Screening 2 trimester blood decoding. Second screening during pregnancy: timing and what it shows

The second screening for pregnant women is a comprehensive diagnosis necessary to identify possible pathologies and abnormalities in the development of the embryo. The procedure also helps confirm the results of the 1st screening. In this article we will talk about the timing, features of the preparation and the results obtained.

Screening translated from in English means "sifting", that is, the identification of women who are in " interesting position who are at risk. After completing this examination, if necessary, a woman can be sent for additional tests confirming or refuting the results of screening diagnostics.

The screening procedure is performed at specific stages of pregnancy. It includes:

1. Conducting an ultrasound examination performed on an expert-class apparatus is not by an ordinary doctor, but by a professional who is specifically involved in identifying any fetal malformations.
2. Testing to determine the amount of different hormones. At the 1st screening, as a rule, 2 hormones are determined, and in the case of the 2nd screening, the doctor must decide this issue based on each specific case.

When is the 2nd screening performed?

This diagnosis can be carried out for a period from 16 to 20 weeks of pregnancy. This time period is extremely important, especially for biochemical blood tests, since hormone levels do not remain stable, but constantly change. First, ultrasound diagnostics are performed, and then they are sent for blood donation.

Please note that many doctors believe that the most accurate results of the 2nd pregnancy screening can be obtained at 17 weeks.

The indications for the procedure remain the same as in the 1st trimester. It is mandatory to conduct this examination in the following cases:

• if the future parents are relatives;
• a woman suffered an acute bacterial or viral pathology while pregnant;
• the expectant mother has a genetic disease that can be transmitted to the baby;
• one or both future parents suffer from a genetic (chromosomal) pathology;
• earlier, a woman had miscarriages, childbirth took place before the due date;
• the family already has a child with developmental anomalies;
• one or more of the woman's pregnancies ended in the death of the fetus;

In addition, doctors will definitely refer you for the 2nd screening if:

• the first ultrasound examination (performed at 14 weeks and later) revealed the presence of any developmental disorders of the embryo (if this happened more than early dates, the woman will be sent for 1st trimester screening);
• in the time interval from 14 to 20 weeks, the woman suffered an acute infectious pathology;
• a formation of various etiologies was detected later than at the fourteenth week.

In the last two situations, a pregnant woman will need to get advice from a geneticist, who will conclude how important full screening is in this situation. In some cases, doctors are limited to only repeated ultrasound diagnostics without a blood test.

What will this survey show?

Let us consider in more detail what exactly the specialist will determine during the second screening.

On ultrasound examination:

• the length of the body of the fetus is determined, as well as the length of the bones;
• head circumferences, chest and belly;
• measure the nasolabial triangle;
• it is possible to assess how symmetrically the facial structures develop;
• the state of the structures of the skull and spine is determined;
• diagnose the condition internal organs fetus and maternal organs.

On biochemical screening, it is proposed to evaluate the performance of three or four hormones. So, the level of content in the blood of a pregnant woman of chorionic gonadotropin, inhibin A, unconjugated form of estriol and alpha-fetoprotein is detected. So, what should be the indicators of these hormones in the normal state:

1	Chorionic gonadotropin	Its normal amount in the blood at this time varies from 10 to 35 thousand mU / ml. At the same time, it is important not only to identify its amount, but also to compare its ratio with the amount of other studied hormones, namely, estriol and alpha-fetoprotein. It will also help identify possible pathologies.
2	Alpha fetoprotein	Most of this hormone is produced in the fetal liver. Alpha-fetoprotein has protective properties for the fetus, prevents the immune system of the pregnant woman from accepting the fetus as a foreign body
3	Estriol	The initial production of this hormone occurs in the placenta, and then estriol begins to be produced in the fetal liver with the participation of the adrenal glands. Estriol is important for preparing the uterus and mammary glands for the birth of a baby and the subsequent breastfeeding. The amount of the hormone gradually increases throughout pregnancy.
4	Inhibin A	This substance is necessary in order to prevent the maturation of new eggs during pregnancy. The indicator of the hormone under normal conditions should gradually decrease. Indicates Down's pathology increased amount inhibin A in the blood of a pregnant woman

So, for example, in the presence of Edwards syndrome, hCG levels are significantly lower than normal, and the level of fetoprotein also remains low. In case of abnormal development nervous system, chorionic gonadotropin will be normal with an increased level of fetoprotein.

With a reduced amount of the hormone Alpha-fetoprotein, we can talk about the prerequisites for the development of Down syndrome, Edwards syndrome or intrauterine fetal death. An increased amount of alpha-fetoprotein indicates possible disorders in the development of the neural tube, as well as some pathologies of the gastrointestinal tract. The hormone should be assessed in conjunction with other data.

A significant increase in estriol may indicate multiple pregnancy or large fruit. The concentration of estriol may decrease due to various chromosomal pathologies.

Of course, the data obtained from a biochemical blood test are only an assumption of the presence of a particular disorder. There is no need to panic ahead of time or tune in to the bad, because for sure only a born child can be diagnosed, and everything else remains just a guess.

Features of preparation

As mentioned earlier, the 2nd screening includes two examinations: ultrasound diagnostics and a blood test for hormones.

There is no need for any special preparation for ultrasound examination. At this time, the intestines move back due to the pressure of the enlarged uterus, and bladder, which previously served as a window for ultrasound, is now replaced by amniotic fluid.

Unlike the first trimester, when ultrasound could be performed in two ways: by inserting a probe into the vagina or by applying it to the skin of the abdomen, only the last diagnostic option remains available in the second trimester.

Preparation is necessary for biochemical research. The day before donating blood, you should completely exclude the consumption of the following products:

• chocolate (this includes all cocoa products);
• citrus;
• seafood;
• overly fatty and fried foods.

On the day of the study, you need to refuse to eat at all for 4-6 hours. It is only allowed to drink ordinary water, which does not contain gas, but even then no more than 150 milliliters.

