Can blood tests be wrong? Final diagnosis. When does an HIV test give a false result? Incorrect negative hCG test

December 1 is World AIDS Day. On the eve of this date, the Russian Ministry of Health cited frightening statistics according to which the number of cases will increase by 2.5 times in just 15 years. HIV prevention is now one of the main directions of modern medicine, aimed at stopping the spread of the virus. And, first of all, you need to start with tests. AiF.ru found out where you can get tested for HIV and how to do it correctly so as not to get a false result.

Two types of verification

There are two main types of tests for HIV/AIDS: enzyme immunoassay and PCR diagnostics. Both are informative and accurate.

Enzyme immunoassay is the most common today. It is based on the detection of antibodies to HIV in the patient’s blood serum. In most patients, they appear approximately 4-6 weeks after infection, in 10% - after 3-6 months, and in 5% - later. Therefore, ideally this test should be taken three times every 3 months.

PCR diagnostics are a polymerase chain reaction test that can test serum, antiviral RNA or DNA, and quantify CD-4 lymphocytes. At the same time, doctors often call PCR analysis the only possible early diagnosis of HIV infection, which is also carried out in children of the first year of life. The advantage of this research method is the fact that it can detect the virus in the incubation and early clinical periods, when there are no antibodies in the blood yet. This helps to start treatment earlier and reduce the negative impact of the disease.

How to prepare?

You need to prepare for an HIV/AIDS test. Blood should be donated on an empty stomach, and the last meal should take place no later than 8 hours before. Naturally, it is recommended to maintain a unique diet, a few days before donating blood, giving up alcohol and “harmful” foods - fatty, fried, smoked foods, marinades and other refined foods.

It is worth considering that if you are unwell, even with any viral or infectious disease, it is better not to donate blood or come back for testing again 35-40 days after recovery. Otherwise, there is a risk of getting a false positive result.

The HIV/AIDS test goes through several stages of testing. Therefore, it takes 2-10 days to prepare.

Negative plus

The result can be positive, negative or doubtful. In the latter case, it is worth retaking the analysis a little later.

Doctors say that if the result is positive, it is impossible to immediately declare that a person has HIV or AIDS. Indeed, in some cases, indicators may be overestimated for other reasons. In this situation, you should retake the test again - everyone who has a “+” result goes through this procedure.

Where does the “false signal” come from? Due to certain diseases and conditions that may cause cross-reactions. For example, due to allergies, antigens that are incomprehensible to the body can be produced in the blood, which it recognizes as foreign.

Also, a similar reaction can occur due to a sharp change in blood composition - for example, due to a jump in cholesterol (with excessive consumption of fatty foods, fried foods, seeds), hormonal imbalance (in particular, during menstruation in women), infections (respiratory diseases, the presence of hepatitis and influenza viruses, recent vaccinations, tuberculosis), excessive blood thickness, arthritis, oncology. Fungi, viruses and bacteria can also contribute to the appearance of incorrect data. In addition, a false positive result can occur due to medical errors: violation of the rules for collecting and transporting blood, use of low-quality serum, and improper storage of the material.

Degrees of anonymity

If you wish, you can get tested for the immunodeficiency virus at any time. However, there are a number of situations when it is recommended to do this. Thus, it is worth donating blood when planning a pregnancy, before a planned operation, after questionable injections, unprotected sexual contact with a stranger, or in case of a sharp deterioration in health.

You can get checked at any clinic, private clinics and diagnostic centers, as well as specialized AIDS centers. Moreover, in public medical institutions this procedure will be completely free. Any citizen of the country can take tests at the AIDS center, regardless of where he lives.

There are two types of testing: confidential and anonymous. In the first case, the person tells the laboratory assistants his name. In the second case, he is assigned an identification number. All results are given exclusively to the patient, and even if the result is positive, the laboratory cannot report it anywhere - this will be regarded as a violation of medical confidentiality. In paid clinics, the principle of taking tests is no different, only in this case the service is provided for money. The cost is from 400 to 3,400 rubles, depending on the complexity and verification options.

External manifestations that appear in the later stages can be easily confused with other diseases. Therefore, a lot depends on the results of laboratory tests. But this branch of medicine cannot yet offer a universal analysis for verifying syphilis.

