months of pregnancy affects the course of pregnancy. The fetal head does not descend into the pelvis, but abdominal wall a pregnant woman is inflexible. In this regard, the growing uterus can only rise upward and, approaching the diaphragm, raises it much higher than in pregnant women with a normal pelvis. As a consequence of this, the excursion of the lungs is significantly limited and the heart is displaced. Therefore, when the pelvis is narrowed, shortness of breath at the end of pregnancy appears earlier, lasts longer and is more pronounced than during pregnancy in women with a normal pelvis.

Rice. 17.10.

(a) and anatomically narrow (b) pelvis The head stands above the entrance to the small pelvis, the anterior and posterior waters are not delimited

Rice. 17.11..

The uterus in pregnant women with a narrowed pelvis is characterized by mobility. Its bottom, due to its heaviness, easily lends itself to any movement of the pregnant woman, which, along with the high position of the head, predisposes to the formation of incorrect positions of the fetus - transverse and oblique. 25% of women in labor with established transverse and oblique position of the fetus usually have a pronounced narrowing of the pelvis to one degree or another. Breech presentation of the fetus in women in labor with a narrowed pelvis occurs three times more often than in women in labor with a normal pelvis.

A narrowed pelvis also affects the insertion of the fetal head. IN expressed cases of a pointed and drooping abdomen, moderate asynclitism, which favors the physiological course of labor, intensifies and turns into a pathological asynclitic insertion, which is a serious complication of childbirth (Fig. 17.10). The mobility of the fetal head above the narrowed entrance to the pelvis contributes to the occurrence of extensor presentations of the head (anterocephalic, frontal and facial), which relatively often complicate the course of labor with a narrowed pelvis. One of the frequent and serious complications of pregnancy with this pathology is premature rupture of amniotic fluid due to the lack of a seal. With premature rupture of amniotic fluid (before the onset of labor), cases of prolapse of umbilical cord loops are common (Fig. 17.11).

Pregnant women with a narrow pelvis are at high risk of developing complications and should be specially registered at the antenatal clinic. Timely detection of fetal position abnormalities and other complications is necessary. It is important to determine the date of birth in order to prevent post-term pregnancy, which is especially unfavorable in a narrow pelvis. 1-2 weeks before giving birth, pregnant women should be hospitalized in the pathology department to clarify the diagnosis and choose a rational method of delivery. In the presence of gestosis and other complications, the pregnant woman is sent to the maternity hospital, regardless of gestational age.

The course of labor with a narrow pelvis. The course of labor with a narrow pelvis depends primarily on the degree of narrowing of the pelvis. Thus, with I and, less often, II degrees of narrowing, medium and small fetal sizes, childbirth through the natural birth canal is possible. With II degree of pelvic narrowing, complications during childbirth are much more common than with I degree. As for the III and IV degrees of pelvic narrowing, childbirth in these cases with a live, full-term fetus is impossible.

With a narrow pelvis, early rupture of amniotic fluid is often observed due to the high position of the head and the lack of differentiation of the waters into anterior and posterior. At the moment of rupture of water, a loop of the umbilical cord or a fetal hand may fall out into the vagina. If assistance is not provided in a timely manner, the umbilical cord is pressed by the head against the pelvic wall and the fetus dies from hypoxia. The prolapsed handle reduces the volume of the narrow pelvis, creating an additional obstacle to the expulsion of the fetus

With premature and early rupture of water, the process of dilation of the cervix slows down, a birth tumor forms on the head, and uteroplacental blood flow is disrupted, which contributes to the development of hypoxia in the fetus. In the case of a long anhydrous interval, microbes from the vagina penetrate the uterine cavity and can cause endometritis during childbirth (chorioamnionitis), placentitis, and infection of the fetus.

With a narrow pelvis, labor anomalies are often observed, which manifest themselves in the form of primary and secondary weakness, discoordination. Labor becomes slow, the woman in labor becomes tired, and the fetus often experiences hypoxia.

With a narrow pelvis, a slow dilation of the cervix is ​​characteristic and at the end of the dilatation period there may be a desire to push - “false attempts”, which is caused by irritation of the cervix due to its pressing against the entrance to the pelvis.

With a narrow pelvis during the expulsion period, the head remains in all planes of the pelvis for a long time. Under the influence of labor, the head, fixed at the entrance to the pelvis, undergoes a significant configuration and at the same time adapts to the shape of the pelvis, which facilitates its passage through the birth canal. The head, fixed at the entrance to the pelvis, undergoes a significant configuration and at the same time adapts to the shape of the narrow pelvis, which and promotes its passage through the birth canal.

The period of exile. With a narrow pelvis, this period is usually prolonged: good labor is required to expel the fetus through the narrow pelvic ring. If there is a significant obstacle to expulsion, violent labor and overdistension of the lower segment of the uterus may occur, which can ultimately lead to uterine rupture. Some women in labor experience secondary weakness after violent labor ancestral forces, attempts stop and the fetus may die from hypoxia.

When the head stands for a long time at the entrance or in the pelvic cavity, compression of the soft tissues of the birth canal between the pelvic bones and the fetal head can occur. In addition to the cervix and vagina, the bladder and urethra are compressed in front, and the rectum in the back. Pressing soft tissues leads to disruption of blood circulation in them; cyanosis and swelling of the cervix, bladder wall, and subsequently of the vagina and external genitalia occur.

Due to pressure urethra and the bladder, urination stops, circulatory disorders occur and subsequently tissue necrosis. On the 5-7th day after birth, necrotic tissue can be rejected and genitourinary or rectovaginal fistulas are formed. With a generally narrowed pelvis, circular infringement of the cervix is ​​possible, which leads to its amputation. Swelling of the cervix and difficulty urinating are symptoms of significant tissue compression. An admixture of blood in the urine is a threatening sign, indicating a discrepancy and the possibility of fistula formation. The appearance of bloody discharge (even moderate) from the genital tract, frequent and painful contractions, thinning and pain in the lower segment of the uterus indicate the threat of its rupture. With a prolonged and difficult period of expulsion, compression of the nerves is possible, followed by paresis of the leg muscles. If the passage of the head through the pelvis is associated with significant difficulties, then damage to the pubic symphysis sometimes occurs, especially if the Kristeller maneuver is used during the expulsion period.

Succession period. In the afterbirth period, with a narrow pelvis, bleeding often occurs due to a violation of placental abruption. The reason for this is that when overstretched for a long time and difficult period expulsion of the uterine walls and abdominals a tired woman in labor cannot develop good afterbirth contractions and attempts necessary for physiological detachment and birth of the placenta. As a result, partial placental abruption occurs with dangerous bleeding from the uterus.

Postpartum period. In the early postpartum period, hypotonic bleeding from the uterus is often observed, since the uterus has a temporarily reduced or lost ability to contract. Bleeding from ruptures of the cervix and other tissues of the birth canal may also occur.

In the late postpartum period, postpartum infectious diseases are possible, and if labor is not managed correctly, genitourinary and intestinal fistulas, damage to the pelvic joints, etc.

Complications, threatening the fetus. Such complications often occur with a narrow pelvis. Prolonged labor and frequently observed anomalies of labor forces cause disturbances in uteroplacental blood flow and fetal hypoxia. In this case, hemorrhages in the brain and other organs of the fetus are possible. Hemorrhages in the brain intensify with sharp compression of the head and excessive displacement of the skull bones in the area of ​​the sutures. Rupture of the vessels can lead to hemorrhage under the periosteum of one or both parietal bones - cephalohematoma. With a narrow pelvis, a large birth tumor often forms, sometimes a depression (Fig. 17.12) and cracks in the bones of the skull.

Rice. 17.12..

Stillbirths, early infant mortality and morbidity with a narrow pelvis are significantly higher than with a normal pelvis.

Complications that often appear during the period of cervical dilatation, characteristic of childbirth with a narrow pelvis, are eliminated after some time by the forces of nature, and in the future childbirth proceeds physiologically. In other cases, these complications begin to emerge only

During the period of exile. Despite the fact that childbirth occurs with great difficulty, it often ends spontaneously. In such women in labor, after the opening of the uterine pharynx and the release of amniotic fluid, with good contractions and attempts, the fetal head is first pressed against the entrance to the pelvis and then fixed in it. Despite the absence of noticeable advancement of the head, it makes a slow movement, often returning to its original position again as soon as the pushing stops. The fetal head performs rotational movements, and the relative position of the fontanelles changes: the small and then the large fontanel alternately descend into the pelvis. As a result of prolonged pushing, the fetal head wedges deeper and deeper into the pelvis. Adapting, it changes its shape, more and more corresponding to the shape of the birth canal.

Thanks to the asynclitic insertion, the parietal bones protrude into the pelvic cavity to varying degrees, so one of them, at the site of the sagittal suture, extends under the other. As a rule, the overlying parietal bone (posterior), delayed by the promontory, extends under the underlying one (anterior). If the overlying bone is anterior (with posterior asynclitism), then it moves under the underlying counterpressure of the symphysis pubis. Less pronounced overlap of one bone under another is observed in the area of ​​the frontal, coronal and lambdoid sutures.

This configuration of the head occurs very slowly as a result of prolonged contractions and pushing. A slight decrease in the total volume of the fetal head occurs due to the outflow of cerebrospinal fluid into the spinal canal.

If there is an obstacle to the nascent head only at the entrance to the pelvis, then the head, having passed it, will be born in the future without any special difficulties. If other parts of the pelvis are also narrowed, then the well-configured head of the fetus, under the influence of contractions and pushing, moves along the latter, performing, together with the body, the mechanism of childbirth, which is different for each form of narrowing of the pelvis.

The mechanism of birth with a narrow pelvis differs from the mechanism of birth typical of a normal pelvis and has characteristic features characteristic of the form of narrowing.

The mechanism of childbirth with a transversely narrowed pelvis. With a transversely narrowed pelvis and the absence of a significant reduction in its transverse dimensions and the average size of the fetal head, the mechanism of labor does not differ from that with a normal pelvis.

Characteristic of a transversely narrowed pelvis without increasing the direct size of the inlet is the asynclitic insertion of the head, when it is inserted in one of the oblique dimensions of the inlet plane by the anterior parietal bone, the sagittal suture is displaced posteriorly.

The bent head gradually lowers into the pelvic cavity and subsequently makes the same movements as during the normal mechanism of childbirth: internal turn(occiput to the front), extension, external rotation. The duration of labor with a transversely narrowed pelvis is longer than with a normal one. However, when a transverse narrowing of the pelvis is combined with an increase in the true conjugate and other direct dimensions of the pelvis, especially when the true conjugate is larger than the transverse size of the inlet, the head is often installed with a sagittal suture in straight size, with the back of the head in front, which is favorable for this form of narrowing of the pelvis. In this case, the head bends and lowers to the exit of the pelvis, without making an internal rotation, and then unbends (is born).

If the head is installed with a straight arrow-shaped suture and the back of the fetal head is turned posteriorly, then a rotation of the bent head by 180° can occur in the pelvic cavity (with a small head and vigorous labor), and it will erupt in the anterior view.

If the occiput of the fetus does not rotate anteriorly, a high, erect position of the head may occur and signs of clinical discrepancy may appear, which is an indication for cesarean section.

The mechanism of childbirth in a flat-rachitic pelvis. The direct size of the pelvic inlet is reduced. The difficulties arising from this are overcome as a result following features mechanism of childbirth that is adaptive in nature:

1. Prolonged standing of the head with a sagittal suture in the transverse dimension of the entrance to the pelvis. Due to the narrowing of the entrance, the head can remain in this position for several hours even with good labor.