Video - second trimester screening

results

Some women face such an unpleasant situation that the 2nd screening shows poor results. Of course, this is very unpleasant and exciting, but still try not to panic. The results of the study indicate only a high probability of the appearance of various pathologies, but are by no means a 100% guarantee of this.

Be that as it may, if at least one deviation from the norm was established at the second screening, the pregnant woman will be sent for additional research without fail.

In addition, the test results may not be normal due to the influence of certain factors:

• if the woman is pregnant naturally, but thanks to in vitro fertilization;
• in the presence of excess weight in a pregnant woman;
• if there are various chronic pathologies (for example, diabetes mellitus and others);
• if the expectant mother does not give up addictions and continues to smoke, drink alcohol, and so on.

It can be added here that in the case of multiple pregnancy, it makes no sense to conduct a biochemical blood test. Absolutely all indicators will be increased during the analysis, and doctors will not be able to calculate the risk of possible pathologies and developmental disorders. Ultrasound diagnosis is carried out as usual.

Thanks to the second pregnancy screening, the woman and her doctor have the opportunity to receive information about the condition of the fetus, its development, as well as the course of pregnancy. It is mandatory to conduct a screening study in the first and second trimesters, and in the 3rd trimester this procedure is resorted to only if there are special indications.

Do not be afraid of this study - it will not cause any harm to either your health or the health of the little man.

Tip: Perform all screenings in the same laboratory, this will greatly simplify the process of deciphering the results for the doctor.

D to eat or not?

There is, of course, no single answer to this question. On the one hand, it is much better to identify serious anomalies in development when the embryo is in its early stages and there is a possibility of abortion. On the other hand, today the methodology is not sufficiently informative to make such a serious decision.

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It is simply impossible to determine how the fetus grows and develops without performing a series of studies. very important medical method such diagnosis is the screening of the 2nd trimester of pregnancy.

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What it is?

Doctors call screening a whole range of examinations, which is necessary in order to identify various developmental anomalies in the fetus, as well as to determine how well it develops in the mother's womb. Pregnancy is a unique period in the life of every woman. At this time, the hormonal background changes significantly. This leads to the fact that the basal level of hormones changes. Also, specific biochemical markers may appear in the blood, which indicate the possible development of genetic and chromosomal pathologies.

In each of the periods of bearing a baby, pathologies manifest themselves in different ways. They can only be determined by laboratory diagnostics and ultrasound. Such studies are prescribed by an obstetrician-gynecologist. The expectant mother learns about screening, usually at the very first visits to the women's clinic. Screening during pregnancy is a recommended procedure. Not all women decide to go through it.

Quite often, only expectant mothers with any concomitant diseases of the internal organs undergo prenatal screening.

The introduction of prenatal screening in our country is relatively recent. A frightening demographic situation led to the development of such recommendations by doctors. Doctors note that the introduction of prenatal screening has significantly reduced maternal mortality. Thanks to this diagnostic complex, doctors began to identify dangerous genetic anomalies at the earliest stages of their formation.

The second trimester is the period when the embryo has moved on to the next stage of its development. At this time, the future baby of the doctor is already being determined as a fetus. The child continues to undergo differentiation of all vital systems of the body. This time is no less important than the first trimester of pregnancy. A full-fledged second screening includes a set of general clinical and biochemical tests, hormonal studies, and is also supplemented by mandatory ultrasound. In some cases, doctors may slightly expand the list of necessary tests.

Quite often this happens in a situation where some deviations from the norm were found in the future mother during the screening of the 1st trimester of pregnancy.

Many mothers believe that screening can prevent the development of congenital genetic diseases in their babies. It should be noted right away that, unfortunately, this is not the case. It is possible to prevent the appearance of chromosomal pathologies in a baby at the stage of preparation for pregnancy..

If conception has already occurred, then it is no longer possible to influence the formation of a specific genetic disease. However, it is quite often possible to identify certain pathologies with the help of screening. Such dangerous diseases as Down's disease, Edward's syndrome, Patau's syndrome and many other diseases can be determined using a specific diagnostic complex, which is carried out in the 2nd trimester of pregnancy. Screening also allows you to identify various malformations and anomalies in the structure of tubular bones.

Quite often, these tests also reveal congenital metabolic diseases, such dangerous pathologies include galactosemia, phenylketonuria, cystic fibrosis, and many others.

Dates

Doctors have established several decreed periods of pregnancy, in which it is most rational to do screening. In each of the trimesters of bearing a baby, there is one such diagnostic complex. Terms of passage are determined for all women. There are also certain clinical situations where they may be slightly shifted.

In this case, the specific dates for screening are determined by the obstetrician-gynecologist observing the patient.

In most situations, a set of studies is carried out at 16-20 weeks of pregnancy. As an exception, screening can be carried out after 21 weeks. Usually this situation occurs when a pregnant woman has any neoplasms in the ovaries. With these pathologies, the hormonal background changes significantly. To obtain more accurate results of biochemical analyzes, screening is postponed for 1-2 weeks.

Many mothers believe that ultrasound should be done on the same day as going to the laboratory. Doing this is completely optional.

Even a few weeks can pass between blood tests and ultrasound examination, this situation is quite normal.

Who should be screened?

Obstetrician-gynecologists recommend that all women who are carrying babies undergo such a complex, however, there are certain groups that simply need to be screened. Women who have indications for the study should not skip the prenatal diagnosis complex. This can lead to the fact that doctors simply do not find out in a timely manner about the presence of dangerous pathological conditions in the expectant mother and her baby. Doctors identify several decreed categories of women who simply need to be screened.

