Biomechanism in the posterior view of occipital presentation. Moments of the biomechanism of labor in the anterior view of the occipital presentation of the fetus. Internal correct rotation of the head

During childbirth, the fetus moves towards the exit birth canal, performing translational and rotational movements. The complex of such movements is the presentation of the fetus, which largely determines the complexity of childbirth. More than 90% of cases are occipital presentation of the fetus.

Biomechanism in primiparas

According to research, in primigravidas the head moves slightly during pregnancy. The degree of this advancement depends on the ratio of the size of the fetal head and the mother's pelvis. For some, the fetus stops its movement at the entrance, and for some - already in the expanded part of the cavity. When labor begins, the head resumes its movement when the first contractions appear. If the birth canal interferes with the progress of the fetus, then the biomechanism of childbirth during front view occipital presentation occurs in the pelvic area where an obstacle is encountered. If labor proceeds normally, then the biomechanism is activated when the head passes the boundary between the wide and narrow parts of the pelvic cavity. To cope with the obstacles that have arisen, uterine contractions alone are not enough. Attempts appear, pushing the fetus along the way to the exit from the birth canal.

In most cases, the biomechanism of labor in the anterior form of occipital presentation is involved at the stage of expulsion, when the head passes into the narrow section of the pelvic cavity from the wide one, although in first-time mothers everything can begin at the moment of opening, when the fetal head is at the entrance.

During the expulsion process, the fetus and uterus are constantly interacting with each other. The fetus tries to stretch the uterus in accordance with its shape and size, but the uterus tightly covers the fetus and amniotic fluid, adapting it to its shape. As a result of such actions ovum and the entire birth canal achieve the most complete correspondence with each other. This creates the prerequisites for the expulsion of the fetus from the birth canal.

Division into moments

The biomechanism of childbirth with anterior occipital presentation is conventionally divided into four points:

• flexion of the head;
• its internal rotation;
• extension of the head;
• internal rotation of the body in combination with external rotation of the head.

Moment one

Flexion of the head is due to the fact that under the influence of intrauterine pressure cervical region the spine bends, bringing the chin closer to the chest, and lowering the back of the head down. In this case, the small fontanel is located below the large one, gradually approaching the wire line of the pelvis, and this part becomes the lowest part of the head.

The benefit of such flexion is that it gives the head the opportunity to overcome the pelvic cavity with smallest size. The straight size of the head is 12 cm, and the small oblique size, resulting from bending, is 9.5 cm. However, during the normal course of labor, the need for such strong flexion of the head does not arise: it bends as much as is necessary to pass from the wide to the narrow section of the pelvic cavity. Maximum flexion of the fetal head is required only in situations where the width of the birth canal is not sufficient to accommodate the head. This happens when the pelvis is too narrow, as well as in the case of a posterior view of the occipital presentation.

Flexion is not the only movement of the fetus at this moment in the biomechanism of childbirth. At the same moment, the head moves through the birth canal, and after the end of flexion, its internal rotation begins. So at the first moment of the biomechanism of childbirth, a combination of translational movement with flexion and rotation takes place. However, since the most pronounced movement is flexion of the head, the name of the first moment reflects this fact.

Second moment

Internal rotation of the head is a combination of its forward movement with internal rotation. It begins when the head is bent and positioned at the entrance to the pelvis.

The fetal head, moving forward in the pelvic cavity, encounters resistance to further movement and begins to rotate around the longitudinal axis. It is as if the head is being screwed into the pelvis. This occurs most often when it passes from the wide to the narrow part of the pelvic cavity. The back of the head slides along the wall of the pelvis, approaching this moment. This moment can be recorded by watching how the position of the sagittal suture changes. Before rotation, this seam is located in the small pelvis in a transverse or oblique size, and after rotation it is located in straight size. The end of the rotation of the head is marked when the sagittal suture is established in a straight dimension, and the suboccipital fossa takes a position under the pubic arch.

Moment three

Head extension. The head continues to move along the birth canal, gradually beginning to unbend. In normal childbirth, extension occurs at the pelvic outlet. The back of the head emerges from under the pubic arch, and the forehead protrudes beyond the coccyx, protruding the back and front of the perineum in the form of a dome.

The suboccipital fossa rests on the lower edge of the pubic arch. If at first the extension of the head was slow, at this stage it speeds up: the head straightens in just a few attempts. The head penetrates the vulvar ring along its small oblique size.

During the process of extension, the crown, frontal region, face and chin appear in turn from the birth canal.