2. Slight extension of the head, as a result of which the large fontanel is located at the same level as the small one or below it (Fig. 17.13). With this extension, the head passes through the smallest size - the true conjugate - with a small transverse size (8.5 cm). The large transverse dimension (9.5 cm) deviates to the side where there is more space. The head in this state adapts to the entrance to the pelvis also because the size of the slightly extended head (12 cm) is smaller than the transverse size of the entrance (13-13.5 cm).

3. Asynclitic insertion of the head. Anterior - non-Gel - asynclitism (anteroparietal insertion of the head) is usually observed (Fig. 17.14, a); in this case, the posterior parietal bone rests on the promontory protruding anteriorly and lingers in this place, and the anterior parietal bone gradually descends into the pelvic cavity. The sagittal suture is located closer to the promontory. In this position (the sagittal suture in the transverse dimension of the pelvis is closer to the promontory, the large fontanel is lower than the small one), the fetal head stands at the entrance to the pelvis until its configuration is strong enough. After this, the posterior parietal bone slides off the promontory, asynclitism disappears, and the head bends. Subsequently, the mechanism of labor is the same as with the anterior view of the occipital presentation (internal rotation, extension, external rotation of the head). Less commonly observed is a more unfavorable posterior one - Litzmann asynclitism (Fig. 17.14, b) (posterior parietal insertion of the head), characterized by a deeper insertion of the posterior parietal bone. Sometimes a newborn experiences an indentation on the bones of the head due to prolonged pressing against the promontory.

Rice. 17.13.

Extension of the head at the entrance to the pelvis.

Rice. 17.14..

A - asynclitic insertion of the head (anteroparietal); b - asynclitic insertion of the head (posterior-non-parietal).

The mechanism of childbirth with a simple flat pelvis. The head enters the entrance in the same way as with a flat-rachitic pelvis. Subsequently, it descends into the pelvic cavity and is born as an occipital presentation. However, often the internal rotation of the head does not occur because, along with the direct size of the entrance to the pelvis, the direct dimensions of the cavity and outlet of the pelvis are reduced. The fetal head reaches the plane of the narrow part of the pelvic cavity, sometimes even its bottom, and the sagittal suture is located in the transverse dimension of the pelvis. This feature of the labor mechanism is called low transverse position of the head. In some cases, the fetal head at the bottom of the pelvis turns with the back of the head anterior and is born independently. If the turn does not occur, complications arise (secondary weakness of labor forces, fetal asphyxia, etc.), which are an indication for surgical delivery.

The internal rotation of the head with the occiput anteriorly occurs during the transition from the wide part of the cavity to the narrow one, and the extension of the head occurs at the outlet of the pelvis. Sometimes oblique asynclitic insertion of the head is observed. Childbirth with a posterior view of the occipital presentation of the fetus contributes to the development of clinical discrepancy between the pelvis and the head.

The mechanism of childbirth with a generally uniformly narrowed pelvis. By the beginning of labor, the fetal head is in a slightly bent position above the entrance to the pelvis - with a sagittal suture above the transverse or one of the oblique dimensions. The head, fixed at the entrance, due to the pressure it experiences from the uterus, begins to bend as much as necessary to enter and then pass through the entrance to the pelvis. The first feature of the mechanism of childbirth with a uniformly narrowed pelvis is the beginning of pronounced flexion of the head at the entrance to the pelvis (Fig. 17.15, a).

Having descended into the wide part of the pelvic cavity and encountering resistance here from the walls of the pelvis, the head slowly continues its translational and flexion movement, adding another one to them - rotation.

When the head approaches the plane of the narrow part of the pelvis, it is already in a pronounced bent position; its sagittal suture is located in an oblique, and sometimes even almost straight, narrow part of the pelvic cavity. Here the fetal head encounters an obstacle from the narrowest part of the pelvis. This obstacle is overcome due to further bending of the head, which occurs during its transition from the wide to the narrow part of the pelvic cavity. Flexion becomes maximum. In this case, the small fontanel occupies a central position in the pelvic cavity - it is located on the center line of the pelvis. This sign, determined during vaginal examination, is very characteristic of maximum flexion of the head. Thanks to this bending, the head passes through the narrowest place of the pelvis with its smallest circumference, passing through the small oblique dimension.

The maximum flexion of the head, which occurs during the transition of the head from the wide part of the pelvic cavity to the narrow one, is the second feature of the mechanism of childbirth with a generally uniformly narrowed pelvis.

With a significant narrowing of the pelvis, even such a pronounced flexion of the head is not enough to overcome the narrowed birth canal. The discrepancy between the fetal head and the pelvis is compensated by a sharp configuration of the head, sometimes so strong that it extends in length towards the small fontanelle - a dolichocephalic shape of the head is formed (Fig. 17.15, b). Often the fetal head, standing with its large segment in the wide part of the pelvic cavity or slightly higher, with its lower pole is at the exit and even appears from the genital slit, which can lead to an erroneous conclusion regarding the height of the head in the pelvis.

Rice. 17.15..

A - flexion of the head at the entrance to the pelvis; b - sharp configuration of the head (dolichocephalic head).

The sharp dolichocephalic configuration of the head is the third feature of the mechanism of childbirth with a generally uniformly narrowed pelvis.

Approaching the outlet of the pelvis with a sagittal suture in its direct size, the head begins to unbend, and subsequently the birth mechanism proceeds in the same way as with a normal pelvis.

Naturally, the narrowing of the pelvis and the need for additional movement of the head - maximum flexion and its sharp configuration - require more time for the head to pass than with a normal pelvis. Therefore, childbirth in general and the period of exile in particular are long. This explains the appearance of a large birth tumor in the area of ​​the small fontanelle, which lengthens the already sharply elongated dolichocephalic head of the fetus.

Childbirth is especially unfavorable when combined with a generally uniformly narrowed pelvis with a large fetus, with extensor insertions of the head (antecephalic, facial, frontal anticipation) and a posterior view of the occipital presentation. In such cases, the head is firmly driven into the pelvis, and its further advancement is completely stopped, which requires surgical termination of labor.

A narrow pelvis in a pregnant woman is one of the most extensive topics in obstetrics. The success of childbirth in the presence of such a pathology is largely determined by the degree of education of the specialist in this matter, as well as his experience in assisting obstetric care for women suffering from this disorder.

In the presence of what anatomical parameters is the pelvis of a pregnant woman considered narrow? What types of it exist and what should a woman who has been given a similar diagnosis know? Let's take a closer look.

What is a “narrow pelvis”?

Statistics show that approximately 5% of women giving birth are diagnosed with varying degrees pelvic constriction. In order to clearly imagine all the features of this pathology, it is necessary to understand the impact that the insufficient size of some pelvic dimensions can have on the normal course of the birth process.

In the second stage of labor, when the fetus is directly expelled, the baby must pass through the pelvic cavity.

If the shape, size or configuration of some bones relative to others do not correspond to the norm, then they create an obstacle to the normal birth passage of the child, which leads to the inevitable occurrence of problems during childbirth.

The female pelvis is a bony structure consisting of four components:

• 2 pelvic bones, which are formed from the ilium, ischium and pubis;
• sacrum;
• coccyx.

All these bone elements are interconnected by cartilage tissue and ligamentous apparatus.

In women, the size and shape of the pelvis is not the same as in the stronger sex. In women it is wider, but has less depth. Such gender characteristics are explained by female reproductive function.

Conventionally, pelvic narrowing is divided into two types:

• anatomical narrowing - the size of one or more bones does not correspond to normal sizes);
• clinical (or functional) narrowing is a relative concept, which means a discrepancy between the pelvic size and the size of the fetal head.

Even in the presence of a diagnosed anatomical narrowing, not in all cases there is a clinically narrow pelvis - for example, if the fetus has a relatively small weight, or, on the contrary, an anatomically normal pelvic size may have a clinical discrepancy with the large size of the child.

Reasons for narrowing

The reasons for the development of this pathology vary depending on the type of narrowing: either it is an anatomical defect, or a discrepancy in the size of the fetus relative to the size of the birth canal.

The following factors contribute to the formation of anatomical pelvic narrowing:

• various types of reproductive dysfunctions;
• any irregularities in the menstrual cycle or the onset of menstruation too late;
• hormonal imbalance;
• infectious diseases;
• disproportionate physical activity in childhood or adolescence, as well as a poor diet.

The above factors can have a negative impact on the formation of pelvic dimensions.

Now let's talk about diseases that directly cause the occurrence of such pathology as anatomical narrowing.

These include:

• sexual infantilism (underdevelopment of the organs of the female reproductive system);
• delayed sexual development caused by various factors: neuroendocrine disorders, hereditary diseases, autoimmune processes, inflammatory diseases of an infectious nature, pituitary tumors, etc.;
• rickets (a disease predominantly of infants associated with insufficient intake of vitamin D in the body, resulting in insufficient mineralization of bone tissue);
• osteomalacia, due to which bone tissue becomes excessively flexible;
• malignant bone formations;
• various forms of curvature of the spinal column (kyphosis, lordosis, scoliosis);
• violations of the integrity of the pelvic bones due to injuries;

• congenital structural features of the body associated with a hereditary factor;
• polio;
• exostoses (benign neoplasm of osteochondral nature that forms on the surface of the bone);
• birth injuries or damage caused in utero;
• acceleration (rapid increase in body length, with a significant lag in the formation of pelvic dimensions);
• heavy psycho-emotional stress (can provoke the development of “compensatory hyperfunction of the body”, as a result of which a transversely narrowed pelvis can form);
• intensive sports in childhood and adolescence;
• violation of metabolic processes;
• insufficient or excessive production of female sex hormones;
• excess levels of male sex hormones.

Prevention or timely treatment of these pathologies reduces the risk of developing various disorders in the structure of the pelvis.

Classification

In clinical medicine, there are several classifications of anatomical pelvic narrowing. The main one is based on morphoradiological features.

Let us examine the types of such narrowings in more detail.

• Gynecoid type. Women with such a pelvic structure make up more than half of the total number of women giving birth. This type is a variant of the norm. Women built according to this type have clear gender characteristics: thin waist, wide hips, body weight and height fluctuate within the average range.

• Android type. This type of pathological narrowing occurs in every fifth woman in labor. From the name it follows that in this case the formation of the small pelvis occurs according to the male type. It is characterized by the presence of a triangular entrance and a slightly smaller exit. The owner of a similar pelvic shape has a body structure similar to a man’s: an undefined waist, massive shoulders, narrow hips, etc.

• Anthropoid type. A characteristic sign of this narrowing is that the direct size of the entrance and the transverse size are larger than normal values. Expectant mothers with a similar defect have tall, thin build, narrow hips, massive shoulders.

• Platypeloid type. This form of narrowing does not occur very often. In this case, the pelvis has a flattened shape from top to bottom. Also, the sacrum here is slightly deviated at the back. Women with this type of narrowing are tall and thin. They have poorly developed muscles and poor skin elasticity.

Types according to Krassovsky

In addition to this classification, there are varieties of narrowed pelvis “according to Krassovsky”. The following types are distinguished:

• Generally uniformly narrowed. The shape of the pelvis corresponds to the norm, but all bone sizes are reduced in equal proportions by approximately 1.5 cm. This form of narrowing is characteristic of women of average height and normal build.

• Transversely tapered (Robertovsky). This type of narrowing is characterized by a shortening of the transverse dimensions by approximately 1 cm, as well as a relative decrease or increase in the direct diameter of the entrance. This type of pelvis is found in representatives of the fair sex, built according to the male type, often suffering from hyperandrogenism - increased production of male sex hormones.

