– mass examination of women, which is done at 11–13 weeks of pregnancy. The first screening allows us to identify congenital abnormalities of the fetus, as well as the risk of its birth with severe genetic disorders.

Screening in the first trimester includes an ultrasound examination and a biochemical blood test for specific indicators (β-hCG and PAPP-A). All pregnant women without exception are subject to screening. In this case, the woman has the right to refuse such an examination. But, it should be remembered that refusal of screening may lead to unfavorable pregnancy outcomes.

In what cases is screening necessary?

There are risk groups of pregnant women who must undergo prenatal diagnosis.

The first screening is carried out in the following cases:

• All women over 35 years of age.
• If there have been miscarriages or undeveloped (frozen) pregnancies in the past.
• In the presence of harmful occupational factors.
• Threat of miscarriage.
• If the family already has a child with congenital pathologies or chromosomal disorders. Or such abnormalities were diagnosed in previous pregnancies.
• Women who have had infectious diseases in the first trimester.
• Women who suffer from alcoholism, smoking or drug addiction.
• If there are hereditary diseases in the family of one of the parents.
• The presence of a family connection between the parents of the unborn child.
• Women who have taken pharmaceuticals that are contraindicated for use during pregnancy.

Procedure for the first screening

To undergo a reliable first screening, the 1st trimester has a certain framework for this. The first prenatal diagnosis is carried out from the 10th week of pregnancy until the 14th week. The most reliable indicators will be those obtained at weeks 11–12. It is very important that the deadline is set correctly. A gynecologist will do this and determine when it is best to undergo the first screening.

In order to undergo a perinatal examination, it is necessary to properly prepare for the examinations. If ultrasound is performed with a vaginal probe, then no special preparation is required. If an ultrasound is performed through the abdomen, the following rules must be observed:

• The bladder should be full.
• Do not urinate 4 hours before the ultrasound.

If an undeveloped pregnancy is detected on ultrasound, the examination is stopped.

For a biochemical blood test, preparation should be as follows:

• Before donating blood, it is necessary to do an ultrasound of the fetus. This is the most important condition, since the indicators in the biochemical blood test directly depend on the duration of pregnancy.
• It is necessary to take a blood test from a vein strictly on an empty stomach. If necessary, you can take food with you and eat after the blood test.
• A couple of days before the biochemical examination, it is necessary to exclude all potential allergens from the diet. They can be seafood, nuts of any kind, chocolate. You should also avoid eating spicy, fatty and smoked foods.

If the basic rules are not followed, the results of the first screening may be incorrect.

What pathologies can be detected during the first screening?

Screening in the 1st trimester reveals gross developmental disorders of the child and chromosomal pathologies. During screening, the following abnormalities can be detected or suspected:

• Down syndrome is the most common genetic abnormality.
• Lange's syndrome. It is characterized by multiple developmental defects. If the baby survives, then he has severe mental retardation.
• Patau syndrome. Characterized by severe damage to the child’s organs. Such children die in the first months after birth.
• Edwards syndrome. An ultrasound reveals an anomaly in the development of the umbilical vessels - 1 artery and 1 vein. Normally, the umbilical cord contains 3 vessels - 2 arteries and 1 vein.
• Malformations of the neural tube in the fetus.
• Omphalocele is a hernial protrusion in the area of ​​the umbilical ring, which includes internal organs.
• Anencephaly is the absence of a brain.

All interpretations based on the results obtained are made by a gynecologist.

Interpretation of ultrasound results at the first screening

At the first screening during ultrasound, the following indicators are assessed:

• The distance from the crown to the coccyx (KTR), which normally ranges from 33 to 73 mm, depending on the stage of pregnancy. Below is a table showing the CTE standards:

• Fetal TVP (nuchal translucency thickness).

Normally, TVP is from 1.5 to 2.7 mm. During screening, TVP is a very important marker of genetic disorders. The table below shows the TVP standards:

If the TVP result is more than 3 mm, then this can be regarded as a sign of Edwards or Down syndrome.