Moment four

External rotation of the head with internal rotation of the body. While the head follows along the soft tissues pelvic outlet, the hangers are screwed into the pelvic canal. The energy of this rotation is received by the newborn head. At this moment, the back of the head turns towards one of the mother’s hips. The front shoulder comes out first, followed by a slight delay due to the bending of the tailbone and the back shoulder is born.

The birth of the head and shoulders sufficiently prepares the birth canal for the appearance of the rest of the body. Therefore, this stage occurs quite easily.

The considered biomechanism of childbirth with anterior occipital presentation for primiparous women is completely true for multiparous women. The only difference is that in those giving birth again, the onset of the biomechanism occurs during the period of expulsion, when the waters break.

Obstetricians' actions

In addition to biomechanism, it is necessary to use obstetric assistance during childbirth.

You can't rely on nature for everything. Even if a woman in labor has a relatively normal birth in the occipital presentation, she may need the help of an obstetrician.

• First point. Protection of the perineum, preventing premature extension. You need to hold the head with your palms, preventing movement during pushing and increasing flexion. We must strive to ensure that the bending is not maximum, but that which is genetically necessary. There is no need to intervene unless absolutely necessary. The child is usually able to adapt to the birth canal on his own. Many complications are caused by obstetric assistance during childbirth, and not by the birth itself. More often, the child is injured not from the perineum of the mother in labor, but from the hands of the midwife, who protect the perineum.
• Second point- in the absence of attempts, remove the head from the genital slit. If the head comes out with maximum pushing, it puts a lot of pressure on the genital slit.

This is the order. With the end of the attempt, the vulvar ring is gently stretched with your fingers right hand above the emerging head. The stretching is interrupted with the beginning of a new attempt.

These actions aimed at obstetric assistance must be alternated until the head approaches the genital opening with the parietal tubercles, when compression of the head increases and stretching of the perineum increases. As a result, the risk of injury to the fetal head and the woman in labor increases.

Third point- reduce the tension of the perineum as much as possible to increase the compliance of the penetrating head. The obstetrician gently applies pressure with their fingertips to the surrounding tissues. genital opening, directs them towards the perineum, which reduces its tension.

Fourth point- adjustment of pressure. The time of appearance of the parietal tubercles of the head in the genital fissure carries an increased risk of rupture of the perineum and traumatic compression of the head.

There is an equally great danger in stopping pushing completely. Breathing plays an important role in this. The mother is told to breathe deeply and often open mouth to ease the pressure. When the need arises, the woman in labor is forced to push a little. Using the method of initialization and cessation of pushing, the midwife controls the birth of the head at the most critical time.

Fifth point- appearance of shoulders and torso. After the head comes out, the woman in labor needs to push. Shoulders are usually born without the help of an obstetrician. If this does not happen, the head is grabbed by hand. The palms of the hands touch the temporomandibular areas of the fetus. The head is first pulled down until one of the shoulders appears under the pubic arch.

Next, the head is taken with the left hand and lifted up, and with the right hand the perineum is shifted from the rear shoulder, which is carefully removed. Having freed the shoulder part, lift the body up by the armpits.

In some cases, to prevent intracranial injury Perineotomy is performed if the perineum is intractable.

Complications

Although childbirth with an anterior occipital presentation typically demonstrates biomechanism, complications can occur. Strongly affects the possibility of a successful delivery. Difficult childbirth occurs if the woman in labor has a narrow pelvis. This pathology is quite rare. This is the reason for the decision to perform a planned caesarean section. There are others unfavorable factors that can complicate childbirth: a large or post-term fetus. In these cases, it is often chosen. In some cases, the need to end labor through surgery caesarean section appears only during their course.

In some pregnant women, especially primigravidas, gynecological specialists observe some advancement of the head during pregnancy. Based on a number of different reasons, but mainly on the correspondence between the sizes of the pregnant woman’s pelvis and the fetal head, this advancement ends at the entrance or in the wide part of the female pelvis. Whenever labor activity During the appearance of the first contractions, the forward movements of the fetal head resume again. Then, when the birth canal of the expectant mother interferes with such progress, the biomechanism of childbirth begins to occur in that plane female pelvis where this obstacle was encountered. In conditions normal birth This usually occurs when the fetal head transitions into narrow part from the wide part of the pelvis of a woman giving birth. To overcome the obstacle encountered in this place by the fetal head, contractions of the uterus alone are not enough. Therefore, a pregnant woman experiences attempts that significantly put pressure on the fetus precisely in the direction of its exit from the birth canal of the expectant mother.