• Flat pelvis. There are the following types:

1. simple flat - in this case there is a decrease in the magnitude of the direct diameters, and the transverse diameter of the entrance, on the contrary, is greater than the clinical norm;
2. flat-rachitic - characterized by a narrowing of the direct diameter of the entrance and an increase in all other direct diameters, and the sacrum in this case has a flat shape;

• Oblique (asymmetrical). The formation of this rather rare form of narrowing occurs due to diseases suffered in childhood or adolescence or as a result of injuries, such as rickets, dislocation of the hip joint, improperly healed fracture of the femur).

• Deformation by tumors. Damage to the pelvis can be due to the occurrence of tumors, exostoses, that is, a benign growth of osteochondral tissue.

• funnel-shaped– such a violation occurs against the background of certain hormonal disorders. The main feature is the narrowing of the exit from top to bottom in the form of a funnel).

• Kyphotic. Belongs to the type of funnel-shaped. Due to the deformation of the spinal column, the center of gravity of the body shifts slightly forward.

• Spondylolisthetic. The direct size of the entrance is insufficient due to the displacement of the V lumbar vertebra from the base of the sacrum.

• Osteomalyatic. This type of narrowing develops gradually in women of reproductive age. Deformation of bone tissue due to osteomalacia leads to pronounced curvature of the pelvis. First, the spinal column is affected, after which the pathological process spreads to the pelvis, chest and limbs.

Degrees of contraction and measurements

The diagnosis of “narrow pelvis” is made by an obstetrician-gynecologist based on the results of measuring the main obstetric parameters of the pregnant woman’s pelvis.

If any of these parameters do not correspond to the indicators accepted by experts as the average statistical norm, then this will indicate a certain form of narrowing, which is perceived as pathology.

When objectively assessing the pelvis, the doctor measures the following parameters.

Lumbosacral rhombus or Michaelis rhombus

When a woman stands, this diamond becomes clearly visible in the lower back. The obstetrician measures the distance between its opposite extreme points. The distance between vertical points should normally be at least 11 cm, and between horizontal points - at least 10 cm.

Interosseous size

To determine this indicator, a woman needs to lie on the couch. In this position, the obstetrician determines the distance between the two tubercles of the ilium. Normally, this size should be at least 25 cm:

• Maximum distance between the ilia. The measurement takes place while lying on your back. The distance between the most distant points on the iliac bones is determined. This size must be at least 28 cm.

Conjugate external

To determine this indicator, a woman needs to lie on her side, while the upper leg should be straight, and the lower leg should be bent.

The obstetrician measures the distance between the apex of the Michaelis diamond and the superior nearby point of the pubic symphysis. Normally, the outer conjugate should be at least 20 cm.

Conjugate side

It is measured with the woman in a side lying position. In this case, the ends of the pelvis are applied to the anterior and posterior points of the upper zone of the ilium on the left and right. Normally, this value should not be less than 14 cm.

Conjugate true

This indicator can only be measured during a vaginal examination. At the moment, determining a true conjugate is not mandatory for all expectant mothers. Based on the measurement of this size, one can judge the degree of narrowing of the pelvic area. Normally, the true conjugate should be 11 cm.

If any of the listed indicators do not correspond to the generally accepted norm, the obstetrician diagnoses the pregnant woman with an “anatomically narrow pelvis.” Statistics show that various types of narrowing occur in 10% of women registered for pregnancy.

As already mentioned, the degree of constriction can be determined by changing the true conjugate. Experts distinguish several degrees of pelvic contraction(depending on how short the given size is), which are shown below:

• 1st degree – IS = 10 cm;
• 2nd degree – IS = 8.5 – 9.9 cm;
• 3rd degree – IS = 5 – 8.4 cm;
• 4th degree – IS = less than 5 cm.

In clinical practice, narrowing of degrees 1 and 2 is considered conditional, since there is no guarantee that such a pathological deviation will cause difficulties during pregnancy or during childbirth.

3rd and 4th degree narrowing is an uncommon occurrence in obstetric practice, usually occurring in women who have suffered serious injuries or diseases of the musculoskeletal system.

Diagnostics

An assessment of a pregnant woman’s pelvis is carried out on the day she is registered at the antenatal clinic. In order to identify possible options violations of the normal structure of the pelvis, The gynecologist must carry out the following diagnostic measures:

• taking anamnesis;
• an objective examination of the patient, which includes anthropometry, examination, measurement of pelvic dimensions and, if necessary, vaginal examination.

IN special cases the specialist may resort to additional diagnostic methods, which include ultrasound and X-ray pelviometry.

During the history taking procedure, it is necessary to pay attention to the illnesses the woman suffered and the living conditions in which she lived in childhood and adolescence. This information may indicate the cause of the disorder in the pelvic structure.

In addition, the gynecologist can obtain information that will be very useful for managing a real pregnancy - for example, when a woman has established menstrual cycle how the previous birth proceeded, whether it was complicated by any pathologies, how it ended, etc.

In addition, the gynecologist may examine the abdomen, the shape of which may also indicate some deviations from the norm.

The doctor should pay attention to the nature of gait, changes in which may indicate various types of disorders in the musculoskeletal system of a pregnant woman.

A decisive role in establishing a diagnosis is played by measuring its main dimensions using a special device - a tazometer. Its design resembles a compass with rounded ends and is used exclusively in obstetrics.

X-ray pelviometry is performed for special indications at no earlier than 37 weeks of pregnancy. This diagnostic test can also be performed during childbirth.

In this article:

When visiting a consultation for the first time to register for pregnancy, a woman is always faced with a pelvic measurement procedure. Many of them are interested in why this is necessary, but doctors’ answers are traditionally stingy and do not give full presentation about the situation. IN best case scenario a woman is faced with the concept of a narrow pelvis during pregnancy.

So why is it necessary to determine these dimensions? For a long time it was believed that during childbirth the bones diverge slightly, allowing the baby to pass out. However, it is now reliably known that the bones remain motionless all the time. Naturally, in such conditions, the size of the bones and its configuration are crucial during childbirth, and a narrow pelvis can also affect the course of pregnancy.

Anatomical narrowness

As a result of certain complications and developmental abnormalities, sometimes one or more bone sizes turn out to be 2-3 cm shorter than normal. This is exactly the situation that is implied by the phrase anatomically narrow pelvis.

This pathology occurs quite rarely, only in 5-7% of women. There are several probable causes development of this deviation, including:

• Poor nutrition, frequent infectious diseases, metabolic disorders, vitamin deficiency in childhood, at the stage of bone formation.
• Injuries, fractures, bone tumors
• Spinal deformities
• Congenital structural anomalies
• Hormonal imbalances in adolescence.

The most common and widespread reason is, sadly, the latter. Unfortunately, in adolescence it is difficult to recognize hormonal disorders due to unstable hormonal levels. In addition, people often pay attention to deviations, but do not attach any importance to them.

What external signs suggest that a woman has a narrow pelvis?

• Height less than 160 cm
• Short fingers and toes (less than foot size 36, hand length less than 16 cm)
• A combination of short stature with changes in gait, lameness, and curvature of the spine
• Menstrual irregularities

However, an anatomically narrow pelvis does not mean inevitable complications. The size is not as important as its relationship to the fetal head.

Clinical narrowness

It's time to talk about such a concept as a clinically narrow pelvis or its non-functionality. The pelvis is called clinically narrow if the baby’s head is larger than the ring of bones. This deviation is an absolute indication for caesarean section.

Please note that a pelvis with normal dimensions may also be clinically narrow. This happens if there is a large fetus, or if the ability of the child’s skull bones to change is reduced for one reason or another. Non-functionality may also be associated with a child’s disease such as hydrocephalus or dropsy. This disease is characterized by the accumulation excess liquid in the cranium, which causes the child’s head to become greatly enlarged.

If we talk about statistics, then among women with deviations in size, we can talk about clinical narrowness in 25-30% of cases; in women with a normal skeleton, such a diagnosis occurs only in 0.3% of cases. A clinically narrow pelvis can only be diagnosed during childbirth.

Diagnostic methods

The first measurement is carried out when a pregnant woman first visits her gynecologist. The doctor uses a special instrument for measurement - a pelvisometer. It is also called a gynecological caliper. It looks like a compass, the only difference being that its “legs” are slightly rounded, and a special ruler is built into the base, showing specific dimensions.

The external measurement of the large pelvis allows us to guess what the size of the small one is, since there is a certain relationship between them. However, it is still impossible to do without a vaginal examination. It allows you to approximately determine the dimensions of the small pelvis. However, when assessing the actual size, it is necessary to evaluate the thickness of the bones.

This indicator can be determined by the circumference of the radial joint of the wrist. It is also called the Solovyov index. The average value of this index is 14 cm. If in a particular case its value is greater, then, most likely, the woman generally has quite massive bones, which means that the internal dimensions will be smaller than expected.

If the doctor has doubts regarding the diagnosis, then a additional diagnostics. This could be an ultrasound or X-ray. As a safer, but more expensive method They may suggest doing an MRI. All these methods make it possible to reliably determine the required dimensions, the presence of tumors and old injuries, defects that impede the passage of the fetus through the birth canal.

Features of pregnancy

A narrow pelvis undoubtedly affects the course of pregnancy, but mainly at the very end. All of them are associated with the fact that the baby’s head does not fall for a long time. In this regard, the uterus stretches, rises, and puts more pressure on the diaphragm. This causes difficulty breathing, shortness of breath, much more pronounced than during normal pregnancy.

Another complication that can be caused by a narrow pelvis is incorrect position fetus Therefore, women with this diagnosis often undergo an ultrasound to timely determine the position of the fetus.

Due to the fact that the baby's head does not descend towards the exit of the uterus, there is a high risk of post-maturity. Which in this situation should absolutely not be allowed, because during the period of post-term the fetus continues to grow, and a large child in this situation is extremely undesirable. In this regard, it is very important to determine the duration of pregnancy as accurately as possible in order to prevent post-term pregnancy.

Features of childbirth

A woman with this diagnosis is admitted to the maternity hospital approximately 2 weeks before the expected date of birth. This is done in order to assess her condition, the condition of the fetus, and find out what position the baby is in. During this time, it is necessary to clarify the diagnosis and decide how the birth will take place.

A narrow pelvis does not mean that childbirth will necessarily take place through a caesarean section. It all depends on the degree of narrowing and the presence or absence of other complications. However, in some cases a planned caesarean section will still be prescribed, namely if:

• There is a narrowing of the III or IV degree
• There are bone tumors that may interfere with the passage of the fetus
• There is a sharp deformation as a result of injuries and various diseases
• There are ruptures of the pubic symphysis as a result of previous births

Also, indications for surgical delivery may be a combination of a narrow pelvis with the following complications:

• Chronic;
• Abnormal development of the genital organs;
• The presence of scars on the uterus;
• Age 30 years at first birth;
• Previous history of infertility.

Complications for the fetus during childbirth

In other cases, the woman will give birth herself. Unless, of course, other complications arise during the process. And there can be quite a lot of them, and most of them are associated with the fact that the fetal head does not descend to the cervix.

First of all, because of this, the division of amniotic fluid into anterior and posterior does not occur. In this regard, the water is pressed onto the amniotic sac with its entire mass. This can cause premature rupture of amniotic fluid. In some cases, the child’s limbs or umbilical cord fall out along with the water. In this case, obstetricians will try to tuck the fallen parts back in, as they greatly reduce the already narrow space. In addition, in case of umbilical cord prolapse, fetal hypoxia may develop.