Tests for syphilis: diagnostic approaches

All methods that are used to detect syphilis fall into two different categories.

The key difference between them is the following:

• Search directly for the pathogen. These are so-called direct tests. The material is a fragment of tissue obtained from a suspicious lesion.
• A study to identify specific antibodies - immunoglobulins - that the immune system produces in response to the entry of Treponema pallidum into the blood. The material for research is blood plasma.

Both of these categories have their own advantages and disadvantages. In the first case, it is important that the spirochete cells get into the test sample (high specificity, but not always acceptable sensitivity).

Methods from the second category, on the contrary, have high sensitivity, but their specificity leaves much to be desired. So the truthful answer to the question is, can a syphilis test be wrong?, unequivocal: yes. And in both directions - or false negative. Especially if the study was carried out using only one method.

Testing for syphilis: direct tests

These include tests for syphilis, which detect either the treponema itself or its unique genetic material.

For this purpose, the following are used in medical practice:

• Studying a sample under a microscope in a dark field - dark-field microscopy.
• Direct immunofluorescence. This is a modification of dark-field microscopy.
• Search for Treponema DNA fragments using polymerase chain reaction (PCR).

For dark-field microscopy, discharge is taken from an accessible suspicious lesion. If the result is positive, living, motile spirochetes are visible in the eyepiece. Direct fluorescence uses the same material as dark-field microscopy. The sample is fixed with paraffin. And anti-treponemal antibodies, pre-labeled with a fluorescent dye, are applied to it. If the material contains the causative agent of syphilis, immunoglobulins bind tightly to proteins on the surface of the microbe and glow in ultraviolet light. It is quite easy to notice such a glow.

These tests are cheap and have high specificity but low sensitivity.

For a reliable result, it is necessary that the sample contains at least 1000 - 100,000 microbial bodies. And for dark-field microscopy it is important that they are alive and moving. The PCR method allows you to give an accurate result if the test sample contains at least 10 spirochetes. Specificity reaches 100%, so doubt Can a syphilis test be false positive? in this case, it shouldn’t.

However, if you do not follow the sampling technique or make a technical error during the study, you can get a false negative result. And this is a significant drawback. The cost of the study is also quite high.

Can a hepatitis C test be wrong? Unfortunately, such cases sometimes happen. This pathology is dangerous because after infection, a person often has no symptoms for many years. Accuracy in diagnosing hepatitis C is especially important, since if not detected and treated in a timely manner, the disease leads to catastrophic complications: cirrhosis or liver cancer.

Types of diagnostics

Hepatitis C viruses are transmitted through blood, so blood testing is important. The immune system produces protein antibodies against pathogens - immunoglobulins M and G. They are markers by which liver infection is diagnosed using an enzyme-linked immunosorbent assay (ELISA).

About a month after infection or during an exacerbation of chronic hepatitis C, class M antibodies are formed. The presence of such immunoglobulins proves that the body is affected by viruses and quickly destroys them. As the patient recovers, the number of these proteins steadily decreases.

Antibodies G (anti-HCV IgG) are formed much later, in the period from 3 months to six months after the invasion of viruses. Their detection in the bloodstream signals that the infection occurred a long time ago, so the severity of the disease has passed. If there are few such antibodies and in a repeated analysis they become even smaller, this indicates the patient’s recovery. But in patients with chronic hepatitis C, immunoglobulins G are always present in the circulatory system.

Laboratory tests also determine the presence of antibodies to the non-structural viral proteins NS3, NS4 and NS5. Anti-NS3 and Anti-NS5 are detected early in the disease. The higher their indicator, the more likely it is to become chronic. Anti-NS4 helps determine how long the body has been infected and how severely the liver is affected.

A healthy person does not have blood tests. Each of these liver enzymes indicates an early stage of acute hepatitis. If both are detected, this may signal the onset of liver cell necrosis. And the presence of the enzyme GGT (gamma-glutamyl transpeptidase) is one of the signs of organ cirrhosis. Evidence of the destructive work of viruses is the presence of bilirubin, the enzyme alkaline phosphatase, and protein fractions in the blood.