Taking into account the above, the biomechanism of labor in those women who give birth for the first time may begin during the period of dilatation, i.e. when the fetal head is still at the entrance. However, this most often occurs during the period of exile, i.e. during the transition of the fetal head from the wide part of the small pelvis expectant mother into its narrow part.

Throughout the entire period of exile, both the fruit itself and its container constantly influence each other. Moreover, the fetus tries to stretch the birth canal and uterus according to its own shape. At this time, the birth canal strives to cover as tightly as possible not only the fetus itself, but also the posterior waters surrounding it and thus adapting the fetus according to its shape. Thanks to this kind of interaction, the shape of the fertilized egg (afterbirth, the fetus itself and the posterior waters), as well as the shape of the birth canal, gradually come into maximum possible compliance with each other. At this time, the walls of the birth canal quite tightly cover the fertilized egg, except for the lowest segment (segment) of the head, which serves as the lumen of the uterine opened pharynx. As a result of all this, conditions are created that are optimally favorable for the expulsion of the fetus from the birth canal.

Moments of the biomechanism of labor in the anterior view of the occipital presentation of the fetus

In the case of this type of fetal presentation, gynecologists and obstetricians conditionally divide the entire biomechanism of childbirth into four main points.

Point No. 1 – “flexio capitis”, that is, flexion of the head. It manifests itself in the fact that the spine in the cervical part of the fetus bends, its chin approaches the chest, the forehead lingers, and the back of the fetal head drops down. Gradually, as the back of the head of the unborn child lowers, the small fontanel is located lower in relation to the large one, gradually approaching the wire (midline) line of the pelvis, and then, finally, becomes the so-called leading part - i.e. that part of the head that is located below everything.

The benefit of this kind of bending is manifested in the fact that just such bending provides the head with the opportunity to pass in a reduced size through the woman’s small pelvis: instead of a straight size of twelve centimeters, it has a small oblique size, which is only nine and a half centimeters. However, it should be noted that under the conditions of the physiological course of labor there is absolutely no need for such maximum flexion of the fetal head: it bends as much as necessary to pass into the narrow part from the wide part of the female pelvis into its narrow part. The need to flex the fetal head to the maximum, i.e. in its establishment, oblique and small in size in a narrow part of the pelvis of a woman giving birth, it occurs exclusively when her birth canal is extremely narrow for the fetal head. This is typical not only in the case of posterior occipital presentation, but also in narrow pelvis expectant mother, etc.

Point No. 2 – “rotatio capitis internum”, i.e. internal rotation of the unborn child's head. The fetal head, as it continues its forward movement through the pelvic cavity of the woman giving birth, encountering resistance to its further advancement, begins to rotate around the longitudinal axis, figuratively speaking, as if screwing into the pelvis of the woman in labor. Rotation of the fetal head usually begins as it moves from the widest part of the female pelvis to its narrowest part. Moreover, the back of the head, which slides along the side wall of the woman’s pelvis, approaching the pubic symphysis. In this case, the anterior part of the fetal head extends to the sacrum. Movement of this type is quite easy to detect - to do this, you just need to observe changes in the position of the swept seam. This suture, which is located before the above-described rotation in the pelvis of a giving birth woman in the transverse or in one of the oblique dimensions, subsequently turns into a straight dimension. The rotation of the head ends when this suture is installed in the direct size of the exit, but the suboccipital fossa, which is located under the small fontanel, is installed under the pubic symphysis.

This rotation of the head is preparatory to the next one, i.e. 3rd, the moment of the biomechanism of childbirth - without the first two moments it would have happened with great difficulty or would not have happened at all.

Point No. 3 – “deflexio capitis”, i.e. extension of the fetal head. During this period of labor, the head continues to gradually move along the birth canal area, but in the process it begins to simultaneously unbend. Extension during the physiological course of labor occurs at the outlet of the woman’s pelvis. The back of the head of the fetus, which stands under the pubic arch, gradually emerges from under it, while the forehead of the fetus extends beyond the coccyx and protrudes dome-shaped at first back perineum, and then the front. In the process, the suboccipital fossa abuts the inferior symphysis pubis. The extension of the head of the unborn child, which until this moment occurred slowly, at this stage intensifies: with its transverse axis, the fetal head rotates around the so-called fixation point (i.e., the lower edge of the symphysis pubis), and after a few attempts it extends almost completely. The birth of the baby's head through the vulvar ring is carried out by its small oblique size.