These groups include the following:

• Future mothers who conceived a baby after 35 years;
• Pregnant women with congenital malformations or a burdened family history of genetic or chromosomal diseases;
• Future mothers who have abnormalities in tests or ultrasound during 1 pregnancy screening;
• Pregnant women suffering from severe diseases of internal organs;
• Expectant mothers who have a burdened course of the 1st trimester of pregnancy with frequent threats of spontaneous miscarriage;
• Pregnant women who are forced to take immunosuppressive or hormonal medications for medical reasons while carrying a baby.

If the expectant mother during the 1st screening or later on ultrasound, doctors detect dangerous pathologies of fetal development, then in this case she is sent for additional diagnostics to the perinatal center. There, more experienced doctors perform expert-level ultrasound examinations.

In some situations, pregnant women with certain medical conditions are screened only in such perinatal centres.

Preparation

To obtain reliable and accurate results, it is very important for a future mother to prepare properly. A few days before the delivery of biochemical tests, she should definitely follow a lipid-lowering diet. It implies a restriction in the daily diet of all fatty and fried foods. Fast food, smoked meats and pickled dishes are also completely excluded. Dinner on the eve of the study must be light. It is optimal if it consists of a protein dish, complemented by a side dish of any cereal. Vegetables and fruits should be limited before ultrasound, they can lead to increased gas formation, and the presence of gases in the abdomen will not allow the ultrasound doctor to examine the fetus and all membranes well.

Also, 2-3 days before the ultrasound examination, legumes and all types of cabbage are necessarily excluded. The use of kvass or carbonated drinks also significantly increases gas production. It is better that on the eve of the scheduled test and ultrasound, all food should be as light as possible, but nutritious.

It is very important for a pregnant woman to eat enough protein even before the procedure. laboratory research.

Physical activity can also lead to inaccurate results. Doctors have long noticed that simply climbing stairs can provoke a change in biochemical parameters. In order for the results of laboratory tests to be accurate, the expectant mother should limit all physical exercise. In this case, it is better to postpone cleaning the apartment or attending yoga for pregnant women for a few days after the screening.

Biochemical tests should be done necessarily on an empty stomach. Some experts allow expectant mothers to drink some water before the study. Do not eat breakfast before going to the laboratory.

Testing should be done in the morning. Studies conducted in the evening give less truthful results.

Currently, doctors recommend that expectant mothers should limit all highly allergenic foods before taking biochemical tests. This is due to the fact that every day there are more and more scientific studies that indicate that such food can affect the receipt of reliable results.

For a week before screening tests for the 2nd trimester, it is better to exclude all citrus fruits, seafood, chocolate and honey from your menu.

Analysis norms

Biochemical screening of the 2nd trimester has a very important diagnostic value. The results of the obtained blood tests are not yet a diagnosis at all, they only help doctors to orient themselves in the possible pathologies of the course of pregnancy and anomalies in the development of the fetus at this stage of its intrauterine development. HCG is an important laboratory marker that allows you to identify certain "hidden" pathological conditions. Its dynamics throughout pregnancy changes. In the first weeks of intrauterine development of the fetus, the concentration of this hormone in the blood is maximum. Then, over time, it begins to decline.

Before childbirth, the concentration of hCG in the blood drops rapidly.

At the 16th week of pregnancy, normal levels of hCG in the blood reach 4.7-50 ng / ml. By week 20, this value is already rising above 5.3 ng / ml. Quite often, an increase in hCG occurs with multiple pregnancies. A significant excess of this indicator may indicate the possible development of Down's disease or Edwards syndrome.

Alpha-fetoprotein is another specific pregnancy hormone that is used to assess the intrauterine development of an unborn baby. It is formed due to the gastrointestinal tract and liver of the fetus. By the end of 10-11 weeks, it begins to flow through the common uteroplacental blood flow system and into the maternal body. The normal values ​​​​of this indicator at 16-19 weeks of gestation are 15-95 units / ml.

Free estradiol is the third indicator that shows how well a particular pregnancy is going. To a greater extent, it reflects the functional ability of the placenta. The normal course of pregnancy is accompanied by a gradual increase in this hormone in the blood of the expectant mother. By week 16, the values ​​​​of this hormone are 1.17-5.5 ng / ml.

To assess the risk of various chromosomal pathologies, doctors are increasingly prescribing a non-invasive hemotest to expectant mothers. It allows you to identify the DNA of the fetus and assess the presence of any genetic diseases. Significant disadvantages of this study are the possibility of conducting it only in the largest Russian cities and the high cost.

Such studies are prescribed only for strict genetic medical indications.

Interpretation of ultrasound results

The second trimester of pregnancy is the time when it is already possible to determine not only the outlines of the body of the fetus, but also to evaluate the work of its internal organs. For this, doctors have developed a number of special indicators. They help doctors conduct a more comprehensive assessment. Expectant mothers should remember that the conclusion of an ultrasound scan is not a diagnosis. It only describes all the visual changes that the specialist saw during this study.

How is second trimester screening done?

The second trimester of pregnancy for many women is marked by screening, a triple test for fetal chromosomal abnormalities. This study is considered slightly less informative than that which is carried out at the end of the first trimester. But nevertheless, biochemical screening of the 2nd trimester and ultrasound can and are considered as objective data for calculating risks and even making an accurate diagnosis.

What is this study, what is its information content, can there be errors? Screening of the 2nd trimester is a complex of medical measures, a blood test from a vein and ultrasound, the results of which are entered into a computer program that calculates the risks of Down syndrome, Edwards, Patau, Turner, triplodia and others.

At the same time, the interpretation of the results of biochemical screening of the 2nd trimester is issued by the program in the form of a quantitative risk. For example, “Down syndrome is 1:1800. And this means that one woman out of 1800 of the same age, with the same features of the course of pregnancy, the results of ultrasound and blood tests, has a child with this pathology.