• Nose bone size.

This is a marker by which Down syndrome can be suspected. Determination of the nasal bone is necessarily included in the screening of the first trimester. According to ultrasound, the nasal bone is normally determined from 10 to 11 weeks. Bone size is assessed from 12 weeks. Normally, the nasal bone should be more than 3 mm. The absence of the nasal bone and an increase in TVP are a clear sign of Down syndrome.

• Biparietal size (BPR).

Ultrasound determines this size as the distance between the parietal tubercles. By the end of the first trimester, the BPR result is normally more than 20 mm.

• Fetal heart rate.

Heart rate also differs depending on when screening is done in the first trimester. Normal heart rate ranges from 150 to 180 beats per minute.

• The development of the internal organs of the fetus, umbilical vessels, and placenta is assessed.

Decoding the results of a biochemical blood test

After a successful ultrasound, it is necessary to take a blood test for the content of specific substances: β-hCG and PAPP-A. In addition, the MoM coefficient is calculated.

• Free β-hCG is a fetal specific hormone. Screening in the 1st trimester allows you to determine its maximum values. Determining the level of β-hCG allows you to most reliably calculate the risk of Down disease. Below is a table showing normal values ​​for β-hCG levels:

It is important to remember that normal β-hCG levels may vary from laboratory to laboratory.

• PAPP-A is a protein substance produced by the placenta. During gestation, the level of a specific protein constantly increases. Deviations from the normal values ​​presented in the table may indicate the presence of abnormalities in the child.

Do not forget that PAPP-A values ​​​​in each laboratory also differ.

• The MoM coefficient is calculated when determining β-hCG and PAPP-A. Can be used instead of standard units of measurement. Its indicators normally range from 0.5 to 2 from 9 to 13 weeks. If the MoM is below 0.5, then this may indicate a risk for Edwards syndrome in the child. When MoM exceeds 2, this indicates possible Down syndrome.

Calculation of perinatal risk

In order for first trimester screening to be as reliable as possible, tests and ultrasounds must be taken in one institution. The risk of deviations is calculated based on the results of β-hCG, PAPP-A, the age of the pregnant woman, individual characteristics of the body, harmful factors, and concomitant pathologies. The obtained data is entered into a computer, into a special program that calculates risks. The program produces the final result in the form of a fraction. For example, the program gave a risk of 1:400. The decoding will be as follows: out of 400 pregnancies with the entered indicators, 1 baby will be born with a pathology. Depending on the value obtained, conclusions may be as follows:

• Positive test. It means that during this pregnancy there is a high risk of having a child with a pathology. In this case, a genetic consultation is carried out. The issue of additional examination to establish or refute the diagnosis is being decided. In this case, amniocentesis or chorionic villus biopsy is performed.
• Negative test. This means that the risk of pathologies is low and there is no need to conduct additional examination. In this case, the pregnant woman undergoes routine screening in the 2nd trimester.

First trimester and screening for Down syndrome

Down syndrome in a fetus can be suspected as early as 10–11 weeks. When performing an ultrasound, the following characteristic signs of this syndrome are revealed:

• Thickening of the TVP is more than 3 mm. An abnormal TVP may also indicate other genetic disorders.
• Absence of the nasal bone in 70% of cases. It is important to know that even in healthy children in the early stages, the nasal bone may not be identified.
• Impairment of blood flow through the ductus botalli.
• Hypoplasia (reduction) in the size of the upper jaw.
• Bladder enlargement.
• Increased fetal heart rate.
• Pathology of umbilical cord vessels: one artery and one vein.

First trimester screening is an important stage of examination during pregnancy. With its help, you can exclude or identify severe pathologies in a child, often incompatible with his life. In order for the indicators to be reliable, it is necessary to follow the doctor’s recommendations and undergo screening within the prescribed period.

If screening results reveal a high risk of pathologies, do not panic. It is necessary to contact a specialist who will prescribe additional examination. It is important to remember that high risk is not a diagnosis, but only an assumption, which is often refuted after additional examinations.