Moment No. 4 is called “rotatio trunci internum et capitis externum”, i.e. internal rotation of the torso of the unborn child and external rotation of its head. During the extension of the fetal head, its shoulders are already located in the transverse dimension of the entrance, and may also be in one of its oblique dimensions. As the head of the unborn child follows the soft tissues of the female pelvis, its shoulders move helically along the pelvic canal - i.e. they rotate and, at the same time, move forward. Moreover, the shoulders, with their transverse angle, transform into an oblique size from transverse size, and when exiting, it also corresponds to the direct size of the female pelvis. This kind of rotation is transmitted to the newborn baby’s head. During this process, the back of his head turns to the left in the 1st position or, in the 2nd position, to the right thigh of the expectant mother. Now the baby's front shoulder goes under the pubic arch - it is born first. At the same time, the posterior one is slightly delayed by the coccyx, and then bends it and, protruding into the perineum, is born in conditions of lateral flexion of the torso over the posterior commissure.

After the birth of the baby's shoulders, the rest of his body, due to the sufficient preparedness of the birth canal by the previously born head, is released quite easily.

All of the above points (from 1st to 4th) of the biomechanism of childbirth must occur in the exact sequence. But this does not need to be understood roughly mechanically, for example, that the fetal head first only bends, then only rotates, later only unbends and finally makes only an external turn. In practice, absolutely every movement the fetus makes during childbirth is much more complicated.

Moment No. 1 of the biomechanism of childbirth, for example, is not limited to flexion of the fetal head. It is also accompanied by a forward movement to move along the birth canal; later, when the flexion ends, the internal rotation of the baby’s head begins. Consequently, moment No. 1 of the biomechanism of childbirth includes a combination of several types of movements: flexion, translation and rotation, and the most pronounced one, which determines the main nature of the movement of the fetal head during this period of time, is its flexion. Therefore, specialists refer to moment No. 1 of the biomechanism of childbirth with the term “flexion of the head.”

Moment No. 2 of the biomechanism of childbirth is a certain combination of movements of a translational and rotational nature. At the very beginning of the internal rotation, the head of the unborn child, along with this, finishes bending, and towards the end of the rotation it begins to unbend. During this period of time, of all movements of this kind, the most pronounced is the rotation of the head. Accordingly, moment No. 2 of the biomechanism of childbirth is called “internal rotation of the fetal head.”

Moment No. 3 of the biomechanism of childbirth consists of translational movements of the fetal head and its extension. But at the same time, the fetal head, almost until birth, still continues to perform internal rotation. IN this moment The most pronounced part of the biomechanism of childbirth is the extension of the fetal head, which is why obstetricians and gynecologists call this moment “extension of the head.”

Moment No. 4 of the biomechanism of childbirth consists of translational movements of the fetal head, internal rotation of its shoulders, and also external rotation of the fetal head associated with this. At this moment, the defining movement is the external rotation of the unborn child’s head, which is most easily detected - therefore moment No. 4 bears the same name.

Simultaneously with the above movements of the head, and in some situations even preceding these movements, movements of the fetal torso also occur.

Each of the rotations of the head that were listed above can be easily detected if, during childbirth, during the opening of the uterine pharynx by approximately two to three fingers, a vaginal examination of the giving birth woman is performed several times. Regarding the movements of the fetal head (translational, flexion, rotation and extension), it is possible to judge by the relative position of the small and large fontanelles, depending on the displacement of the sagittal suture from size 1 to some other size of the female pelvis, as well as by other facts that are discovered in the process of conducting a study of a woman in labor.

At the same time, quite valuable information can be obtained using the method of external examination of a woman giving birth. Systematically (i.e. every fifteen minutes), palpation of parts of the fetus (its back, forehead, back of the head, front shoulder and chin), performed as carefully as possible, as well as auscultation of the focus of the heart sounds of the unborn child, provides an opportunity to determine changes in their relative position in relation to each other. friend and in relation to the birth canal of the woman in labor - with the plane of entry of parts of the fetus into her pelvis, with the right/left, anterior/posterior wall of the uterus, etc.

It should be added that in those multiparous women who, despite previous childbirth, retained a good functional and morphological state of the muscles of the uterine cavity and abdominals(i.e. diaphragm, abdominal wall, pelvic floor) the biomechanism of labor may well begin during dilatation or at the end of pregnancy.