The most accurate diagnosis, if carried out correctly, is the PCR (polymerase chain reaction) method. It is based on identifying not immune antibodies, but the structure of RNA (ribonucleic acid) and the genotype of the hepatitis C pathogen. Two variants of this method are used:

• qualitative - there is a virus or not;
• quantitative - what is its concentration in the blood ().

Decoding the results

“The test for hepatitis C is negative.” This formulation confirms the absence of the disease in a qualitative PCR study. A similar result from a quantitative ELISA test shows that there are no virus antigens in the blood. In immunological studies, their concentration is sometimes indicated below normal - this is also a negative result. But if there are no antigens, but there are antibodies to them, this conclusion signals that the patient has either already had hepatitis C or has recently been vaccinated.

“The test for hepatitis C is positive.” This formulation requires clarification. The laboratory can give a positive result to a person who was once acutely ill with it. The same wording applies to people who are currently healthy but are virus carriers. Finally, it may be a false test.

In any case, the study must be repeated. For a patient with acute hepatitis C who is being treated, the doctor may order testing every 3 days to monitor the effectiveness of therapy and the dynamics of the condition. A patient with a chronic illness must undergo follow-up tests every six months.

If the antibody test result is positive and the PCR test result is negative, the person is considered potentially infected. To verify the presence or absence of antibodies, diagnostics are carried out using the RIBA method (RIBA - recombinant immunoblot). This method is informative 3–4 weeks after infection.

Options for false tests

In medical practice, there are 3 options for inadequate diagnostic test results:

• doubtful;
• false positive;
• false negative.

The enzyme immunoassay method is considered very accurate, but sometimes it gives erroneous information. A questionable analysis is when the patient has clinical symptoms of hepatitis C, but there are no markers in the blood. Most often this happens when the diagnosis is too early, since antibodies do not have time to form. In this case, a repeat analysis is done after 1 month, and a control analysis after six months.

The doctor receives it when class M immunoglobulins are detected by ELISA, but viral RNA is not detected by PCR. Such results often occur in pregnant women, patients with other types of infection, and cancer patients. They also need to do repeated tests.

False-negative results appear very rarely, for example, during the incubation period of the disease, when a person is already infected with the hepatitis C virus, but there is still no immunity to it and no symptoms. These results may occur in patients who take drugs that suppress the body's defense system.

What else is determined during diagnosis?

Hepatitis C progresses differently depending on the genotype of the virus. Therefore, during diagnosis, it is important to determine which of its 11 variants is in the patient’s blood. Each genotype has several varieties, which are assigned letter designations, for example 1a, 2b, etc. You can accurately select the dosage of drugs and the duration of treatment by finding out the type of virus.

In Russia, genotypes 1, 2 and 3 are predominantly common. Of these, genotype 1 is the worst and takes the longest to treat, especially subtype 1c. Options 2 and 3 have more favorable prognoses. But genotype 3 can lead to a serious complication: steatosis (fatty liver). It happens that a patient is infected with viruses of several genotypes at once. Moreover, one of them always dominates over the others.

Diagnosis of hepatitis C is indicated if:

Causes of erroneous analyzes

False-positive tests, when there is no infection in the body, but the results indicate its presence, account for up to 15% of laboratory tests.

Causes of errors:

False positive test results are possible if the expectant mother:

• metabolism is disrupted;
• there are endocrine, autoimmune diseases, flu and even a common cold;
• specific pregnancy proteins appear;
• The level of microelements in the bloodstream decreases sharply.

In addition, errors in hepatitis C tests may be due to human error. Often affects:

• low qualification of laboratory technician;
• erroneous analysis of someone else's blood;
• low-quality chemical reagents;
• outdated medical devices;
• contamination of blood samples;
• violation of the rules for their transportation and storage.

Any laboratory can sometimes make mistakes. But this is possible with only ELISA or only PCR tests. Therefore, when diagnosing the disease, both research methods should be used. Then it is most reliable, since it is difficult to make a mistake if there is no virus in the blood.

It is important to get tested for hepatitis C when there are no ailments, even a mild cold. There is no need to donate blood on an empty stomach. You should just give up fatty, fried, spicy foods and not drink alcohol the day before. One last thing: an initial false positive result for hepatitis C is not a reason to panic. A conclusion should be made only after additional research.