Untimely discharge of amniotic fluid can lead to another complication - primary and secondary weakness of labor. Other factors contribute to this, such as a long high position of the head, difficult dilation of the cervix, and so on. All this delays labor and exhausts the woman in labor, which also affects the strength of labor.

Premature rupture of amniotic fluid, together with the increasing duration of labor, increases the risk of infection of the mother and child with various infections. Obstetricians also have to take all this into account.

It is known that during childbirth, the child’s head changes its shape somewhat due to the fact that the bones of the skull overlap each other. If there are deviations in size, then a stronger change in the shape of the head is necessary. Because of this, certain areas of the brain are affected. In particular, those that are responsible for regulating cardiac activity. As a result, the fetal heartbeat becomes slower, which also affects the breathing rhythm.

Complications for the mother during childbirth

Complications from the mother are also possible. In particular, due to compression of the soft tissues of the birth canal between the baby’s head and the mother’s bones. As a result, there is a risk of swelling of the cervix and external genitalia, as well as impaired blood supply.

When there is a sudden difficulty in the passage of the head, or if the head stops in one place for a long time, contractions can become more severe and painful, which leads to overstretching. And this, in turn, can lead to uterine rupture.

We should not forget that the uterus gets tired during a long, protracted labor. But after the end of the process, the uterus must continue contracting in order to return to its normal size. At the same time, damaged blood vessels close. Tired of prolonged contractions, the uterus may well “refuse” to work further. The result may be postpartum hemorrhage.

As a rule, complications still arise on the part of the child. Therefore, its condition and all changes are monitored especially carefully.

Management of childbirth

Managing childbirth with a narrow pelvis is not an easy task. First of all, because only after the onset of contractions and dilation of the cervix will it become finally clear whether the pelvis is functional, or whether a caesarean section cannot be avoided. And the size of the child is difficult to determine in advance. We can talk about clinical narrowness if, when the cervix is ​​fully opened, the fetal head does not descend for primiparous women within 1.5 hours, and for those giving birth again - 1 hour. However, if the condition of the fetus or mother is of concern, no one will wait for such a long time. As already mentioned, a clinically narrow pelvis is an indication for cesarean section.

Particular attention is paid to the position of the child. Even if it is positioned with the head towards the exit of the uterus, there are options for turning the head, in which clinical patency is not assessed at all.

Usually the child tilts his head forward and brings his chin to his chest. Then the occipital part, which has the smallest radius, faces the cervix. Sometimes the baby’s neck is in an unfolded state, and the head is turned towards the cervix with the frontal or facial part. In both cases, the diameter is too large to pass through the birth canal.

Given the high risk of rupture of the amniotic sac, great attention is given to its integrity. It is necessary to reduce the water-free period as much as possible to avoid infection. To do this, the woman is recommended to lie more, preferably on the side in which the baby’s head is deflected, if there is a deviation, or on the side where the baby’s back is turned, if the baby’s head is not deflected.

Dissection of the perineum is also a fairly common procedure in such births. This is done to avoid rough breaks. It is much easier for a stitch to heal on a neat cut than on a shapeless tear.

To prevent weak contractions, vitamins, glucose solution, antispasmodics, and, of course, timely pain relief are used. But they rarely resort to labor intensification, since overly energetic contractions can harm the fetus. If the above measures are not enough, a cesarean section is resorted to.

A narrow pelvis during pregnancy is not the most common phenomenon, however, it is quite serious. That is why so much attention is paid to issues of size, and not a single pregnant woman can do without measurements. Attentive attention to the issue of anatomically and clinically narrow pelvis allows many healthy babies to be born.

Watch useful video

- an obstetric concept that implies a decrease in at least one of the sizes of the female pelvis compared to the norm (anatomical narrowing) or a discrepancy between the sizes of the pelvis and the fetus (functional narrowing), which makes it difficult for the fetus to pass through the bony base of the birth canal. A narrow pelvis during childbirth often contributes to untimely discharge of water, premature placental abruption, labor anomalies, bleeding, birth injuries to the fetus and mother, and postpartum infections. The diagnosis of a narrow pelvis is made using an external examination of the pregnant woman, measuring the size of the pelvis and fetus, vaginal examination, ultrasound, and X-ray pelviometry. Managing childbirth with a narrow pelvis has its own characteristics and often requires surgical assistance.

General information

In obstetrics and gynecology, it is customary to distinguish between anatomically and functionally (clinically) narrow pelvis. An anatomically narrow pelvis is understood as a decrease in all or one of the main dimensions of the pelvis (interosseous, intertrochanteric, the distance between the distal points of the iliac crests, external conjugate) by 1.5-2 cm or more. A functionally narrow pelvis is considered to be a discrepancy between the anatomical dimensions of the mother’s pelvis and the fetal head , which creates obstacles, sometimes insurmountable, to the birth of a child. Thus, even a pelvis that is normal in anatomical dimensions can be functionally narrow (with hydrocephalus, a large fetus) or, on the contrary, an anatomically narrowed pelvis can be functionally functional (with a premature fetus or its malnutrition). Anatomically narrow pelvis is diagnosed in 1.0-7.7% of women; functionally narrow – in 0.6-1.7% of pregnant women.

Reasons for the formation of a narrow pelvis

The formation of an anatomically narrow pelvis in a woman can be due to numerous reasons. In childhood, this can be caused by congenital anomalies, cerebral palsy, malnutrition, rickets, and polio. The male (android) type of pelvis occurs in adrenogenital syndrome (congenital adrenal hyperplasia), which is also characterized by other signs of verification. Pelvic deformities can be caused by osteomalacia, tuberculosis and bone tumors, pelvic bone fractures, spinal curvature (scoliosis, kyphosis, coccyx fractures), spondylolisthesis, hip dislocation.

During puberty, the secretion of estrogens and androgens has a great influence on the formation of the pelvis. Estrogens promote the growth of the pelvis in transverse size and its ossification, androgens - the growth of the pelvis and skeleton in length. Therefore, any hormonal imbalance during puberty, leading to an imbalance in the ratio of estrogens and androgens (hypoestrogenism and hyperandrogenism), can lead to the formation of a narrow pelvis in teenage girls.

The formation of a narrow pelvis is closely related to adolescent acceleration, leading to a rapid increase in body length with a slow increase in transverse dimensions. The development of the skeletal skeleton of girls is influenced by psycho-emotional overload, stress, intense sports activities, and the use of hormones.

Classification of narrow pelvis

In obstetric practice, the classification of the narrow pelvis according to the degree of narrowing and shape is of greatest importance. In accordance with the size of the true conjugates, pelvic narrowing is distinguished into 4 degrees:

• I degree characterized by the size of the true conjugate from 11 to 9 cm
• II degree– from 8.9 to 7.5 cm
• III degree– from 7.4 to 6.5 cm
• IV degree- from 6 cm or less. Today in obstetrics one often encounters “erased” forms of a narrow pelvis, i.e. I-II degrees narrowing.

Among the most common forms Anatomically narrow pelvis is divided into transversely narrowed (45.2%), flat (simple - 13.6%, flat-rachitic - 6.5% and reduced pelvis wide part cavities - 21.8%), generally uniformly narrowed (8.5%) types. Rarely occurring forms of a narrow pelvis (in 4.4% of women) include osteomalatic, funnel-shaped, obliquely narrowed and obliquely displaced pelvis, as well as forms of the pelvis narrowed due to exostoses, bone tumors, displaced bone fractures, etc.

If you have a narrow pelvis standing for a long time the fetal head in one plane leads to compression of the pelvic organs, followed by tissue necrosis and the formation of vaginal fistulas. With the development of excessively strong labor, the risk of rupture of the perineum, vulva and vagina, and uterus increases. Violation of the biomechanism of childbirth often leads to postpartum hemorrhage and the development of lochiometra, caused by poor uterine contractility and lochial retention.

The presence of a narrow pelvis in a woman in labor almost always poses a threat to the fetus: the child may be born in a state of hypoxia or asphyxia, with impaired cerebral circulation, cranial and spinal injuries, which will require further observation by a neurologist or neurosurgeon, resuscitation, therapeutic measures and long-term rehabilitation.

Tactics of childbirth with a narrow pelvis

The duration of gestation with a narrow pelvis is on average 39 weeks. Typically, a woman is admitted to the maternity ward 2 weeks before her due date. The absolute grounds for performing a cesarean section are stages III–IV. narrow pelvis, bone tumors in the small pelvis, severe deformation of the pelvis, the presence of pelvic injuries in previous births. Indications for planned surgical delivery also include a narrow pelvis of the first degree in combination with a breech presentation, a large fetus, post-term pregnancy, a uterine scar, chronic fetal hypoxia, and a burdened obstetric and gynecological history according to the total indications.

At I-II stage. anatomically narrow pelvis in the absence of aggravating factors, childbirth is expectant with careful monitoring of dynamics, monitoring of fetal cardiotocography and phonocardiography, prevention of early rupture of membranes and fetal hypoxia. Rodostimulation is used carefully. Surgical intervention is indicated in the case of a clinically narrow pelvis with a threat of complications for the fetus and the woman in labor.

Prevention of the formation of a narrow pelvis

Prevention of the formation of an anatomically narrow pelvis begins in childhood and includes providing the growing girl with adequate nutrition, a rational regimen of rest and exercise, and moderate physical activity; prevention of injuries and deformations of the bone skeleton. If a hormonal imbalance occurs that affects the development of the bone pelvis, timely corrective therapy is necessary.

Managing pregnancy in women with a narrow pelvis requires taking into account possible risks for the mother and fetus. It is necessary to prevent post-term pregnancy; carrying out prenatal hospitalization for the purpose of further examination, clarifying the degree and form of pelvic narrowing, and developing optimal delivery tactics.

A narrow pelvis is rightfully considered one of the most difficult and complex areas in obstetrics, since this pathology is fraught with the development of various complications during childbirth, especially if they are managed incorrectly. According to statistics, anatomical narrowing of the pelvis occurs in 1–7.7%, and during childbirth such a pelvis becomes clinically narrow in 30%. The total number of all births accounts for 1.7% of clinically narrow pelvises.

The concept of “narrow pelvis”

During the pushing period, when the fetus is expelled from the uterus, it must overcome the bony ring of the birth canal, that is, the small pelvis. The pelvis consists of 4 bones: 2 pelvic bones, formed by the ilium, pubis and ischium, the sacrum and the coccyx. These bones contact each other with the help of cartilage and ligaments. In women, the pelvis, unlike in men, is wider and more voluminous, but has less depth. Normal pelvic parameters play an important role in the physiological, without complications, course of childbirth. If there are deviations in the configuration and symmetry of the pelvis and a decrease in size, the bony pelvis acts as an obstacle to overcoming the fetal head.

IN in practical terms A narrow pelvis is divided into 2 types:

anatomically narrow pelvis, which is characterized by a decrease in one/several dimensions by 2 cm or more; a clinically narrow pelvis develops when there is a discrepancy between the size of the child’s head and the anatomical size of the woman’s pelvis during childbirth (but even in the case of anatomical narrowing of the pelvis during childbirth, the occurrence of a functionally narrow pelvis is not always possible, for example, if the fetus is small in size, and vice versa, with normal anatomical indicators pelvis and a large baby, the occurrence of a clinically narrow pelvis is quite likely).

Causes

The reasons for the formation of a narrow pelvis differ in its anatomical narrowing or the occurrence of a disproportion between the size of the baby’s head and the pelvic size of the mother.