Obstetric practice involves the ability to deliver a woman with any type of presentation. Depending on its type, the obstetrician-gynecologist takes certain actions. So, let's learn about the intricacies of this process.

About delivery with anterior occipital presentation

The biological mechanism of childbirth is a set of movements that the fetus makes while passing through the maternal birth canal. They are flexion, extension and rotation.

Occipital presentation is the position of the fetus in the uterus in which its head is bent and the back of the head is located lowest. Obstetric practice states that births from this position of the fetus account for about 96% of all births.

The first moment birth process is flexion of the head. Wherein cervical area The fetal spine bends, its chin approaches the chest, and the back of the head drops down. The child's forehead lingers above the entrance to the pelvis. With the anterior view of the occipital presentation, the head is bent to a small oblique size. Next, in a state of moderate bending (synclitically), it is inserted into the entrance to the small pelvis.

The second moment of childbirth is the internal (correct) rotation of the fetal head. It continues its forward movement in the pelvis and overcomes the resistance caused by the shape of the birth canal. The baby's head rotates around its longitudinal axis. In this case, the back of the head approaches the pubic symphysis and slides along the side wall of the mother’s pelvis.

The third moment of childbirth is the extension of the baby's head. It then moves along the birth canal. At physiological childbirth extension of the organ occurs at the outlet of the pelvis. The suboccipital fossa rests on the bottom of the symphysis pubis. This is how a fulcrum appears. The head is fully extended within a few attempts. The back of the head, forehead, face, and chin appear through the vulvar ring.

The fourth moment of delivery is the internal rotation of the fetal shoulders and the external rotation of its head.

After the shoulders emerge from the mother's womb, the rest of the body appears due to the fact that the birth canal is prepared by the emerging head.

About the mechanism of labor in posterior occipital presentation

In practice, only in 1% of such presentations the baby is born in the posterior view. This means that its head emerges from the mother's birth canal with the back of the head facing the sacrum. The reasons for atypical delivery include changes in pelvic capacity, incompetence of the uterine muscles, and a dead or premature fetus.

The first moment of the birth process - flexion of the head - occurs in such a way that its sagittal suture is established synclitically. The organ passes through a wide area of ​​the pelvic cavity so that the leading point is a point on this suture near the large fontanelle. The second moment of delivery is the incorrect (internal) rotation of the baby's head. The swept seam rotates 45° or 90°. Thus, the small fontanel is located behind the sacrum, while the large one is located in front of the womb. The third point is the maximum flexion of the head under the lower edge of the pubic symphysis. As a result, the back of the head is born, and then the fourth moment of the birth process occurs - its extension under the influence of ancestral forces. Next, from under the womb, the baby’s forehead appears first, then his face, which is turned towards the womb. Then the biological process of childbirth occurs in exactly the same way as in the anterior view of the occipital presentation. The fifth point is external rotation of the head and internal rotation of the shoulders.

So, the biological mechanism of the birth of a baby with this type of occipital presentation includes the most difficult moment - maximum flexion of the child’s head. That is why the period of its expulsion is prolonged and requires additional stress on the woman in labor, the work of the abdominal press and the muscles of the uterus. Due to this, soft fabrics The pelvis and perineum are subjected to powerful stretching. In most cases, they are injured. The protracted process of delivery, as well as additional pressure from the birth canal, very often leads to fetal asphyxia. This occurs due to a disorder in the baby cerebral circulation.

1. TOPIC OF THE CLASS: BIOMECHANISM OF BIRTH IN ANTERIOR AND POSTERIOR TYPES OF OCCIPITAL PRESENTATION.

2. Form of organization of the educational process: practical lesson.

3. Theme meaning(relevance of the problem being studied): Knowledge of the birth clinic is necessary for choosing labor management tactics, assessing the possibility of childbirth through the natural birth canal, correct provision of obstetric care and timely diagnosis of possible complications during childbirth.

4. Learning objectives:

4.1. General goal: To teach students to justify the diagnosis during childbirth, to draw up a plan for the management of childbirth, justifying the role of the doctor in each of the periods of labor. Correctly and timely diagnose deviations from the normal course of labor.

4.2. Learning goal: The student must know the modern mechanisms and causes of labor, the biomechanisms of childbirth during occipital presentation. Explain clearly clinical course the first stage of labor, the role of the doctor in this period. Clearly explain the clinical course of the second stage of labor; clinical course of the third stage of labor, the role of the doctor in this period. Correctly substantiate the diagnosis during childbirth. The student must be able to use the techniques of internal obstetric examination and speculum examination; provide obstetric assistance during childbirth. To develop the skills of independent supervision of women in labor in the first, second and third stages of labor.