Since simply risk numbers are not taken seriously by many women, they decide to undergo only a part of this examination. Namely, ultrasound screening of the 2nd trimester, which can clearly show malformations of the organs and systems of the fetus, suggest a genetic disease based on some markers, such as a shortening of the nasal septum or the absence of a phalanx of the little finger. In addition, prenatal screening of the second trimester makes it possible to diagnose obvious congenital malformations of the face, heart, stomach, brain and spinal cord, urinary system and kidney integrity. Many of these pathologies are indications for artificial termination of pregnancy, as they are not subject to surgical treatment and make the fetus unviable. Some markers that indicate genetic abnormalities can also be identified, but not always. For example, renal pyelectasis, hyperechoic inclusions in the heart, hyperechoic intestines, etc. These markers require re-examination. And blood screening of the 2nd trimester is very useful in this case. But even if the screening results are good, the ultrasound is repeated after 2-3 weeks. It is highly desirable to make an expert-class ultrasound, consider problem areas, including in 3D mode, so the information received will be more accurate.

Screening of the 1st trimester and the second screening during pregnancy differ in the methods of conducting. So, at the first screening, it is very important to accurately meet the deadlines for the delivery of a blood test and ultrasound. This must be done on the same day. And the timing of the second screening during pregnancy for ultrasound and biochemical analysis is different. So, the expectant mother donates blood for alpha-fetoprotein (AFP), free β-hCG and extriol for a period of 16-18 weeks. This deadline must be met! But ultrasound is most informative for a period of 20 weeks. At the same time, only biochemical screening is effective by no more than 70%. That is, about 30% of favorable blood test results turn out to be false negative, those who donate them will have children with Down syndrome or Edwards syndrome.

At the same time, adverse screening results of the 2nd trimester are usually an indication for invasive diagnostics. For longer periods, this is either amniocentesis (at 16-20 weeks) or cordocentesis (more than 20 weeks). Moreover, amniocentesis is less dangerous in terms of complications in the form of spontaneous late miscarriage or premature birth. Sometimes it happens that screening of the 2nd trimester of the norm by ultrasound shows, but a child with a syndrome is born ... The reason for this is the absence of any markers of chromosomal pathologies, poor visualization during ultrasound examination, and sometimes even the doctor's inattention.

Many women are poorly versed in how they do ultrasound screening for the 2nd trimester, blood tests are taken. And they try to pass these examinations on their own. Mistaken timing, getting blood test results without calculated risks - all this makes screening completely unreliable. After all, deciphering the results of screening of the second trimester is the task of a special computer program and not a pregnant woman or even her doctor. By the way, in this case it is not necessary to perform a biochemical blood test for all expectant mothers in a row. Coupons are usually issued only to those who had a poor first screening, the second screening during pregnancy is clarifying.

It is also necessary to undergo this examination for women over 35-40 years old, and regardless of whether they have their own children, those suffering from alcoholism and (or) drug addiction, those who have experienced a severe viral disease in the early stages of gestation, those who already have children born with a chromosomal pathology, with a closely related marriage, as well as taking medicines having a toxic effect on the fetus.

Factors such as IVF, multiple pregnancies, maternal diabetes, too little or big weight women, some bad habits.

Deciphering the results of 2nd trimester screening procedures helps to identify the risk of having a baby with a chromosomal disease, with a neural tube defect or other pathology.

Screening in the 2nd trimester is also the right time to check the level of fetal hormones, in particular liver and placental hormones, due to which it is possible to obtain detailed data on the development of the unborn baby.

Perinatal screening of the second trimester - deciphering this name, incomprehensible to expectant mothers, may sound simpler: conducting a comprehensive examination of the fetus with the possibility of detecting pathologies at the gene and chromosomal levels.

Assign a second screening during the second trimester of pregnancy.

But, despite the fact that the ideal period for its passage is the period of 16 - 18 weeks, expectant mothers can undergo it, starting from 14 weeks of pregnancy to 20.

This type of comprehensive examination necessarily consists of ultrasound (if necessary with Doppler) and a triple biochemical screening test.

2nd trimester screening is considered an additional examination. If the doctor conducting the pregnancy sees that the position of the expectant mother is normal, a second screening may not be necessary.

In most cases, this complex procedure is carried out on a paid basis, but this does not reduce the number of people who want to undergo 2nd screening and receive confirmation that their unborn child is healthy.

The first step is an ultrasound. Deciphering its results allows you to get information about the general condition of the unborn child and clarify the gestational age.

If, during the passage of an ultrasound, the doctor revealed deviations from the norm in the development of the fetus, then the pregnant woman is prescribed an ultrasound with Doppler.

This type of procedure allows you to judge the patency of blood vessels. This method examines the uteroplacental blood flow, the blood flow of the umbilical cord arteries, as well as the blood flow of the fetal brain.

At the same time, experienced specialists argue that in order to obtain an accurate diagnosis of a deviation from the norm, a pregnant woman must undergo an ultrasound with Doppler twice, the second time after two weeks, and best of all on a different device.

After passing the ultrasound of the second trimester, on the same day, a biochemical blood test is done.

A pregnant woman donates blood from a vein for a “triple test”, the results of which allow us to determine the level of the following substances in the blood:

1. HCG (chorionic gonadotropin) is a hormone. Present only in pregnant women. It is hCG that allows you to find out about the onset of pregnancy using a home express test;
2. AFP (alpha-fetoprotein) is a protein. In the required amount, it provides protection to the developing baby from the risk of a threat from maternal immunity;
3. NE (free, unbound or unconjugated estriol) is a steroid hormone. The main estrogen that contributes to the normal metabolism between the two organisms - mother and child.

Deciphering the results of ultrasound of the second screening

Since a routine ultrasound examination of the second trimester can call into question the normal development of the fetus, the expectant mother is prescribed an ultrasound with Doppler.

The procedure does not require special preparation, so Doppler or Doppler sonography can be done at any convenient time.

Doppler ultrasound and dopplerography - both of these procedures allow you to evaluate blood flow.