Etiology of anatomically narrowed pelvis

The following factors can provoke the formation of an anatomically narrowed pelvis:

failures in menstrual function, violation reproductive function, late onset of menstruation; neuroendocrine pathology; frequent colds and excessive physical activity in adolescence; malnutrition, severe physical labor in childhood.

Anatomical narrowing of the pelvis is caused by the following reasons:

infantilism, both general and sexual; delayed sexual development; rickets; osteomalacia, bone tuberculosis and bone tumors; pelvic bone fractures; curvature of the spine (lordosis and kyphosis, scoliosis and coccyx fractures); cerebral palsy; constitutional features and heredity; polio; exostoses and pelvic tumors; damaging factors in the antenatal period; acceleration (rapid growth of the body in length and at the same time a slowdown in the increase in transverse pelvic dimensions); stressful situations and psycho-emotional stress, which contribute to the emergence of “compensatory hyperfunction of the body”, which forms a transversely narrowed pelvis; classes professional sports(gymnastics, skiing, swimming); impaired mineral metabolism; hypo- and hyperestrogenism, excess androgens; dislocations of the hip joints.

Etiology of a functionally narrow pelvis

Disproportion in labor between the baby's head and the mother's pelvis is caused by:

anatomical narrowing of the pelvis; large size and weight of the fruit; difficulties in the configuration of the fetal cranial bones (true post-maturity); incorrect position of the unborn baby; pathological insertion of the head (asynclitism, frontal insertion, etc.); neoplasms of the uterus and ovaries; narrowing (atresia) of the vagina; presentation with the pelvic end (rare).

Childbirth complicated by a clinically narrow pelvis ends in 9–50% by caesarean section.

Narrow pelvis: varieties

There are many classifications of anatomically narrowed pelvis. Often in the obstetric literature there is a classification based on morphological and radiological characteristics:

Gynecoid type

It makes up 55% of the total number of pelvises and is a normal female-type pelvis. The body type of the expectant mother is female, she has a thin neck and waist, and her hips are quite wide, her weight and height are within the average range.

Android pelvis

It occurs in 20% and is a male-type pelvis. A woman has a masculine physique; against the background of broad shoulders and narrow hips, there is a thick neck and an undefined waist.

Anthropoid pelvis

It makes up 22% and is characteristic of primates. This form is distinguished by an increase in the direct size of the entrance and its significant excess in the transverse size. Women with such a pelvis are tall and lean, their shoulders are quite wide, their waist and hips are narrow, and their legs are elongated and thin.

Platypeloid pelvis

Its shape is similar to a flat pelvis, observed in 3% of cases. Women with a similar pelvis are tall and thin, have underdeveloped muscles and reduced skin elasticity.

Narrowed pelvis: forms

Classification of the narrow pelvis proposed by Krassovsky:

Forms that occur frequently

Generally uniformly narrowed pelvis (ORST) is the most common type and is observed in 40–50% of all pelvises; transversely narrowed pelvis (Robertovsky); flat pelvis, 37%; simple flat (Deventrovxii); flat-rachitic; pelvis with a reduced wide part of the pelvic cavity.

Forms that are rare

obliquely displaced and obliquely narrowed; pelvic deformation due to bone tumors, exostoses and fractures; other forms: generally narrowed flat; funnel-shaped; kyphotic form; spondylolisthetic form; osteomalatic; assimilation.

Degrees of narrowing

Classification based on the degree of narrowing proposed by Palmov:

According to the length of the true conjugate (norm 11 cm) and refers to ORST and flat pelvis: 1 tbsp. – less than 11 cm and not shorter than 9 cm; 2 tbsp. – indicators of true conjugate 9 – 7.5 cm; 3 tbsp. – the length of the true conjugate is 7.5 – 6.5 cm; 4 tbsp. – shorter than 6.5 cm, which is called an “absolutely narrow pelvis.” According to the transverse diameter of the entrance to the small pelvis (normal sizes are 12.5 - 13 cm) and refers to the transversely narrowed pelvis: 1 tbsp. – transverse diameter of the inlet in the range of 12.4 – 11.5; 2 tbsp. – the value of the transverse diameter of the entrance is 11.4 – 10.5; 3 tbsp. – transverse diameter is shorter than 10.5. According to the direct diameter of the wide part of the pelvic cavity (normally 12.5 cm): 1 tbsp. – diameter 12.4 – 11.5; 2 tbsp. – diameter less than 11.5.

Dimensions of anatomically narrowed pelvis of different shapes

Narrow pelvis: dimensions (table, in cm)

Diagnostics

A narrowed pelvis is assessed and diagnosed in the antenatal clinic, on the day the pregnant woman is registered. To identify a narrow pelvis during pregnancy, the doctor examines the anamnesis, conducts an objective examination, which includes anthropometry, examination of the body, palpation of the pelvic bones and uterus, measurement of the pelvis and vaginal examination. If necessary, special methods are prescribed: X-ray pelvimetry and ultrasound scanning.

Anamnesis

It is very important to pay attention to the diseases and living conditions of a pregnant woman in childhood and adolescence (rickets and poliomyelitis, osteomyelitis and bone tuberculosis, hormonal imbalance, poor nutrition and hard physical work, intense sports loads, trauma and chronic pathology). Obstetric history data are essential:

how the previous birth proceeded; why surgical delivery was performed, whether the newborn had traumatic brain injuries; whether there was stillbirth or death of the child in the neonatal period.

Objective research

Anthropometry

Low height (145 cm or less) usually indicates a narrowed pelvis. But narrowing of the pelvis (transversely narrowed) is also possible in tall women.

Evaluated: gait, physique, silhouette

It has been proven that in the case of a strong protrusion of the abdomen forward, the center of the upper half of the body shifts posteriorly in order to maintain balance, and the lower back moves forward, thereby increasing lumbar lordosis and pelvic tilt angle.

The shape of the abdomen is assessed

It is known that in a first-time pregnant woman, the elastic abdominal wall and belly take on a pointed shape. In a multiparous woman, the belly is saggy, since the head is not inserted into the entrance of the narrow pelvis at the end of the gestation period, and the uterine fundus stands high, while the uterus itself deviates from the hypochondrium upward and anteriorly.

Identification of signs of sexual infantilism or virilization. Inspection and palpation of the Michaelis rhombus

The Michaelis rhombus consists of the following anatomical structures:

above – the lower border of the 5th lumbar vertebra; below – the apex of the sacrum; on the sides - the posterior upper projections (spines) of the ilium.

Pelvic palpation

When palpating the iliac bones, their slope, contours and location are revealed. When palpating the trochanters (greater trochanters femur) it is possible to diagnose an obliquely displaced pelvis if they are deformed and stand at different levels.

Vaginal examination

Makes it possible to determine the capacity of the pelvis, examine and evaluate the shape of the sacrum, the depth of the sacral cavity, whether there are bony protrusions, deformation of the lateral pelvic walls, measure the height of the symphysis and the diagonal conjugate.

Pelvis measurement

Basic measurements:

Distantia spinarum - the segment between the anterior superior projections of the ilium. The norm is 25 – 26 cm. Distantia cristarum is the segment between the most distant places of the iliac crests. The norm is 28 - 29 cm. Distantia trohanterica is the segment between the trochanters of the femoral bones, the norm is 31 - 32 cm. External conjugate - the distance is measured that starts from the upper edge of the womb and ends with the upper corner of the Michaelis rhombus. The norm is at least 20 cm. Michaelis rhombus measurement (vertical diagonal 11 cm, horizontal diagonal 10 cm). The asymmetry of the diamond indicates a curvature of the pelvis or spinal column. Solovyov index - the circumference of the wrist is measured at the level of the prominent condyles of the forearm. Using this index, the thickness of the bones is assessed: a small index indicates thinness of the bones, and, therefore, a greater capacity of the pelvis. The norm is 14.5 – 15 cm. Determination of the pubosacral size (the segment is measured from the middle of the symphysis to the point where the 2nd and 3rd sacral vertebrae connect). The norm is 21.8 cm. The pubic angle is measured (normally 90 degrees). The height of the symphysis pubis is determined. The uterus (OB and VDM) is measured to determine the expected weight of the fetus.

Additional measurements:

measure the angle of the pelvis; measure the pelvic outlet; if pelvic asymmetry is suspected, oblique dimensions and lateral Kerner conjugate are determined.

Special research methods

X-ray pelviometry

X-ray examinations are allowed after 37 weeks and during childbirth. With its help, the structure of the pelvic walls, the shape of the inlet, the degree of inclination of the pelvic walls, features of the ischial bones, the severity of the sacral curvature, the shape and size of the pubic arch are determined. Also this method provides an opportunity to find out all the diameters of the pelvis, bone tumors and fractures, the size of the child’s head and its position in relation to the pelvic planes.

Ultrasound

Makes it possible to determine the true conjugate, the location of the head and its size, and evaluate the features of head insertion. Using a transvaginal sensor, all pelvic diameters are determined.

How to calculate true conjugate

The following methods are used:

subtract 9 from the size of the outer conjugate (normally no less than 11 cm); 1.5 - 2 cm is subtracted from the value of the diagonal conjugate (for Solovyov index values ​​of 14 - 16 cm and less, 1.5 is subtracted, in the case of the Solovyov index greater than 16, 2 is subtracted); according to the Michaelis rhombus: his vertical size corresponds to the indicator of a true conjugate; according to X-ray pelviometry; according to ultrasound examination of the pelvis.

How is pregnancy progressing?

In the first half of the gestation period, complications with a narrowed pelvis are not observed. The nature of the course of the second half of gestation is affected by the underlying disease, which led to the formation of a narrow pelvis; in addition, extragenital pathology and complications that arise (preeclampsia, intrauterine infection, and others). Pregnant girls with a narrow pelvis are characterized by:

the formation of a pointed abdomen in primiparous women and a saggy abdomen in multiparous women, which provokes asynclitic insertion of the head during childbirth; the risk of premature birth increases; excessive fetal mobility, which contributes to abnormal fetal positions, breech presentation and extensor presentation; pregnancy is often complicated by premature rupture of water due to the lack of a contact belt with a high position of the head; high position of the head due to the impossibility of its insertion into the pelvis, which causes a high position of the uterine fundus and diaphragm and leads to increased heart rate, shortness of breath and rapid fatigue.

Management of pregnant women

All expectant mothers with a narrow pelvis are specially registered with an obstetrician-gynecologist. A couple of weeks before giving birth, the woman is hospitalized in the antenatal department as planned, where the gestational age is clarified, the expected weight of the fetus is calculated, the pelvis is re-measured, the position/presentation of the fetus and its condition are clarified, and the issue of choosing a method of delivery is decided (a labor management plan is developed).

The method of delivery is determined on the basis of anamnestic data, the anatomical form of pelvic narrowing and the degree, the expected weight of the child and other complications of gestation. Childbirth by physiological means can be carried out in the case of premature pregnancy, 1st degree of contraction and normal size of the child, a mature cervix and in the absence of a burdened obstetric history.

A planned caesarean section is performed if the following indications are present:

a combination of 1 - 2 degrees of contraction and a large fetus, breech presentation, anomaly of fetal position, post-term pregnancy; “old” primiparas, the presence of stillbirth in previous births or complicated births and the birth of a fetus with a birth injury; a combination of a narrow pelvis and other obstetric pathology that requires surgical delivery; 3 – 4 degree of narrowed pelvis (rare today).

Pregnancy and pain in the pelvic bones

Pain in the pelvic bones appears after 20 weeks and is due to various reasons:

Calcium deficiency

The pain is constant and aching, not associated with movement or change in body position. It is recommended to take calcium supplements in combination with vitamin D.