4.3. Psychological and pedagogical goal: Knowledge of the birth clinic is necessary to draw up a plan for the management of childbirth, timely diagnosis of complications and the correct provision of obstetric care. Deviations from the normal clinical course of labor can lead to complications on the part of the mother and fetus, which the doctor must promptly diagnose and eliminate.

The student must know:

what is the biomechanism of childbirth;

moments of biomechanisms of labor in anterior and posterior types of occipital presentation.

The student must be able to:

demonstrate on the pelvis and doll all the moments of the biomechanisms of childbirth with anterior and posterior types of occipital presentation;

determine, using Leopold's maneuvers, the position, position, appearance and presentation of the fetus;

determine on the phantom in which plane of the pelvis the fetal head is located.

5. Place of practical training: maternity ward, training room, methodological room.

6. Lesson equipment:

1. Tables, obstetric simulator with a doll.

2. A set of tickets to control the initial level of knowledge of students.

3. A set of tickets for monitoring the final knowledge of students.

4. Video

7. Topic content structure(chronocard, lesson plan)

8. Topic abstract(summary)

Biomechanism of childbirth- a set of movements performed by the fetus as it passes through the birth canal. Against the background of forward movement along the birth canal, the fetus performs flexion, rotation and extension movements.

Occipital presentation This is called a presentation when the fetal head is in a bent state and its lowest located area is the back of the head. Births in the occipital presentation account for about 96% of all births. With occipital presentation there can be an anterior and posterior view. The anterior view is more often observed in the first position, the posterior view in the second.

The head enters the pelvic inlet in such a way that the sagittal suture is located along the midline (along the axis of the pelvis) - at the same distance from the pubic symphysis and the promontory - synclitic (axial) insertion. In most cases, the fetal head begins to insert into the entrance in a state of moderate posterior asynclitism. Later, during the physiological course of labor, when contractions intensify, the direction of pressure on the fetus changes and, in connection with this, asynclitism is eliminated.

After the head has descended to the narrow part of the pelvic cavity, the obstacle encountered here causes an increase in labor activity, and at the same time an increase in various movements of the fetus.

Biomechanism of labor in anterior occipital presentation consists of four points.

First moment- flexion of the head. At the entrance to the pelvis, the head is in such a position that its sagittal suture coincides with the transverse size of the entrance to the pelvis. When the head is bent, the chin moves closer to the chest, and the back of the head moves down. As the back of the head lowers, the small fontanel is installed lower than the large one, gradually approaches the pelvic wire line and becomes the lowest located part of the head - wired point.

Flexion of the head allows it to pass through the pelvic cavity with its smallest size - small oblique (9.5 cm).

Second point– internal rotation of the head with the occiput anterior (correct rotation). The head, during its translational movement, simultaneously with flexion, begins to rotate around its longitudinal axis. In this case, the back of the head, sliding along the side wall of the pelvis, approaches the pubic symphysis. The sagittal suture changes from a transverse dimension to a straight one, and the suboccipital fossa is installed under the pubic symphysis.

Third point– extension of the head begins after the suboccipital fossa abuts the lower edge of the pubic symphysis, forming fixation point(hypomochlion). The head rotates around the fixation point and, with several attempts, is completely unbent and born.

Fourth point– internal rotation of the body and external rotation of the head. During extension of the head, the fetal shoulders are inserted into the transverse dimension of the entrance. Following the head, the shoulders move helically along the birth canal. With their transverse size, they move from the transverse size of the plane of entry into the small pelvis to the oblique (in the pelvic cavity), and then to the direct size in the plane of exit. This rotation is transmitted to the born head, while the back of the fetal head turns towards the left (in the first position) or right (in the second position) thigh of the mother.

Biomechanism of labor in posterior occipital presentation consists of five points.

First moment– flexion of the head in the plane of the entrance to the pelvis. The conducting point is the small fontanel.

Second point- internal rotation of the head with the back of the head. The area between the small and large fontanel becomes the wire point.

Third point– additional flexion of the head – occurs in the plane of the exit of the pelvis. A fixation point is formed, the fetal head rests against the lower edge of the symphysis with the region of the anterior edge of the large fontanel.