All data are visualized on the screen in the form of a graphical and color image of velocity curves, only during Dopplerography the recording is recorded on a tape, which allows you to control the change in blood flow for the worse or better after treatment.

The interpretation of the results of the second trimester ultrasound with Doppler can be as follows:

• assessment of the blood flow of the uterine vessels;
• assessment of the umbilical arteries;
• assessment of the middle vessel of the fetal brain.

Assessment of the state of the uterine vessels occurs using IR (resistance index).

The specialist determines the state of blood flow in the right and left arteries of the uterus, when evaluating only one of them, the results are false and far from normal, which can subsequently seriously harm the mother and her baby.

This fact is explained by the fact that with gestosis (toxicosis), the blood flow is disturbed in only one artery.

On this account, there is the following theory: if the blood flow is disturbed in the right vessel of the uterus, then the expectant mother may develop toxicosis in the third trimester of pregnancy.

Very often, late preeclampsia is accompanied by negative ensuing consequences. For a period of 20 weeks, the average IR of the uterine vessels can be 0.52; the allowable IR is 0.37 - 0.70.

An examination of the vessels of the umbilical cord is performed under two conditions: first, the fetus is in a calm state; the second - the heart rate is 120 - 160 beats / min.

This fact is due to the fact that if the results of heart rate deviate from the required norms, a decrease or increase in the resistance index in the umbilical arteries occurs.

The umbilical cord has three main blood vessels: 1 vein and 2 arteries. The purpose of ultrasound is to identify a possible anomaly in the form of 1 artery and 1 vein.

In this case, the fetus will experience a lack of oxygen and nutrition, which will adversely affect the growth and development of the unborn child.

IN specific cases the fetus adapts to such conditions, as a result, healthy babies are born, but with a low weight.

If one vessel functions, in which the blood flow is disturbed, one should not hope for a positive outcome of gestation and childbirth.

A pregnant woman needs to urgently undergo an expert ultrasound examination in the direction of a doctor and donate blood for chromosomal abnormalities.

The pathology of the middle artery of the brain makes the unborn baby suffer: his poor health is determined by the level of decrease in PI (pulsation index) in the vessels of the brain.

If a child has a hemorrhage in the skull, then there is an increase in IR in the arteries of the brain. At the 20th week of pregnancy, the average rate of PI in the cerebral artery is 1.83; the allowable indicator is 1.36 - 2.31.

Deciphering the results of the "triple screening test"

Receiving the results of a blood test from a vein, experts compare them with the established norms of the current trimester, on the basis of which they judge the course of the pregnancy and the health of the unborn child.

HCG norms of the second screening for the term:

• 16 weeks: 10,000 - 58,000 ng / ml;
• 17-18 weeks: 8,000 - 57,000 ng / ml;
• 19 weeks: 7,000 - 49,000 ng / ml.

Minor deviations of hCG from the norm during the second trimester screening are not of diagnostic value.

If a biochemical analysis revealed an elevated level of hCG, then this fact may indicate a multiple pregnancy.

In this case, conducting a “triple screening test” does not make sense at all, since all results will be inflated.

Also, the reason for the increase in this hormone in the blood can be reduced to the presence of a chromosomal pathology of the fetus or diabetes in a pregnant woman.

If a biochemical analysis revealed a low level of hCG in the second trimester of pregnancy, this may be a symptom of a chromosomal abnormality or missed abortion.

AFP (alpha-fetoprotein) norms for the term:

• 12 - 14 weeks: 15 - 60 units / ml;
• 15 - 19 weeks: 15 - 95 units / ml;
• 20 weeks: 27 - 125 units / ml.

The deviation of AFP from the norm in the form of a decrease in protein production in the gastrointestinal tract and liver of the fetus gives reason to assume the development of Down syndrome or Edwards, as well as an incorrectly indicated gestational age.

An elevated level of AFP is considered a sign of pathology in the development of the neural tube, craniocerebral or umbilical hernia, liver necrosis caused by a viral infection.

Norms of NE (free estriol) for the term:

• 13-14 weeks: 5.7 - 15 ng / ml;
• 15-16 weeks: 5.4 - 21 ng / ml;
• 17-18 weeks: 6.6 - 25 ng / ml;
• 19-20 weeks: 7.5 - 28 ng / ml;

If a biochemical screening test detected a deviation of NE from the norm in the form of an increase in its level in the blood of a pregnant woman, then this may be a symptom of multiple pregnancy, big size fetus or liver dysfunction.

The second screening does not apply to mandatory procedures; doctors prescribe it to pregnant women in order to confirm or refute the results of the first examination. The data obtained during the screening are carefully studied, checked for compliance with normal indicators, because from them parents will reliably find out how correctly and fully the child develops in the womb.

If the results of the second study are positive, then the embryo is absolutely healthy, has no genetic pathologies, feels good, if negative, then most likely the child suffers from a serious illness. Having determined the disease, the doctor either takes up intrauterine treatment of a small patient, or artificially causes premature birth. That is, screening of the 2nd trimester during pregnancy can be called a responsible and important procedure, which cannot be taken lightly and disregarding.

What is the purpose of 2nd screening during pregnancy?

Currently, gynecologists advise all pregnant women to undergo both the first and second screening in order to timely detect genetic abnormalities in the embryo. Each future mom hopes that her beloved and long-awaited baby grows and develops correctly, does not have any terrible diseases. But, unfortunately, not only strong and healthy children are born, but also babies with severe and incurable pathologies.

Screening is considered the most accurate examination, the results of which can be trusted.

Screening of the 2nd trimester during pregnancy allows you to detect fetal malformations that are indistinguishable during the first study, confirm or refute the diagnosis made in the 1st trimester, and identify physical abnormalities in the child.

How is the second pregnancy screening done?