Many women are interested in whether the hCG test can be erroneous. Human chorionic gonadotropin usually appears in the urine during pregnancy. This hormone is produced when a fertilized egg attaches to the uterine walls. This test detects pregnancy within a few days.

The strip test is also based on the amount of gonadotropin, but it often turns out to be defective. Therefore, it is better to donate blood for hCG, since this test is more reliable and gives correct results in 99% of cases. In some cases, the examination may give a false positive or false negative result. Therefore, it is better to understand whether a blood test for hCG can be wrong.

Causes of a false negative result

This analysis is highly accurate. At the same time, the human factor cannot be excluded, since the person conducting the research may make a mistake. However, situations where laboratory assistants made a mistake are rare. Doctors often interpret a positive test result as evidence of pregnancy, which is not entirely correct. For an accurate result, it is better to donate blood several times (about once a week). In a pregnant woman, the amount of hCG will increase 2-3 times with each analysis. If the concentration of human chorionic gonadotropin remains at the same level, this may indicate an ectopic or frozen pregnancy.

Human chorionic gonadotropin is found in the blood of all people. However, in pregnant women the level of this hormone is 2-3 times higher than in non-pregnant women.

An incorrect test result with a low hormone content may occur in the following cases:

1. Pregnancy is too short. Blood tests for hormones have a certain degree of sensitivity to gonadotropin. Typically, the required concentration of the hormone appears only by the 5th day of a missed period. Before this period, most tests will not show pregnancy. There are some studies that determine the presence of a fertilized egg in the uterus already on the 10th day after conception. They can be performed on 1 day of missed menstruation. But before this period, pregnancy cannot be detected, since the amount of hCG in the blood is too low.
2. Pathological course of fetal development. If the pregnancy is ectopic, or there is a threat of miscarriage, then a very small amount of the hormone is produced and it cannot be detected.
3. Placental insufficiency or weak implantation of the fetus to the uterine wall. In these cases, the body produces very little human chorionic gonadotropin, so the analysis is not able to detect pregnancy, despite its presence. The same result is possible with late attachment of the embryo to the walls of the uterus.

Reasons for a false positive result

The hCG test can also be erroneous in cases where too much human chorionic gonadotropin is formed in the body of a non-pregnant woman. This is a serious hormonal disorder. Then a blood pregnancy test may give false positive results.

A woman’s body can produce an increased amount of human chorionic gonadotropin in diseases of the pituitary gland, as well as in tumors of other organs.

High levels of this hormone can be observed with pituitary adenoma. Typically these tumors are hormonally active. Those who have adenomas often suffer from endocrine disorders, which lead to an increase in gonadotropin. In this case, the hormone is produced not by chorion tissue (embryonic membranes), but by pituitary cells.

False test results and elevated levels of human chorionic gonadotropin, not associated with pregnancy, can be observed with malignant tumors. An hCG test is often a tumor marker. An increase in gonadotropin may indicate the following diseases:

• mammary cancer;
• lungs' cancer;
• ovarian cancer;
• stomach and liver cancer.

In addition, an increase in the hormone can indicate tumors such as chorionic carcinoma and hydatidiform mole. Chorionic carcinoma is a tumor of the uterus that forms after a previous pregnancy. In this case, chorionic villi remain in the uterus, which then degenerate into a malignant formation. Chorion particles can continue to produce hormones.

Hydatidiform mole is a pathology of pregnancy that begins in the early stages. Due to incomplete fertilization of the egg, tissue in the form of bubbles grows in the uterus instead of the placenta. The embryo dies, but the pathological formation grows and continues to produce the hormone.

This suggests that an increase in human chorionic gonadotropin not associated with pregnancy may indicate serious pathologies that require urgent treatment.

Of course, a false positive test result does not always indicate tumors and other dangerous diseases. Most often, an increase in human chorionic gonadotropin is associated with hormonal imbalance. In middle-aged women, this hormone increases during the period before menopause.

A false test result may occur in a woman who has recently undergone an artificial termination of pregnancy. In this case, the hormonal levels have not yet returned to normal.

The test result is incorrectly defined as positive when ingesting or injecting drugs containing human chorionic gonadotropin. These drugs include:

• Profasi;
• Decayed;
• Human gonadotropin;
• Human chorionic gonadotropin;
• Choriogonin;
• Horagon;
• Ovitrel.