Fourth point- extension of the head. A fixation point is formed between the suboccipital fossa and the tip of the coccyx. The head is born facing forward. The head is cut through by a circle of medium oblique size.

Fifth moment t – internal rotation of the shoulders and external rotation of the head. The configuration of the head in the posterior view of the occipital presentation is dolichocephalic.

Causes of rear view may be caused by both the fetus (small size of the head) and the condition of the birth canal of the woman in labor (anomalies in the shape of the pelvis and pelvic floor muscles).

Features of the clinical course of labor in the posterior form of occipital presentation:

Long duration of labor.

Excessively large expenditure of labor force.

High maternal trauma (large stretching of the pelvic floor and perineum and frequent ruptures).

Fetal hypoxia, cerebrovascular accidents, cerebral lesions.

9. Self-study questions

Determination of the biomechanism of childbirth.

Biomechanism of labor in anterior occipital presentation.

Biomechanism of labor in posterior occipital presentation.

The influence of the biomechanism of labor on the shape of the head.

10. Test tasks on the topic.

1. In the anterior view of the occipital presentation, ..... moments of the biomechanism of labor are highlighted.

B) four

2. The wire point for the anterior view of the occipital presentation is ...

A) large fontanelle

B) small fontanelle

B) occipital protuberance

3. In the anterior view of the occipital presentation, the head is born ...... in size.

A) direct

B) middle oblique

B) small oblique.

4. In the second position, posterior view, the fetal face should turn towards ..... mother's thigh

A) to the right

B) to the left

B) anteriorly.

5. The skull of a newborn born in the posterior form of occipital presentation has the shape of .....

A) dolichocephalic

B) brachiocephalic

B) spherical.

6. Moments of the biomechanism of labor in the posterior view of occipital presentation….

B) four

7. The head in the posterior view of the occipital presentation is born……. size.

A) direct

B) middle oblique

B) small oblique.

8. The wire point for the posterior view of the occipital presentation is….

A) small fontanelle

B) large fontanelle

C) the middle between the small and large fontanelles.

9. The head is located in the pelvic cavity in…. moment of the biomechanism of childbirth.

A) in the first

B) in the second

B) on the third

10. When the head is located on the pelvic floor, the sagittal suture is located in……. pelvic size.

A) transversely

B) straight

B) in the left oblique.

11. Situational tasks on the topic

Task No. 1

Place the fetus in the 1st position, anterior occipital presentation. The fetal head is at the outlet of the pelvis. Confirm with appropriate vaginal examination data.

Task No. 2

Place the fetus in the 1st position, anterior occipital presentation. The fetal head is a small segment in the plane of the entrance to the pelvis. Confirm with appropriate vaginal examination data.

Task No. 3

Place the fetus in the 2nd position, anterior occipital presentation. The fetal head is a large segment in the plane of the entrance to the pelvis. Confirm with appropriate vaginal examination data.

Students are invited to speak at a conference on the topic of the lesson.

Sample speech topics:

The influence of the shape of the birth canal on the principles of the biomechanism of childbirth.

Features and reasons for the configuration of the head during labor depending on the biomechanism.

Features of the biomechanism of childbirth with pelvic anomalies.

14. List of literature on the topic of classes:

Main:

1. Savelyeva G.M. Obstetrics: Obstetrics: Textbook for honey. universities, 2007

Additional

Abramchenko, V.V. Active management of labor: A guide for doctors.-2nd ed., rev. /IN. V. Abramchenko. - SPb.: Special. lit., 2003.-664 p.

Obstetrics and gynecology: Textbook / Ch. Beckmann, F. Ling, B. Barzhanski et al. /Trans. from English - M.: Med. lit., 2004. - 548 p.

Aylamazyan, E.K. - Obstetrics: Textbook for medical professionals. universities / ed. text by E.K. Ailamazyan. - 5th ed., additional.. - St. Petersburg: Spets.lit., 2005. - 527 p. : silt, solid (Textbook for medical universities)

Duda V.I., Duda V.I., Drazhina O.G. Obstetrics: Textbook. - Minsk: Higher. school; Interpressservice LLC, 2002. - 463 p.

Zhilyaev, N.I. Obstetrics: Phantom course / N.I. Zhilyaev, N. Zhilyaev, V. Sopel. - Kyiv: Book Plus, 2002. - 236 p.

Teaching aids

Clinical lectures on obstetrics and gynecology: Tutorial/ed. A. I. Davydov and L. D. Belotserkovtseva; Ed. A. N. Strizhakov. - Moscow: Medicine, 2004. - 621 p.