When the 18th - 20th week of pregnancy comes, doctors advise patients to undergo 2 screenings and ultrasound. An examination is prescribed during this period of pregnancy for a reason, since it is at this time that it is convenient to study the embryo. The first screening, carried out in the middle of the first trimester of pregnancy, does not provide accurate information about the physical condition of the child in the womb, but only shows how well the embryonic development proceeds. But on the other hand, the second screening and ultrasound at week 20 can be very valuable data on the health of the fetus for the gynecologist. Having received negative results of the study, the doctor offers parents two options for further action: either give birth to a sick child, or, before it is too late, agree to an abortion. Translated from English, screening is sifting, that is, calculating the probability of having children with certain abnormalities. The most popular screening program is PRISCA, or Perinatal Risk Assessment. It usually includes three studies.

1. Biochemical triple test. In a pregnant woman during the 2nd trimester of gestation, venous blood is taken to check the content of AFP, hCG, and estriol markers. AFP, or alpha-fetoprotein, is a protein synthesized by the liver and digestive tract of the fetus. HCG, or human chorionic gonadotropin, is a hormone produced in the embryonic membranes, present only in the blood of pregnant women. The sex hormone estriol is produced by the ovarian follicular apparatus. A biochemical test allows you to determine the likelihood of an embryo developing such severe chromosomal diseases as Down syndrome and Edwards syndrome. For a pregnant woman, the study is completely safe, the concentration of AFP, hCG, estriol is simply calculated in the blood, no manipulations are performed on the woman's body.
2. Ultrasonography. Ultrasound as part of screening is performed more accurately and in detail compared to conventional ultrasound. The medical specialist very carefully examines the image of the embryo on the monitor of the ultrasound machine. The doctor can find in the fetus both minor physical defects that are easily cured with medications or surgical operations, and serious developmental anomalies that cannot be eliminated. Usually, by means of ultrasound during the second screening, it is not difficult to diagnose a hernia in the diaphragm, clubfoot, cleft lip, cleft palate, shortening of the tubular bones, deformity of the fingers, and many other pathologies.
3. Cordocentesis. This procedure is not a mandatory step in the second screening. But if a blood test and ultrasound show the presence of some abnormalities, then cordocentesis is still recommended. The operation is quite complicated, but it is it that allows you to find out what is wrong with the baby in the womb. A special needle is inserted into the belly of a pregnant woman, with the help of which the blood of the embryo is taken from the umbilical cord. The collected blood is sent to the laboratory for analysis, according to the results of which the doctor makes an accurate diagnosis of the fetus. But it must be said that cordocentesis is an unsafe procedure. Two out of a hundred women have a miscarriage after surgery. Often the needle leaves behind a hematoma, which, however, quickly resolves. One woman out of a hundred after the procedure becomes infected with an infection.

What diseases can be detected in the embryo during the second screening?

Many women wonder if it is necessary to carry out 2 screening during pregnancy. Research is not cheap. But will the spent cash? In fact, second trimester screening should not be underestimated, as it provides parents with important information about their baby as it develops in the womb. According to the results of the study, the family decides whether to keep the baby or have an abortion. If the embryo is seriously and terminally ill, then it is better not to torment him, but to artificially terminate the pregnancy. Until the end of the second trimester, abortion is still allowed. Some mothers are concerned about the moral side of the issue. In this case, you should think about how difficult it is to raise and educate children with disabilities. Are parents willing to take on this burden for life? Or is it still better to postpone the birth of a child? Usually screening of the second trimester is carried out to detect such anomalies in the development of the embryo: neural tube defect, Down syndrome, Edwards syndrome, Patau syndrome.

• Neural tube defect. On the twentieth day of intrauterine existence, the neural plate appears in the embryo. After a few days, it folds into a tube - the rudiment of the central nervous system, including the brain and spinal cord. The formation of the tube occurs very slowly, sometimes the plate does not close completely or straightens out. In this case, severe fetal malformations occur: anencephaly, cephalocele, meningocele. Anencephaly, or pseudocephaly - the absence of the cerebral hemispheres, the temporal and occipital parts of the skull. The midbrain and diencephalon are deformed, the eyes are bulging, the tongue is unnaturally long, the neck is short, the upper part of the head, instead of the skull, is covered with a dense membrane dotted with blood vessels. Cephalocele, that is, splitting of the skull - the exit of brain tissue to the outside through defects in the skull. Meningocele is a median anomaly of the spine in which the contents of the spinal canal are not completely closed.
• Down Syndrome. This chromosomal disorder, also called trisomy, occurs at the time of conception. In a sick fetus, the karyotype does not include 46 chromosomes, as in a healthy person, but 47. In Down syndrome, the twenty-first pair of chromosomes is actually a triple, not a pair. Such a genetic anomaly occurs when, during fertilization, an egg or sperm carries an extra chromosome. Newborns with Down syndrome have a small head, a flattened face, deformed ears, a flat nose, slanting eyes, a short neck, an always open mouth, and short limbs. The occurrence of the disease does not depend on race, lifestyle, health, age of the parents. It is impossible to predict and prevent a chromosomal mutation.
• Edwards Syndrome. This disease, like Down's syndrome, occurs at conception, is the result of a change in the karyotype. Only the extra third chromosome is located not in the twenty-first, but in the eighteenth pair of chromosomes. Newborn babies with Edwards syndrome are weak, sore, undersized and underweight. They look premature, but are born late. Affected children have a short sternum, deformed ribs, dislocated hips, clubfoot, crooked fingers, papillomas on the skin. Infants with Edwards syndrome have a specific head structure, they have a low forehead, a short neck, underdeveloped eyeballs, a bulging nape, low-lying ears, deformed auricles, a small mouth, and a cleft lip. With this disease, almost all systems and organs do not work properly, heart defects, intestinal obstruction, kidney failure, hernia in the inguinal region, fistulas in the esophagus, bladder diverticula occur. Affected children rarely live past their first birthday.
• Patau syndrome. This disease is characterized by the presence of serious congenital malformations. The body weight of newborns diagnosed with this disease does not exceed 2.5 kg. Children have disorders in the development of various parts of the central nervous system, moderate microcephaly, pathologies of the visual system (clouding of the cornea, coloboma, microphthalmia, etc.), polydactyly, developmental disorders of the hands. Children with Patau syndrome often have a sloping, low forehead, narrow palpebral fissures, a broad base of the nose and a deep bridge of the nose, pinna anomalies, a short neck, cleft palate, and upper lip. More than half of babies suffer from malformations of the heart muscle - disorders in the development of the cardiac septa and the position of blood vessels are common. Children are diagnosed with disorders in the development of pancreatic tissues, embryonic hernia, doubling or enlargement of internal organs (spleen, kidneys, etc.), malformations of the organs of the reproductive system. Cysts, increased lobulation of the cortical tissue of the kidneys may be present. Mental retardation characteristic of SP is noted. These severe developmental pathologies prevent most infants (95%) with Patau syndrome from surviving beyond a few weeks or months. In rare cases, it is possible to maintain the life of such patients for several years. In developed countries, there is a trend towards extending the life expectancy of children with Patau syndrome up to five years.