These drugs are quite often used in the treatment of infertility and before the IVF procedure, so the likelihood of an error due to taking the medication is quite high. If the patient has undergone a course of therapy with such drugs, the laboratory assistant must be informed about this. Other medications, including hormonal contraceptives, usually do not distort the results of a pregnancy test.

What to do if the analysis result is false

You should know what to do if the blood test result gives positive or negative results that are in doubt.

You can retest. In this case, it is necessary to avoid taking drugs with choriogonin. Usually a repeat test is done after a few weeks.

Additional research can also be done. For example, take a urine test for human chorionic gonadotropin. You can use a two strip test. Ultrasound can help confirm or refute pregnancy. It shows gestation at 5-7 obstetric weeks.

If pregnancy is not confirmed by any other tests, but human chorionic gonadotropin in the blood continues to remain high, the patient must undergo a comprehensive examination. You should contact an endocrinologist, gynecologist, mammologist and oncologist. You need to undergo a series of tests that will reveal the function of the pituitary gland and ovaries. In addition, the doctor may prescribe a pelvic ultrasound and mammography.

A high level of gonadotropin production in a non-pregnant woman may be the result of a temporary hormonal imbalance. But sometimes this can indicate serious illnesses that require treatment. In addition, a large amount of this hormone does not leave its mark on the body. Elevated levels of hCG lead to the appearance of luteal cystic formations in the ovaries. Most often they disappear on their own. But in some cases, cysts can grow to large sizes, which threatens their rupture and acute pain.

In contact with

Planning a pregnancy is a special period in a woman’s life, which does not always proceed joyfully and smoothly. Sometimes the two treasured stripes do not appear for a long time. Life turns into endless waiting.

The most patient wait for a delay in menstruation, and then another week later they conduct a regular test that reacts to the level of hCG in the urine. Those who can’t stand it do an analysis for the hCG content in the blood serum. It contains a higher concentration of the hormone.

An analysis for hCG in the blood makes it possible to diagnose pregnancy 7-10 days after the embryo attaches to the uterus. The method is considered highly accurate, its reliability is 99-100%. Can hCG not show pregnancy in the early stages, be false negative or false positive? Yes, sometimes this is possible. Read on to learn about the reasons for the erroneous result.

When are errors possible in hCG analysis?

To answer the question in more detail whether the hCG analysis can be erroneous, you should start from the specific situation. The level of human chorionic gonadotropin in the blood can change under the influence of drugs, due to the development of tumors, for physiological reasons. An error by the laboratory itself, poor-quality sampling of material, confusion with results, or problems with reagents cannot be ruled out.

It's important to understand that hCG analysis is as informative as possible during a comprehensive examination. You cannot draw a conclusion based on the concentration of the hormone in the blood alone.

What is hCG?

HCG is an acronym that stands for human chorionic gonadotropin. It is a hormone primarily used to diagnose pregnancy. HCG begins to be produced by the chorion (the embryonic part of the placenta) 6-8 days after fertilization of the egg. With normal fetal development, in just 7-11 weeks the level of the hormone increases to thousands of values.

What is human chorionic gonadotropin used for?

• helps a woman’s body adapt to pregnancy. Thanks to the secretion of glucocorticoids, as well as physiological immunosuppression, the development of a semi-foreign genetic organism within the uterus becomes possible;
• maintains the functional activity of the corpus luteum until the placenta matures (10-12 weeks). Thanks to hCG, the body produces a sufficient amount of the hormone progesterone, which plays a vital role in maintaining pregnancy;
• supports the development and functioning of the placenta, improves trophism and promotes the quantitative growth of chorionic villi (chorionic cells that grow into the uterine mucosa and participate in the formation of the placenta);
• taking hCG drugs is used to solve the problem of infertility in women, to prevent miscarriage in the first trimester. In the male body, the hormone stimulates the production of sex hormones and spermatogenesis.

HCG is not produced in the body of healthy men and non-pregnant women. Otherwise, an increase in hormone levels may indicate the development of a malignant tumor.

Why do you need to get tested for hCG?