Handbook of obstetrics, gynecology and perinatology: Textbook / Ed. G. M. Savelyeva. - Moscow: LLC "Medical Information Agency", 2006. - 720 p.

Guide to practical classes on obstetrics: Proc. allowance /Ed. V.E. Radzinsky. - M.: Med. information agency, 2004. - 576 p. -(Educational literature for students of medical universities)

Guide to practical training in obstetrics and perinatology/Ed. Yu. V. Tsvelev, V.G. Abashin. - St. Petersburg: Foliant, 2004. - 640 p.

Trifonova, E.V. Obstetrics and gynecology: Textbook. allowance /E.V. Trifonova. - M.: VLADOS-PRESS, 2005. - 175 p. - (Lecture notes for medical universities)

Tskhai, V.B. Perinatal obstetrics: Textbook. allowance /V.B. Tskhai. - M.: Med. book; Lower Novgorod: NGMA, 2003. - 414 p. - (Textbook for medical universities and postgraduate education)

Standards of answers to questions of practical knowledge and skills in obstetrics and gynecology: Textbook. manual/ V.B. Tskhai et al. - Krasnoyarsk: KaSS, 2003. - 100 p.

Biomechanism of childbirth- are the movements of the fetus in the aggregate that the fetus makes when moving along the birth canal of the mother. These movements can be roughly divided into flexion, extension and rotation; they are the ones that help the mother give birth to her baby.

When the fetal head reaches the narrow part of the mother's small pelvis and encounters an obstacle here, labor intensifies, which leads to increased and increased frequency of various movements in the fetus.

1) Biomechanism of labor in anterior occipital presentation

2) Biomechanism of labor in posterior occipital presentation

Today we will look at the biomechanism of childbirth in the anterior form of occipital presentation, which is more often observed in the first position.

Occipital presentation - in this condition, the fetal head is bent and its lowest part is occipital part heads. According to statistics, 93–96 percent of all births occur in this condition.

Biomechanism of labor in anterior occipital presentation

The first point is that the cervical spine begins to bend, and the fetal chin begins to approach chest, occipital region descends, while the fetal forehead stops above the entrance to the pelvis. In this case, the lowest point on the fetal head becomes a point on the sagittal suture, located closer to the small fontanel.

The second point is the internal rotation of the head

When the fetus continues its forward movements, it encounters difficulty in the pelvic cavity, this is due to the shape of the birth canal. The fetus begins a circular movement around its longitudinal axis, while the fetal head begins to turn as it exits the wide part of the small pelvis into the narrow part, the fetus continues to move along the lateral inner wall of the pelvis, heading towards the pubic symphysis. Anterior section the heads shift to the sacrum.

The third point is extension of the head

At the third stage, as the movement of the fetus continues in the birth canal, the fetus begins to unbend; usually, extension during childbirth occurs at the outlet of the pelvis (during physiological childbirth). The structure of the birth canal places the deviation of the fetal head towards the womb. The “suboccipital” fossa is pressed against the lower edge of the symphysis pubis, creating a point of fixation and providing support. The head continues to rotate around the fulcrum with its transverse axis and, within a few attempts, is fully unbent. After which the fetus is born through the vulvar ring, birth occurs from the back of the head to the chin.

The fourth point is the rotation of the shoulders (internal) and the rotation of the fetal head (external)

When the fetal head is practically unbent, the fetal shoulders rise to the transverse size of the inlet at the small pelvis, or to one of the oblique sizes. Along the path of the fetus, the shoulders move in a helical manner, simultaneously moving down and continuing the helical movements. The fetal shoulders change from the transverse dimension of the pelvic cavity to an oblique dimension, and the plane to a straight dimension; this rotation occurs when the fetal torso passes through the narrow part of the pelvic cavity and is transmitted to the fetal head. When transferring to the head, depending on whether it is the first or second position, the back of the head turns towards the mother’s left or right thigh.

Next, the anterior shoulder forms a second place of support - fixation between the deltoid muscle and the lower edge of the symphysis. When the action of birth forces occurs, the fetal torso begins to bend at the chest spinal region, after which the birth of the fetal belt occurs. The front shoulder is born first, followed by the birth of the second shoulder. Good preparedness of the birth canal after the birth of the fetal head allows the rest of the fetal body to be born easily.

Interestingly, the fetal head is anterior view of occipital presentation has a dolichocephalic shape due to the birth tumor and its configuration.