It is worth noting that, although the above pathologies occur extremely rarely, they are distinguished by insidiousness and unpredictability. It is impossible to prevent chromosomal mutations, they appear at the time of conception, are not treated, do not disappear on their own, remain for life. Sick children cannot live fully, suffer from their own handicap, depend on close people, and are disabled. The bad news is that diagnosing chromosomal diseases in an embryo in the womb is a difficult task for medical professionals.

Even if a second screening for the most accurate and modern methods, it is not always possible to make a reliable and final diagnosis. In most cases, doctors simply tell parents how likely they are to have a child with a disability. And the family already decides whether to keep the pregnancy or not.

When is the second screening?

It is extremely important not to miss the timing of the second screening. Usually, doctors recommend that patients undergo an examination no earlier than the 16th week of pregnancy, but no later than the 20th week. If the screening is done early, then if a pathology is found in the embryo, it is not so dangerous to have an abortion. If you pass the examination later, you can get more accurate and reliable results.

Medical professionals believe that the most optimal timing the second screening is 17 - 19 weeks of pregnancy. At this time, it is convenient to study the state of the embryo in the womb, and it is still possible to artificially terminate the pregnancy.

How to prepare for the second screening?

Preparing for the second screening is usually not difficult, as women already have experience with the first screening. It can be difficult morally only for mothers who received not encouraging results during the screening of the first trimester. It is not easy to calm anxiety and a bad feeling, but you need to try to do it. Before the second examination, the bladder and intestines can not be emptied, the fullness of the organs with urine and feces does not affect the results of the ultrasound. One day before screening, foods that can cause allergies should be excluded from the menu: citrus fruits, chocolate. On the day of donating blood for analysis, you should starve, as eating can make the laboratory test results false.

How is the diagnosis established by the results of the second screening?

Screening of the 2nd trimester during pregnancy is carried out within one day. After the examination, the doctors prepare the test results for several weeks. As a result, a medical report falls into the hands of parents, consisting of a rather impressive list of digital data, which is not easy for an uninformed person to understand. By what numbers deviate from normal values, doctors determine what kind of disease the embryo suffers in the womb. An excess or insufficient amount of AFP, hCG or estriol in the mother's blood indicates a specific anomaly in the development of the fetus. Normal 2nd screening and ultrasound results should be as follows:

16 weeks pregnant

1. Embryo weight - 100 g.
2. Body length - 11.6 cm.
3. Tummy circumference - 88 - 116 mm.
4. Head circumference - 112 - 136 mm.
5. Fronto-occipital size - 41 - 49 mm.
6. Biparietal size - 31 - 37 mm.
7. The length of the leg bone is 15 - 21 mm.
8. The length of the femur bone is 17 - 23 mm.
9. The length of the forearm bone is 12 - 18 mm.
10. The length of the shoulder bone is 15 - 21 mm.
11. The amniotic fluid index is 121.
12. The content of alpha-fetoprotein - 34.4 IU / ml.
13. Estriol content - 4.9 - 22.7 nmol / l.

17 weeks pregnant

• Embryo weight - 140 g.
• Body length - 13 cm.
• Tummy circumference - 93 - 131 mm.
• Head circumference - 121 - 149 mm.
• Fronto-occipital size - 46 - 54 mm.
• Biparietal size - 34 - 42 mm.
• The length of the leg bone is 17 - 25 mm.
• The length of the thigh bone is 20 - 28 mm.
• The length of the bone of the forearm is 15 - 21 mm.
• The length of the shoulder bone is 17 - 25 mm.
• Amniotic fluid index - 127.
• The content of chorionic gonadotropin - 10 - 35 thousand.
• The content of alpha-fetoprotein - 39 IU / ml.
• Estriol content - 5.2 - 23.1 nmol / l.

18 weeks pregnant

1. Embryo weight - 190 g.
2. Body length - 14.2 cm.
3. Tummy circumference - 104 - 144 mm.
4. Head circumference - 131 - 161 mm.
5. Fronto-occipital size - 49 - 59 mm.
6. Biparietal size - 37 - 47 mm.
7. The length of the leg bone is 20 - 28 mm.
8. The length of the femur bone is 23 - 31 mm.
9. The length of the forearm bone is 17 - 23 mm.
10. The length of the shoulder bone is 20 - 28 mm.
11. The amniotic fluid index is 133.
12. The content of chorionic gonadotropin - 10 - 35 thousand.
13. The content of alpha-fetoprotein - 44.2 IU / ml.
14. Estriol content - 5.6 - 29.7 nmol / l.