Measuring the level of hCG in the body allows you to establish pregnancy and identify abnormalities in its development. Less commonly, it is used to exclude malignant processes (oncological diseases).

The most affordable way to measure hCG is to take a regular pharmacy pregnancy test. They come in several types (strips, inkjet, electronic), and react only to the hormone content in the urine. At the required concentration of hCG, the second strip turns red. The urine reacts with a special chemical that is used in the test. They have different sensitivity, on average, they respond to a hCG concentration of 20–25 mIU/ml and give accurate results starting from the eighth day of missed menstruation.

A blood test for the content of human chorionic gonadotropin allows not only to determine pregnancy in the early stages, but also to determine the exact amount of the hormone. The analysis is more informative and reliable. The volume of hCG required for diagnosis in the blood serum appears earlier than in the urine. Already on the first day of implantation, the hCG level can reach 2-10 mU/ml; within 7 days the value increases to 22-105 mU/ml.

Rules for taking the analysis

Laboratory testing to determine early pregnancy is recommended after a 3-5 day delay in menstruation. Otherwise, the result may be false negative. HCG levels increase differently in women. In addition, it is not always known when implantation occurred. With late ovulation, the result on the first day of the delay may be questionable. Very often the analysis is done not once, but several times to observe dynamics.

What rules apply when conducting a laboratory test:

• You need to take the test in the morning on an empty stomach. If a different time is chosen, food intake stops 4-6 hours before;
• the doctor must be notified about taking medications;
• to establish the fact of pregnancy, hCG analysis is carried out in combination with an ultrasound intravaginal sensor;
• if a questionable result is obtained, the analysis is repeated after 2-3 days;
• To diagnose fetal pathologies, a study of hCG levels is carried out at 14-18 weeks of pregnancy.

A gynecologist usually talks about the rules for preparing for an hCG analysis. The doctor may make individual recommendations, such as stopping certain medications or other recommendations, based on the patient's medical history (the totality of information obtained during a medical examination).

Norms of hCG in the blood of pregnant women

Material for research is collected from a vein. The level of hCG during early pregnancy increases daily until 7-11 weeks. Then the concentration of the hormone in the blood gradually decreases. The standards that doctors are guided by are given in the table:

In men and non-pregnant women, hCG levels are 0-5 mU/ml.

It should be taken into account that laboratories use different reagents and therefore the standards may differ from the statistical average. You should rely on the values ​​indicated on the sheet with the analysis result. Usually the normal limits are indicated in the extreme column on the right or below.

Standards for implantation days

Due to the fact that the obstetric gestational age (based on the date of the last menstruation) often differs from the actual one, it is more correct to focus on another table. However, it only works if the woman knows exactly on what day the fertilized egg was implanted into the uterine wall. Many feel this moment quite clearly - a pain appears in the lower abdomen, and a few drops of blood are found in the vaginal discharge.

When making calculations, it should be taken into account that the day of implantation does not coincide with ovulation. After fertilization, the egg migrates into the uterine cavity and attaches to it approximately on days 3–12 (usually 8–10).

Norms for in vitro fertilization (IVF)

HCG levels after IVF double every 36-72 hours. To determine the norm, both standard tables and special ones are used, taking into account the age of the embryo and the day of its transfer.

The first test for hCG levels is carried out on the 14th day after IVF. A value of 100 mU/ml is regarded as pregnancy. A reading below 25 mU/ml indicates that conception has not occurred.

Deviations hCG from normal

If the concentration of hCG does not correspond to the values ​​​​in the table, the woman is prescribed additional examinations and tests. There are deviations from the norm, both smaller and larger. A negative hCG, as well as a reading of 0-5 mU/ml, excludes pregnancy.

Low hormone levels may mean:

• the gestational age is calculated incorrectly;
• fetal development has stopped, frozen pregnancy;
• ectopic pregnancy;
• risk of miscarriage;
• chronic placental insufficiency;
• changes in hormonal levels and the rate of hCG synthesis;
• death of one fetus when carrying twins;
• post-term pregnancy.

Too high a hCG level may be a sign of:

• multiple pregnancy;
• toxicosis;
• gestational diabetes mellitus;
• tumors in a pregnant woman;
• developmental defects of the baby;
• chromosomal abnormalities in the fetus;
• taking gestagens.