Sprain of the uterine ligaments and divergence of the pelvic bones

The larger the size of the uterus, the stronger the tension of the uterine ligaments that hold it, which manifests itself in pain and discomfort when the child walks and moves. This is caused by prolactin and relaxin, under the influence of which the ligaments and pelvic cartilage swell and soften in order to “soften” the passage of the child through the bone ring. To relieve pain, you should wear a bandage.

Divergence of the symphysis pubis

Too much swelling of the symphysis ( rare pathology) is accompanied by bursting pain in the pubis, and it is also impossible to raise a straight leg in a horizontal position. This pathology is called symphysitis, which is accompanied by divergence of the symphysis pubis. Effectively surgical treatment which is carried out after childbirth.

Course of labor

Today, the tactics of childbirth with a narrow pelvis provide for a significant increase in the indications for abdominal delivery, both planned and emergency in case of complications. Conducting the birth process through the natural birth canal is a difficult task, since the outcome can be either favorable or unfavorable for the woman and child. In cases of 3-4 degrees of narrowing, the birth of a live and full-term fetus is impossible - a planned operation is performed. If the pelvis is narrowed to degrees 1 and 2, the successful completion of labor depends on the indicators of the child’s head, its ability to be configured, the nature of the insertion of the head and the intensity of labor.

What complications arise with a narrow pelvis during childbirth?

First period

During the period of opening of the uterine pharynx, childbirth can be complicated:

weakness of generic forces (10 – 38%); early discharge of amniotic fluid; prolapse of the umbilical cord/small parts of the baby; oxygen starvation of the fetus.

Second period

During the period of expulsion of the fetus, the following complications may develop:

the occurrence of secondary weakness of generic forces; intrauterine hypoxia; threat of uterine rupture; birth injury; necrosis of tissues of the birth canal with the formation of fistulas; damage to the symphysis pubis; damage to the pelvic nerve plexuses.

Third period

The last stage of labor, as well as early postpartum period are fraught with bleeding due to the prolonged course of labor and the anhydrous interval.

Management of childbirth

Today, the most reasonable tactic for childbirth with the described pathology is recognized as active expectant. Moreover, the delivery tactics must be individual and take into account not only the results of an objective examination of the woman in labor, the degree of pelvic narrowing, but also the prognosis for the woman and child. The completed birth plan should include the following items:

bed rest during contractions, which prevents the early release of water (the woman’s position should be on the side to which the back of the fetus is adjacent); prevention of weakness of labor forces; prevention of intrauterine starvation of the fetus; prevention infectious complications; identifying signs of clinical inconsistency; preventive measures for subsequent and early postpartum hemorrhage; performing a cesarean section (if indicated) with a living fetus; fetal destruction surgery in case of fetal death.

During childbirth, discharge from the genital tract (mucous, leaking water or bloody), the condition of the vulva (swelling), and urination are monitored. In case of urinary retention, catheterization of the bladder is performed, but it should be remembered that this sign may also indicate a disproportion between the pelvic sizes of the woman in labor and the baby’s head.

The most common complication of childbirth with a narrowed pelvis is premature rupture of water. If an “immature” cervix is ​​detected, then surgical delivery is performed. In the case of a “mature” cervix, labor induction is indicated (if the estimated weight of the fetus is not more than 3600 grams and there is 1 degree of narrowing).

During the period of contractions, to prevent their weakness, an energy background is created, and the woman in labor is provided with medicated sleep and rest in a timely manner. In the process of assessing the effectiveness of labor, the doctor must monitor not only the dynamics of cervical dilatation, but also how the head moves through the birth canal.

Labor stimulation should be carried out with caution, and its duration should not exceed 3 hours (if there is no effect, a caesarean section is performed). In addition, in the first period, antispasmodics are necessarily administered (every 4 hours), Nikolaev’s triad is performed (prevention of hypoxia) and antibiotics are prescribed for an increasing anhydrous interval.

The period of expulsion is complicated by the development of secondary weakness, intrauterine hypoxia of the baby, and prolonged standing of the baby's head in the birth canal provokes the formation of fistulas. Therefore, an episiotomy is performed and the bladder is emptied in a timely manner.

Disproportion of the head and pelvis of a woman in labor

The occurrence of a clinically narrow pelvis is mainly promoted by:

slight degree of narrowing and large baby; unsuccessful insertion of the head or incorrect presentation of the fetus; large fetal head with normal pelvic dimensions; abnormal forms of narrowing of the pelvis.

During childbirth, a functional assessment of the pelvis is required, which includes:

determination of the characteristics of the insertion and assessment of the biomechanism of labor in case of identified insertion; head configuration is assessed; diagnosis of a birth tumor on the soft tissues of the head, the speed of its appearance and growth; identification of signs of Vasten and Zangheimester (assessed after the rupture of water).

The signs of a clinically narrow pelvis are as follows:

the biomechanism of childbirth is disrupted, that is, it does not correspond to this type of pelvic narrowing; the fetal head does not move forward, although the uterine os is fully dilated, the waters have broken, and the contractions are of sufficient strength; the appearance of attempts when the baby’s head is pressed to the entrance to the pelvis; symptoms of compression of soft tissues and urinary tract (swelling of the cervix and vulva, urination is delayed, blood is detected in the urine); positive signs of Vasten, Zangheimester; a clinic for the threat of uterine rupture appears; protracted course of the first period; significant head configuration; early or premature rupture of water.

Vasten's sign is determined by touch (the relationship between the baby's head and the inlet of the pelvis is determined). A negative sign of Vasten is a condition when the head is inserted into the small pelvis, located below the pubic symphysis (the doctor’s palm has dropped below the pubis). Level symptom - the obstetrician’s palm lies at the level of the womb (the head and symphysis are in the same plane). A positive sign is that the doctor’s palm is located above the symphysis (the head is higher than the pubis). In the case of a negative sign, labor ends on its own (the head and pelvic dimensions correspond to each other). With symptoms equal to possible independent childbirth subject to effective labor and adequate head configuration. If the sign is positive, independent childbirth is impossible.

Kalganova proposed to distinguish 3 degrees of discrepancy between the pelvic dimensions and the baby’s head:

1 tbsp. or relative disparity

Correct insertion of the head and its good configuration are noted. The contractions are of sufficient strength and duration, but the dilation of the cervix and the advancement of the head are slowed down, in addition, the water does not leave in a timely manner. Urination is difficult, but Vasten's sign is negative. It is possible to complete labor on your own.

2 tbsp. or significant discrepancy

The biomechanism of labor and the insertion of the head do not correspond to normal, the head is sharply configured and stands in the same plane for a long time. Anomalies of labor forces (discoordination or weakness), urinary retention are added. Vasten's sign is level.

3 tbsp. or absolute inconsistency

Attempts appear prematurely against the background of a lack of forward movement of the head, despite good contractions and full opening. The birth tumor is rapidly growing, there are signs of compression of the urethra, and a clinical picture of the threat of uterine rupture appears. A positive Vasten sign is diagnosed.

The second and third degrees of discrepancy serve as an indication for immediate surgical delivery.

Case Study

A 20-year-old primiparous woman was admitted to the maternity ward with complaints of contractions lasting 2 hours. There was no outpouring of water. The condition of the woman in labor is satisfactory, pelvic dimensions: 24.5 – 26 – 29 – 20, coolant - 103 cm, height of the uterine fundus 39 cm. The fetus is located longitudinally, the head is pressed to the entrance. Auscultation: the fetal heartbeat is clear and does not suffer. Contractions of good strength and duration. The estimated weight of the child is 4000 g.

A vaginal examination revealed: the cervix is ​​smoothed, has thin and stretchable edges, dilation is 4 cm. The fluid is intact, the amniotic sac is functioning. The head is pressed to the entrance. The cape is not accessible. Diagnosis: Pregnancy 38 weeks. 1st period of the first term birth. Large fruit. Transversely narrowed pelvis of the 1st degree.

After 6 hours of active contractions, a second vaginal examination was performed: the cervix is ​​dilated to 6 cm, there is no amniotic sac. The head is pressed to the entrance by a sagittal suture in a straight size, the small fontanel anterior.

Diagnosis: Pregnancy 38 weeks. 1st period of 1st term birth. Transversely narrowed pelvis of the 1st degree. Large fruit. High straight position of the swept seam.

It was decided to end the birth surgically (incorrect insertion, narrowing of the pelvis, large fetus). The caesarean section went without complications, and a fetus weighing 4300 grams was extracted.

Obstetrician-gynecologist Anna Sozinova

Essence of the concept Causes Classification Diagnostics Signs of a clinically narrow pelvis Signs of an anatomically narrow pelvis Course of labor

Increasingly, during gynecological examinations during pregnancy, doctors say that the sizes of the female pelvis and the fetus do not correspond to each other. This interferes with the normal course of labor. Often this situation is so dangerous that the woman in labor is offered a caesarean section to avoid unwanted consequences. What is a narrow pelvis during pregnancy and how can it harm the baby?

The essence of the concept

The pelvic bones are a dense ring through which the baby's head will have to pass during birth. The problem is that this bone formation is practically inextensible. Only a slight discrepancy is possible (only half a centimeter) due to the fact that the symphysis (cartilage) softens slightly before childbirth.

At its core, the pelvis is motionless. And if the circumference of the child’s skull is larger than this bone ring, gynecologists are forced to diagnose this anatomical feature of the female skeleton and recommend a cesarean section. What could be the reason for such an unusual pathology?

According to statistics. Recently, the frequency of diagnosis of narrow pelvis has dropped compared to previous years. It is only 7%.

Causes

Most women who were diagnosed with a narrow pelvis during pregnancy believe that this is an individual feature of the structure of their skeleton, with which they were born. In fact, in 90% of cases this problem turns out to be acquired.

The main causes of a narrow pelvis include:

health problems in childhood: rickets, poor nutrition, excessive stress provoke deviations in physical development; injuries in the pelvic area: bone fractures lead to serious deformation and reduction in size; tumors in this area: osteomas narrow the gap between the bones; hormonal disorders leading to hyperandrogenism, which is characterized by broad shoulders and a masculine narrow pelvis; acceleration of girls during adolescence, which leads to a transversely narrowed pelvis; bone infections: tuberculosis, osteomyelitis, which destroy bone tissue and lead to pelvic deformities; orthopedic diseases (for example, scoliosis).

The same phenomenon is said to occur if the fetus is too large and risks not passing into the pelvic ring, even if it is of normal size.

The parameters for which pelvis is considered narrow for childbirth have long been developed in gynecology, so the doctor will answer this question after appropriate measurements and examinations. Depending on the type of pathology, a decision will be made on how the baby will be born - by caesarean section or naturally.

What's the secret? If previously a narrow pelvis was mainly anatomical feature female skeleton, today women in labor have to face this problem due to the fact that larger children are being born more often.

Classification

According to the classification, there are two types of pathology - anatomically or clinically narrow pelvis during childbirth, which differ in relation to normal values.

Anatomical

Gynecologists diagnose an anatomically narrow pelvis when there is a narrowing of the bones, which is a deviation from the average norm. It is not always an indication for a cesarean section, because the fetus may refuse to be small and pass freely through the birth canal without injury. This type of pathology has its own special classification.

By type of narrowing:

Evenly tapered. Flat. Transversely tapered.

By degree of narrowing (Litzman classification):

1st degree

If a woman is diagnosed with a narrow pelvis of the 1st degree during pregnancy, she is allowed to give birth on her own. However, the young mother and the team of doctors must be prepared for various complications labor activity. In such cases, the surgeon and anesthesiologist are usually notified to be on the safe side. Their intervention may be needed at any moment.