19 weeks pregnant

• Embryo weight - 240 g.
• Body length - 15.3 cm.
• Tummy circumference - 114 - 154 mm.
• Head circumference - 142 - 174 mm.
• Fronto-occipital size - 53 - 63 mm.
• Biparietal size - 41 - 49 mm.
• The length of the leg bone is 23 - 31 mm.
• The length of the femur bone is 26 - 34 mm.
• The length of the forearm bone is 20 - 26 mm.
• The length of the shoulder bone is 23 - 31 mm.
• Amniotic fluid index - 137.
• The content of chorionic gonadotropin - 10 - 35 thousand.
• The content of alpha-fetoprotein - 50.2 IU / ml.
• The content of estriol is 6.6 - 38.5 nmol / l.

20 weeks pregnant

1. Embryo weight - 300 g.
2. Body length - 16.4 cm.
3. Tummy circumference - 124 - 164 mm.
4. Head circumference - 154 - 186 mm.
5. Fronto-occipital size - 56 - 68 mm.
6. Biparietal size - 43 - 53 mm.
7. The length of the leg bone is 26 - 34 mm.
8. The length of the femur bone is 29 - 37 mm.
9. The length of the bone of the forearm is 22 - 29 mm.
10. The length of the shoulder bone is 26 - 34 mm.
11. The amniotic fluid index is 141.
12. The content of chorionic gonadotropin - 10 - 35 thousand.
13. The content of alpha-fetoprotein - 57 IU / ml.
14. Estriol content - 7.3 - 45.5 nmol / l.

If the fetus has Down syndrome, then the content of hCG in the blood of a pregnant woman is high, and AFP and estriol are low. With Edwards syndrome, the concentration of all substances is below normal. With a neural tube defect, chorionic gonadotropin is normal, and estriol and alpha-fetoprotein are high. Also, a high content of AFP can mean a developmental disorder in the embryo of the spinal cord, and a low content can mean Meckel-Gruber cider, liver necrosis, occipital hernia, spina bifida. If the concentration of estriol in the blood is very low, then a miscarriage is likely. But with a negative result of the study, parents should not despair. Doctors, when they do 2 screening during pregnancy, warn that it is impossible to make a 100% accurate diagnosis. It happens that, despite the unfavorable prognosis of doctors, healthy and full-fledged children are born to women.

Why does second trimester screening sometimes give false results?

Doctors are people too, and sometimes they make mistakes. When making a diagnosis, doctors are guided by the numerical indicators of the norm, but the body of each woman is individual, and even significant changes in the blood levels of AFP, hCG, estriol do not always indicate pathology. You should not try to figure out the results of the examination on your own, and even more so to diagnose the child in the womb. This occupation is better to entrust the gynecologist. It is not easy to decipher the final data of the second screening, and an experienced medical specialist, at one glance at the numbers, perfectly sees the whole situation. It happens, although rarely, that the study shows false results, which is due to certain reasons. Therefore, before screening, the doctor must interview and question the patient in order to weed out possible factors that affect the veracity of the examination indicators. A false result is possible in the following cases:

• with multiple pregnancy;
• when conceived by IVF;
• with obesity or, conversely, underweight;
• with diabetes;
• with an incorrectly determined gestational age.

Should I do a 2nd trimester screening?

To undergo a second screening or not is a purely personal decision. The expectant mother must take it on her own.

Sometimes the reluctance to undergo screening for the 2nd trimester is associated with internal experiences. These experiences may not be just like that, because it happens that screening studies give erroneous results and identify threats for the development of pathologies in a fetus that is developing quite normally.

False results make the expectant mother nervous and worried about the baby for the rest of the gestation period. And this, in turn, leads to a negative course of pregnancy and can affect the health of the expectant mother and fetus. Fortunately, the situation is not at all hopeless. If a pregnant woman is afraid of invasive diagnostic methods that provide the most reliable information about the presence or absence of abnormalities, she can resort to safe non-invasive prenatal DNA tests.

If a woman does not fall into the risk group or has no complications during pregnancy, then the leading doctor suggests undergoing only an ultrasound procedure. In Russia, the second screening has not been practiced for about two years. However, the absence of negative results in the first trimester does not guarantee that there are no risks in the second trimester. Of course, it is not advisable to prescribe additional tests to every woman who is expecting a child. This only provokes women to worry and it is pointless to spend family funds.

The choice of the family, if the results of the 2nd screening and ultrasound turned out to be poor, is small: save the life of a sick child or agree to an abortion for medical reasons, while the term still allows for this operation. Such a decision cannot be considered a moral crime, since the reasons for it are quite reasonable. A family that, for moral or material reasons, cannot take care of a child with serious disabilities will be able to prepare for a new pregnancy in the future and give birth healthy child. This is much more reasonable than exposing yourself and the crumbs to life's trials.

There are also families who treat the baby as a divine gift, because it does not matter how he will be born. For such couples, abortion is an even greater disaster than the birth of a baby with pathologies. Therefore, families who are happy to give their baby their love and protection can refuse screening without fear.

Under any circumstances, the conclusion must be made soberly, and not under the influence of emotions. If in doubt whether second trimester screening is necessary and when to get screened, it is best to consult with your doctor, based on previous test data.

In what cases is it necessary to do 2 screening?

If a woman feels well, pregnancy is not accompanied by complications, then a second screening is not necessary. But if the expectant mother wishes to undergo an examination to make sure that everything is in order with the precious baby in her stomach, then the doctors have no right to refuse her. But there is a category of pregnant women who cannot ignore the screening of the second trimester, since the risk of severe malformations in the embryos they carry is high. Mothers need to be screened for:

1. over 35 years old;
2. having a bad heredity;
3. recovering from a viral disease at the beginning of pregnancy;
4. married to a close relative;
5. addicted to drugs;
6. abusing alcohol;
7. working in hazardous conditions;
8. taking strong medications;
9. previously had an abortion;
10. survivors of a miscarriage or stillbirth.