Can a blood test for hCG be wrong? This rarely happens. The accuracy of the laboratory test is 99-100%. But we must not forget about the human factor. Laboratories employ people who can simply confuse the collected material. If the prognosis is unfavorable, it is better to retake the test again.

False positive result

This includes the situation when there is no pregnancy, and the hormone level exceeds 5 mU/ml. Reasons why the test is positive:

• HCG can be produced in the body during hydatidiform mole, when after conception the embryo does not develop normally, and the chorionic villi grow in the form of bubbles (from 1 case in 100 pregnancies to 1 in 5000). In 15-20% of cases it transforms into a malignant tumor;
• taking human chorionic gonadotropin drugs. Used to treat infertility, restore the menstrual cycle;
• postmenopause. For physiological reasons, the level of hCG after menopause can reach 14 - 15 IU/l. There are often cases when, when passing a pharmacy test (sensitivity 10 IU/l), women appear 2 stripes, although there is no pregnancy and cannot be;
• diseases: ulceration of the stomach and duodenum, inflammation of the gastrointestinal tract, some liver diseases, tumors of internal organs, cancer of the lungs, stomach or pancreas. At a level of 1000 mU/ml, the prognosis for the patient is positive;

Other reasons for increased hCG besides pregnancy:

• biochemical pregnancy;
• recent abortion;
• miscarriage.

Sometimes a sperm successfully fertilizes an egg and the fertilized egg even manages to attach to the walls of the uterus, but the time for menstruation comes and the pregnancy is terminated. In this case, a woman may not feel its signs, not pay attention to heavier menstrual flow, or a slight delay. It turns out that there is no longer pregnancy, but the hCG level is increased. After an abortion or miscarriage, the concentration of the hormone decreases within 4-6 weeks.

Also, the possibility of pregnancy cannot be completely ruled out. A laboratory hCG test can show an interesting situation at the earliest stages, when neither test strips nor some ultrasound machines can confirm it.

False negative result

Can hCG be negative during pregnancy? Yes maybe. This is especially often observed when using test strips and early diagnosis even before the delay (90% of cases). Possible reasons for a false result:

• analysis carried out too early;
• late ovulation on days 18-26 of the menstrual cycle;
• late implantation of the embryo on days 11-12 from conception;
• individual characteristics of the rate of hCG production;
• conducting a home pregnancy test when drinking a lot (the concentration of the hormone in the urine decreases), a defective test.

If the hCG is negative before the delay or a few days after it, there is no need to worry. The best solution is to observe the hormone concentration over time. If conception has occurred, then after a few days the indicators will increase several times.

List of drugs that can affect hCG levels

Can the hCG test be erroneous when taking medications? Yes maybe. List of drugs that increase the concentration of the hormone in the blood (containing human chorionic gonadotropin):

• Decayed;
• Horagon;
• Gonakor;
• Profasi;
• Chorionic gonadotropin.

List of drugs that reduce the concentration of the hormone in the urine (diuretics):

• Diacarb;
• Furosemide;
• Veroshpiron;
• others, including herbal preparations.

As for taking gestagens ( Duphaston, Progesterone, Utrozhestan), doctors have not identified a direct effect on human chorionic gonadotropin. These drugs cannot cause false hCG levels during early pregnancy. Also, diet, unbalanced nutrition, smoking, and alcohol do not affect the hormone content.

How long can a test not show pregnancy?

Many women force things and rush to check hCG even before the delay. But the result often does not bring peace of mind, but makes you worry even more. In order not to worry about a possible error in the end, you should adhere to the deadlines specified by doctors and conduct testing 3-5 days after the delay. In case of irregular menstruation, it is recommended to take the test 12-15 days after ovulation.

So, can the hCG blood test be wrong? The reliability of a laboratory test depends on many factors, ranging from the correct preparation of the woman for collecting the material, ending with the potential of the chosen laboratory, the level of qualifications of the laboratory assistant and doctor. In addition, the patient’s medical history is important: whether she is taking medications, whether she had a recent miscarriage, when ovulation occurred, and much more. You should contact your doctor and correctly interpret the test result, repeat it if necessary, and undergo additional tests.