2nd degree

The situation is a little more complicated when a woman is diagnosed with a narrow pelvis of the 2nd degree during pregnancy: natural childbirth is allowed, but under certain conditions. Most often, you are allowed to give birth on your own if the pregnancy is premature and the fetus is not too large.

3rd degree

Natural childbirth is not possible. If a narrow pelvis of the 3rd degree is diagnosed, this is medical indication for caesarean section. The woman is hospitalized in advance (2 weeks before the cherished date), assigning her bed rest and absolute rest.

4th degree

If during pregnancy it turns out that the expectant mother has a narrow pelvis of the 4th degree, her child can only be born by caesarean section.

Clinical

If a woman in labor is of normal size, but on the eve of birth it turns out that the fetus is too large and will not be able to pass through the pelvic ring without injury, they speak of a clinically narrow pelvis. However, in subsequent pregnancies, if the child turns out to be smaller, such a diagnosis will not be made. So if there are no other indications for a cesarean section, the birth will take place naturally.

Clinically, a narrow pelvis is diagnosed only during the last months of pregnancy or even immediately before childbirth, and its classification in obstetrics has not been developed. The most common causes of a clinically narrow pelvis:

incorrect insertion of the head; large fruit size; hydrocephalus; various malformations of the child; incorrect presentation.

All these phenomena can be clarified immediately before the birth itself or already during its process. The decision must be made very quickly; the diagnosis of a clinically narrow pelvis is based on specific obstetric signs and symptoms. In this case, an emergency caesarean section is performed.

Regardless of its type, a narrow pelvis in obstetrics is regarded as a serious complication that can lead to dangerous consequences with the wrong approach. An experienced, professional doctor, at the first suspicion of this feature of the female skeleton, takes appropriate measures and controls the size of the pelvic bones throughout pregnancy so that no unforeseen situation arises during the birth of the baby. How is this pathology diagnosed?

For reference. Hydrocephalus is a dangerous and common disease, hydrocephalus in a baby, which is characterized by the huge size of its head. There is no way it will pass through the pelvic ring.

Diagnostics

Many business and most active mothers try to find out on their own how to determine whether the pelvis is narrow for childbirth, and whether they can give birth themselves at certain sizes. In fact, this cannot be done either at home or “by eye”. Diagnosis is possible only in a hospital; it is carried out exclusively by a professional doctor using a specific obstetric instrument called a pelvisometer. With its help, the following dimensions are determined:

the interspinous distance is measured between the anterior iliac (connecting the pelvis to the spine) spines (processes), normally it should be more than 25 cm; the gap between the most distant points of the iliac bones is normally more than 28 cm; the distance between the trochanters (greater) of the femurs, the desired norm is more than 30 cm; the true conjugate is measured during a vaginal examination, this is the distance between the pubic joint and the highest point (promontory) of the sacrum; it is considered normal when the obstetrician cannot reach this point; external conjugate - the gap between the suprasacral fossa, which is located in the lumbosacral region, and the upper corner of the pubic symphysis, a certain norm - more than 20 cm; Michaelis's diamond above the coccyx, in the area of ​​the sacrum, the boundaries of which are normally clearly visible, all sides are symmetrical: transverse are 10 cm, vertical - 11 cm; The Solovyov index allows you to evaluate the thickness of the bones, which can also interfere with normal childbirth - this is the circumference of the wrist, the maximum norm is no more than 14 cm.

To clarify the parameters, in rare cases, radiography is performed, but it can harm the fetus. An ultrasound examination can also help assess the size of the narrow pelvis during pregnancy. In clinical cases where this data cannot be obtained in advance, obstetricians are guided by specific signs and symptoms.

Through the pages of history. S. A. Michaelis is a German gynecologist of the 19th century, whose name is the famous sacral rhombus, which determines whether a woman can give birth on her own or not.

Signs of a clinically narrow pelvis

Immediately before birth, if a woman in labor exhibits signs of a clinically narrow pelvis, a cesarean section is recommended. These symptoms include the following pathologies and complications:

the baby’s head does not press against the pelvic bones upon entry; the biomechanism of childbirth is disrupted; amniotic fluid pour out untimely; contraction of the uterus is disrupted: weakening of its activity, incoordination, premature appearance of attempts; the cervix has already fully opened, and the advancement of the fetus has not yet begun; the head remains in the pelvic plane for too long; protracted labor; deformation of the head, birth tumor, hematomas, fetal hypoxia; problems with the bladder: pressure, urinary retention, blood in the urine; threat of uterine rupture.

If a woman has a clinically narrow pelvis and a large fetus due to at least one of these signs, the team of doctors in 98% of cases performs an emergency cesarean section to avoid death or injury to the fetus during its movement through the birth canal. This is the only correct way out of this situation, medically completely justified and recommended.

Of course, such a birth with a narrow pelvis is much more difficult than with an anatomical one, since you can prepare for the latter in advance.

On a note. Intrauterine hypoxia is oxygen starvation of the child, which can be fatal if the fetus is not removed in time.

Signs of an anatomically narrow pelvis

The main sign of an anatomically narrow pelvis is the discrepancy between its size and the standards indicated above. But there are such impatient young mothers who cannot wait for laboratory measurements and want to know in advance whether they are predisposed to such a diagnosis. There are such signs, and they usually include:

short arms (hand length - no more than 16 cm); short fingers: thumb length - no more than 6 cm, middle finger - no more than 8; small foot size: less than 36; small stature: no more than 150 cm; curvature of the spine, limbs, lameness, orthopedic diseases; pelvic injuries; complications during previous births; irregular menstrual cycle; androgenic (male type) physique.

However, do not think that if one of the listed features applies to you, this means that you have an anatomically narrow pelvis. These are indicative signs that are observed in 98% of women who were diagnosed with this during pregnancy. You just need to keep these facts in mind in order to prepare in advance for all possible consequences. And there is no need to be afraid of them: an anatomically narrow pelvis has a huge advantage over a clinical one: it allows you to prepare for childbirth in advance.

Sometimes it happens. Often, small women turn out to be much tougher than those who have more impressive sizes in terms of childbirth. They give birth to even large babies on their own.

Course of labor

Most women who have had to deal with the problem of a narrow pelvis are interested in whether it is possible to give birth on their own with this diagnosis.

In a clinical case, no, cesarean cannot be avoided, otherwise the risk of death or injury to the fetus is too great. In the anatomical case, everything will depend on the degree of pathology. The first, for example, allows the baby to be born independently, without surgical intervention. But childbirth with a narrow pelvis of the 2nd degree (and higher) in most cases ends with a cesarean section.

Here it is very important to listen to your doctor in everything: only he can recommend how to give birth in your case, taking into account all the individual parameters and sizes of the pelvis. If there is even the slightest threat that the child will suffer when passing through the pelvic ring, it is better not to insist on a natural birth. Caesarean section is the only correct way out in such a dangerous situation.

If during pregnancy a woman is diagnosed with a narrow pelvis, doctors will have to decide whether she can give birth on her own or whether she will have to have a caesarean section. To do this, a large number of studies are carried out, all kinds of bone measurements are taken to eliminate the possibility of injury to the mother or child during childbirth. The safe birth of a baby will largely depend on the professionalism of doctors and the right decision made on time.

About 5% of expectant mothers face this problem. A narrow pelvis during pregnancy often causes complications during childbirth. This is also one of the indications for a cesarean section. There are small and large pelvises. The uterus is located in the pelvic area. If its wings do not straighten, its belly takes on a pointed shape. This happens because the uterus moves forward. During labor, the baby moves around the pelvis. And if it is of insufficient size, this becomes a serious obstacle to the advancement of the fetus and a favorable outcome of childbirth. Let's look at the types and features of bearing a child with a narrow pelvis.

Types of pelvis

There are anatomically and clinically narrow pelvises. The first type is diagnosed when the size deviates from the norm by 1.5-2 cm. Anatomical shape in turn is divided into several groups:

flat; generally uniformly narrowed; transversely narrowed.

Preventing the formation of this deviation is quite problematic. The reasons for its development include:

infectious diseases; violation hormonal balance during puberty; nutritional deficiency; damage to bone tissue due to rickets, tuberculosis or polio; heavy physical activity during the formation of the skeletal system.

Clinically, a narrow pelvis is a condition in which there is a discrepancy between the size of the fetal head and the mother's pelvis. Such a deviation cannot be predicted and can only be determined during labor. In some cases, women find out about the presence of this complication after childbirth. It can develop even in expectant mothers who have not encountered the problem of a narrow pelvis during the entire period of pregnancy.

Clinically, a narrow pelvis is divided into 3 types depending on the degree of discrepancy:

relative disparity; significant discrepancy; absolute inconsistency.

The degree is determined based on such features as the placement of the head, the absence or presence of its movement, as well as the configuration feature. The reasons for this deviation are:

large size of the fetus, which can vary from 4 to 5 kg; anatomically narrow pelvis; overbearing, in which the head loses its ability to configure; tumor formations in the pelvis; extension presentation, when the head is inserted into the entrance in an extended state; pathologies of fetal development, which are characterized by an increase in the size of the head.

Degrees of narrowing

A narrow pelvis of the 1st degree during pregnancy is a phenomenon that is not an absolute indication for a cesarean section. In this case, delivery by this method is carried out in the presence of associated complications. This is a breech presentation or incorrect position of the fetus, its large size, a scar on the uterus. Natural delivery in stage 2 can lead to various complications. Therefore, in this situation, in most cases, a caesarean section is performed. An exception may be childbirth during a premature pregnancy, when the fetus is small and can pass through a narrow pelvis. In grades 3 and 4, natural delivery is impossible, and a caesarean section is performed to remove the baby. This is the only solution for such complications as deformation changes in the pelvis or bone tumors, the presence of which creates an obstacle to the movement of the child along the birth canal.

Narrow pelvis during pregnancy: how to determine

This problem is diagnosed using the following methods:

assessing the shape of the abdomen. In first-time mothers, it has a pointed appearance, in women giving birth repeatedly, it is drooping; establishing anamnesis; measuring a woman's weight and height; measurement using a tazometer; ultrasound diagnostics; radiography. But this method is used only if the above methods did not give the necessary results and the situation remains uncertain. X-rays provide an opportunity to get an idea of ​​the size of the mother's pelvis and the baby's head. When measuring, the size corresponding to the entrance to the pelvis is determined.

Using a pelvisometer, the doctor determines the distance between the greater trochanters of the thigh bones (the norm is 30 cm or more), the anterior spines ( normal indicator- over 25 cm), iliac crests (28 cm or more). The external and true conjugate are also measured. The first indicator is determined from the upper point of the pubic symphysis to the suprasacral fossa and should normally be 20 cm. To measure the true conjugate, a vaginal examination is performed, during which the distance from the upper part of the sacral bone to the pubic joint is determined.

Measurement methods also include the determination of the Michaelis rhombus. The examination is carried out in a standing position. In the lumbosacral area you can notice a diamond-shaped figure, the corners of which are located on the sides, above the coccyx and in the lumbar region along the center line. The diamond resembles a flat platform located above the sacrum bone. Its length in the longitudinal direction should normally be 11, and in the transverse direction - 10 cm. A decrease in these indicators and an asymmetrical shape indicates an abnormal structure of the pelvis.

The bones of some women are quite massive. In this case, with a narrow pelvis, the examination results may correspond to the norm. The Solovyov index, which involves measuring the circumference of the wrist, will help you get an idea of ​​the thickness of the bones. It should not exceed 14 cm.