Ultrasound screening is a full-fledged set of examinations that allows mom and dad to find out about the health status of the baby in the womb. This method allows you to see the presence or absence of many congenital diseases. It is usually done three times during pregnancy - in the first, second and third trimester. It consists of two procedures – ultrasound diagnostics and blood test.

First trimester screening consists of ultrasound and blood tests

The first screening is carried out between 11 and 14 weeks after the baby is conceived. The main objective of the method is to check the fetus for the presence of any developmental pathologies.

This type of testing even reveals complications in pregnancy that the expectant mother might not have suspected due to the absence of symptoms, good health, etc. This test is not always performed on pregnant women; other groups of people often undergo it.

For example, screening a group of children of the same age - the technique allows us to identify characteristic diseases for this age. Since it is usually prescribed only three times, women are frightened if a specialist refers it for additional screening.

There is no reason to panic, because doctors refer for additional examination not because a pathology has been detected, but because there is a risk of its development. For example, screening is often prescribed for women over 35 years of age if family members have pathologies, if there was a frozen pregnancy or miscarriage in the past, etc.

How is the study carried out and for how long?

To obtain reliable results, the first examination is scheduled between the eleventh and thirteenth weeks of pregnancy. You cannot undergo a test earlier or later than this, otherwise there is a chance that you will not see the pathology.

It is possible to refuse routine examinations during pregnancy, but this will be considered negligence towards one’s health. Such a decision carries risks for the child. By refusing scheduled checks, the woman is putting his life in danger.

The procedure consists of two stages:

1. Ultrasound diagnostics;
2. Blood biochemistry study.

There are rules for undergoing an ultrasound examination - the expectant mother must drink half a liter of ordinary, clean, still water an hour and a half before the examination. The bladder should be full during an ultrasound so that the specialist can better examine the position of the fetus and its condition. Instead of drinking water, you can avoid urinating three hours before the examination.

When a specialist uses the transvaginal method of examining the fetus, the sensor is inserted into the vagina, so the preparation described above is not required. However, it is advisable to go to the toilet before doing this.

After the ultrasound, a blood biochemistry test is performed. This order is mandatory, since blood counts can change very quickly, but if you undergo an ultrasound examination first, you can easily determine the baby’s condition.

A pregnant woman should go to donate blood with the results of an ultrasound, which will indicate the duration of pregnancy. Unfortunately, sometimes an ultrasound shows regression of pregnancy or fading, then blood donation will no longer be needed. To prepare for blood sampling, you need to drink only clean water, exclude food and any drinks - blood sampling takes place on an empty stomach.

The specialist will conduct an ultrasound, the results of which will confirm or refute the presence of pathologies

What can you learn from screening?

Often, specialists cannot immediately examine all the data, so they ask the expectant mother to turn on her other side, walk around, cough, or even squat. Thus the fetus changes position.

The specialist examines the following indicators:

1. Coccyx-parietal size, or CTP. It is carried out from the parietal point on the fetal head to the coccyx.
2. Biparietal size, or BDP, is a study of the distance between the tubercles of the crown area.
3. Measure the head circumference and the distance from the back of the head to the forehead.
4. They check the structure of the brain, whether the hemispheres are symmetrically located, and whether the cranium is closed.
5. The thickness of the collar zone, or TVP, is checked.
6. The frequency of contractions of the heart muscle, its size and the size of large vessels are studied.
7. Check the length of the bones of the shoulders, hips, lower legs and forearms.
8. The thickness of the placenta and its structure, as well as its location in the uterus.
9. The location of the umbilical cord and the number of vessels in it.
10. The amount of amniotic fluid.
11. Uterine tone.
12. Condition of the cervix.

If the study is carried out earlier than the eleventh week, then not all organs and bones are yet sufficiently formed for a specialist to be able to check them for abnormalities.