Pregnancy, childbirth with a narrow pelvis

A narrow pelvis does not affect the bearing of a child. But the woman should be under close supervision of specialists. During the last trimester, the fetus may take an incorrect position, which causes shortness of breath in the expectant mother. Due to possible complications during childbirth, women with a narrow pelvis are at risk. They are recommended to undergo preliminary hospitalization. Specialists, carrying out careful observation, will help prevent post-maturity, conduct additional examinations to clarify the degree of narrowing and shape of the pelvis, and develop the most optimal delivery tactics.

A favorable course of labor with an anatomically narrow pelvis is possible if the baby’s head is of average size and the process itself is quite active. Under other circumstances, certain complications arise. One of them is premature rupture of amniotic fluid. Due to the narrowness of the pelvis, the child is not able to take the desired position. Its head does not fit into the pelvic area, but is located high above the entrance. As a result, the amniotic fluid is not divided into posterior and anterior, which occurs during the normal course of labor.

With the release of amniotic fluid, the baby's limbs or umbilical cord may fall out. In this situation, attempts are made to tuck the fallen parts behind the head. If this cannot be done, then the volume of the pelvis, which is already small in size, decreases. This becomes an additional obstacle to extracting the fetus. If the loop falls out, it can press against the pelvic wall, which will limit the access of oxygen to the baby and lead to his death. Umbilical cord prolapse should be considered as direct reading to a caesarean section.

The high position of the head and the mobility of the uterus become the reasons for the incorrect presentation of the baby, which can take the pelvic, oblique or transverse position. It also leads to extension of the head. With a favorable delivery, it remains in a bent state, the occipital part appears first. During extension, the face is initially born.

Early discharge of amniotic fluid and a high position of the head become the causes of slow dilatation of the cervix, excessive stretching of its lower part, and weak labor. In women giving birth for the first time, weakness develops as a result of a long labor process with a narrow pelvis. Multiparous women face a complication such as excessive stretching of the uterine muscles. The prolonged course of labor and a prolonged anhydrous period often lead to the penetration of infection into the body of the fetus and woman. Pathogenic microflora enters the uterine cavity from the vagina.

Complications include oxygen starvation of the fetus. During contractions and pushing, the bones of the head in the area of ​​the fontanel overlap each other, and it decreases. This causes excitation of the nerve centers of the child’s cardiac regulation, the heartbeat is disturbed, which, against the background of short uterine contractions, leads to oxygen deficiency. If there is a deviation in the placental-uterine circulation, hypoxia becomes more pronounced. Such births are characterized by a long course. A child experiencing oxygen deficiency during birth often experiences impaired blood flow in the brain, asphyxia, and injuries to the skull and back. Such children in the future need careful monitoring by specialists and rehabilitation.

The soft tissue in the birth canal area is compressed between the baby's head and the pelvic bones. This occurs due to the head remaining in one place for a long time. The vagina, cervix, rectum and bladder are also subject to pressure, which disrupts blood circulation in these organs and causes them to swell. Difficult advancement of the head makes contractions more intense and painful. This often leads to severe stretching of the lower uterine wall, which increases the likelihood of uterine rupture.

Due to deviations in the size of the narrow pelvis during pregnancy, the head deviates excessively towards the perineum. Since the tissue in this area is stretched, dissection is required. Otherwise, it will not be possible to avoid a rupture. Such a severe course of labor makes it difficult for the uterus to contract, which leads to bleeding in the postpartum period.

During labor, a certain amount of time is allotted to wait for the head to drop. For primiparous women, this period is 1-1.5 hours, for multiparous women – up to 60 minutes. If a clinically narrow pelvis is observed, waiting is not practiced, but a decision is immediately made to deliver via cesarean section. This situation occurs if the cervix is ​​completely open, but the head does not pass through the birth canal.

In the first and second stages of labor, an anatomical and functional assessment of the pelvis is performed. The doctor determines its shape and degree of narrowing. Functional assessment is not carried out in all cases. This procedure is abandoned if, due to an incorrectly inserted head, the impossibility of natural delivery is obvious.

The integrity of the amniotic sac must be maintained for as long as possible. To do this, the woman must observe bed rest, and when taking a supine position, lie down on the side towards which the baby’s head or back is directed. This will help the amniotic fluid descend and help retain it for as long as necessary. After the amniotic fluid is released, the vagina is examined regularly. This is necessary for the timely detection of small parts of the fetus or the umbilical cord loop and for assessing the functional capacity of the pelvis.

During labor, uterine contractions and the condition of the child are continuously monitored using cardiotocographs. A woman is introduced medical supplies, helping to improve blood flow in the uterus and placenta. To prevent the development of weak labor, vitamins are used. Medicines whose active component is glucose help increase energy potential. Antispasmodic and painkillers are also used. If the occurrence of weak activity could not be avoided, the labor process is enhanced with medication.

Conclusion

The course of labor depends on the degree of narrow pelvis during pregnancy. If this problem is present, the child takes an incorrect position, and while moving along the birth canal, he encounters obstacles. In this situation, the fetus is removed surgically. Predicting and preventing the development of a narrow pelvis is quite problematic. The only recommendation that can be given to women who are faced with such a deviation is to regularly visit their doctor and undergo all examinations. Also, don't panic. Properly chosen delivery tactics will help preserve the health of the woman and baby.

Features of pelvic size and childbirth are presented in the video:

During the period of “interesting situation”, the dimensions of the pelvis play a very important role, because the specialist, based on them, chooses delivery tactics. If the pelvis is narrow, complications may occur during childbirth. In some cases, natural childbirth is not possible at all. The only way to give birth to a child (if a narrow pelvis is diagnosed during pregnancy) is a caesarean section. What kind of pelvis do doctors consider narrow and how do they determine it? How will pregnancy proceed with this diagnosis? Let's try to find answers to all these questions.

A little bit of anatomy: the female pelvis

Every person knows perfectly well such a part of the skeleton as the pelvis. It is conventionally divided into small and large. IN large pelvis a pregnant woman's uterus and fetus are placed.

The small pelvis is the birth canal. The baby is positioned head down towards the pelvic opening at 7-8 months of pregnancy. With the onset of labor, the fetus enters the pelvis.

The birth of a baby is a rather complex process. The fetus makes various movements in order to adapt to the shapes and sizes of the passage. Before birth, the baby's head is pressed to the chest.

It then turns to the left or right side as it wedges into the pelvic opening. After this, the head makes another turn. Thus, the child, passing through the pelvis, changes the position of the head twice.

It is worth noting that the head is the largest part of the baby. Its passage along the birth canal is ensured by:

contractile movements of the uterine muscles that push the baby forward; mobility of the bones of the fetal skull, which are not completely fused and are capable of shifting slightly and thereby adapting to the size of the passage; easy movement of the pelvic bones.

The dimensions of this part of the skeleton are different for each woman. Some people's pelvis may be normal, some may be narrow, and some may be wide. Narrow variety - serious problem for pregnant women, since the process of giving birth to a child in this case is not easy.

Due to this anatomical feature, childbirth can be complicated. Women with a narrow pelvis most often give birth not naturally, but through a caesarean section.

Anatomically narrow pelvis during pregnancy

Anatomically, a narrow pelvis is considered to be that part of the skeleton, all dimensions of which (or one of them) differ from normal parameters by 1.5-2 cm. About 6.2% of pregnant women have this diagnosis. The peculiarity of the anatomical deviation is that the fetal head may not pass through the pelvic ring during childbirth. Natural childbirth is only possible if the child is very small.

A narrow pelvis may be a consequence of the influence of certain causes on the human body in childhood: frequent infectious diseases, malnutrition, lack of vitamins, hormonal disorders during puberty. The pelvis can be deformed due to bone damage due to polio, rickets, and tuberculosis.

There is a classification of the narrow pelvis by shape. The most common types are:

flat pelvis (flat rachitic; simple flat; with a reduced direct dimension of the plane of the wide part of the pelvic cavity); transversely narrowed pelvis; generally uniformly narrowed pelvis.

Rarely encountered forms include:

oblique and obliquely displaced pelvis; pelvis deformed due to fractures, tumors; other forms.

The classification based on the degree of narrowing of the pelvis is of great importance:

true conjugate more than 9 cm, but less than 11 cm - 1 degree; true conjugate more than 7 cm, but less than 9 cm - 2nd degree; true conjugate more than 5 cm, but less than 7 cm - 3rd degree; true conjugate less than 5 cm - 4th degree.

If a woman is diagnosed with 1st degree of contraction, then natural childbirth is quite possible. They are allowed under certain conditions and with 2 degrees of pelvic narrowing. The remaining varieties are always an indication for a planned caesarean section. Attempts to give birth on your own are excluded. Read more about caesarean section →

Clinically narrow pelvis during pregnancy

Experts also distinguish a clinically narrow pelvis. Its size is not smaller than normal. It has absolutely normal physiological dimensions and shape. However, the pelvis is called narrow due to the fact that the fetus is large. For this reason, the baby cannot be born naturally. Read more about which fruit is considered large →

This type of narrow pelvis is caused not only by the large size of the fetus, but also by incorrect insertion of the child’s head (the largest size). This also prevents the birth of the fetus.

Basically, this type of narrow pelvis is diagnosed during childbirth, but assumptions often arise in the last month of pregnancy. The doctor can predict the course of labor by analyzing the size of the fetus, which is detected during an ultrasound, and the size of the woman’s pelvis.

Complications that can arise during childbirth with a clinically narrow pelvis are quite difficult for both the mother and her unborn child. For example, there may be the following consequences: oxygen starvation, respiratory failure, intrauterine fetal death.

How to determine a narrow pelvis in a pregnant woman?

A narrow pelvis in a pregnant woman should be diagnosed long before birth. Women with severe narrowing 2 weeks before the expected date of birth are routinely hospitalized in the maternity ward to avoid possible complications.

How to determine a narrow pelvis? The parameters of this part of the skeleton are determined by the gynecologist during the first examination when registering at the antenatal clinic. He uses a special tool for this - pelvisometer. It looks like a compass and is equipped with a centimeter scale. The pelvis meter is designed to determine the external dimensions of the pelvis, the length of the fetus, and the size of its head.

Suspicion of a narrow pelvis may arise before examination. As a rule, in women with this anatomical feature one can notice a masculine build, short stature, small foot size, and short toes. Orthopedic diseases (scoliosis, lameness, etc.) may occur.

How is a woman examined by a gynecologist? First of all, the specialist pays attention to the Michaelis rhombus, located in the lumbosacral region. The pits above the coccyx and on the sides are its corners. The normal longitudinal size is about 11 cm, and the transverse size is 10 cm. The parameters of the rhombus, which are less than normal values, and its asymmetry indicate an abnormal structure of the female pelvis.

A gynecologist, using a tazometer, determines the following parameters:

distance between the iliac crests. The normal value is more than 28 cm; the distance between the anterior iliac spines (interspinous size). The normal parameter is more than 25 cm; the distance between the greater trochanters of the femurs. Normal value is 30 cm; the distance between the upper edge of the pubic symphysis and the suprasacral fossa (external conjugate). The normal parameter is more than 20 cm; the distance between the symphysis pubis and the promontory of the sacrum. Obstetricians call this parameter a true conjugate. Its value is determined during a vaginal examination. Normally, a gynecologist cannot reach the promontory of the sacral bone.

Some women have massive bones. Because of this, the pelvis may appear narrow even though all its parameters do not deviate from normal values. To assess bone thickness, the Solovyov index is used - the circumference of the wrist is measured. Normally, it should be no more than 14 cm. The pelvis of a pregnant woman may be narrow if the circumference of the wrist is more than 14 cm.