Starting with biochemistry, it is possible to determine some important indicators, for example, human chorionic gonadotropin β-hCG. This hormone is produced by the fetus. Interestingly, it is with its help that you can determine the presence of pregnancy.

Now you can conduct a 3D ultrasound examination

If a girl is pregnant and does a test, then a special substance on the test strip reacts to the presence of the hormone. From the beginning of the first days of pregnancy (if it proceeds without complications), the amount of hormone produced gradually increases, reaching a peak by the twelfth week. Then the hormone level begins to gradually fall. In the second half of the term, β-hCG levels remain unchanged.

Below is the norm for β-hCG levels by week:

• tenth – from 25.80 to 181.60 ng/ml;
• eleventh – from 17.4 to 130.3 ng/ml;
• twelfth – from 13.4 to 128.5 ng/ml;
• thirteenth – from 14.2 to 114.8 ng/ml.

If the indicators exceed the norm, then there are several options - the child has Down syndrome, the mother suffers from severe toxicosis, or she has diabetes.

If the readings are below normal, then this also indicates several problems: placental insufficiency, threatened miscarriage, ectopic pregnancy or Edwards syndrome in the child. Another important indicator in the blood is protein A. Protein is responsible for the proper development and functioning of the placenta.

Below is the norm for protein-A (PAPP-A) by week:

• tenth – from 0.45 to 3.73 mIU/ml;
• eleventh – 0.78 to 4.77 mIU/ml;
• twelfth – from 1.03 to 6.02 mIU/ml;
• thirteenth – from 1.47 to 8.55 mIU/ml.

When the readings are below normal, this may indicate the presence of abnormalities such as Down syndrome, Edwards syndrome or Cornelia de Lange syndrome. But there are also cases when an elevated protein level does not signal the presence of the pathologies listed above.

Rules for preparing for research

They always do an ultrasound first. There are two methods of ultrasound examination - transabdominal and transvaginal. The first is carried out, as usual, by moving the sensor over the pregnant woman’s abdomen. During the second, the sensor is inserted into the vagina.

In the first case, you must go to the procedure with a full bladder - drink about one and a half liters of clean water without gas in half an hour. The second method does not require any special preparatory measures. When the ultrasound results are released, the woman must donate blood for analysis. It is taken from a vein, so you must take it on an empty stomach and not drink drinks other than water.

To get the most reliable results, a pregnant woman three days before the analysis must exclude from her menu sweet, smoked, fried and fatty foods, as well as foods that cause allergies - citrus fruits, chocolate, nuts and seafood.

During a transabdominal examination, you need to drink one and a half liters of water or not go to the toilet for several hours

First trimester screening

As already written above, it is carried out no earlier than the eleventh, but no later than the thirteenth week. It is during this period that the so-called embryonic period of fetal development ends, and the fetal period begins.

This means that the embryo turns into a fetus, and organs begin to develop, like those of a full-fledged human being. During this period, pathologies or abnormalities can be identified.

Of course, only a specialist will correctly interpret the screening results, but expectant mothers can at least learn in general terms what to expect and what some indicators may mean.

Who is referred for first trimester screening?

You can refuse screening, but doctors do not advise it

All pregnant women are referred, but this procedure can be refused. Doctors do not recommend refusing, as this is a negligent attitude towards the baby’s life. The following groups of women should also be examined:

• over 35 years old;
• there were unsuccessful attempts to give birth - a fetus, a miscarriage;
• those who work in production and may come into contact with harmful substances;
• who gave birth to a child with disabilities in the past;
• during the first weeks, those who had an infection;
• taking medications prohibited for the first trimester;
• those suffering from alcoholism or drug addiction;
• when there is a threat;
• if there are pathologies in the family.

How the study is performed

There is a special medical worker - a sonologist, who carries out the procedure. At this time, there are two options - abdominal and transvaginal examination. They prefer the second one, as it is more reliable.

There are machines for home ultrasound

The woman is asked to undress to the waist and lie on the couch with her legs bent. Then a thin sensor in a condom is inserted into the vagina. It will be moved to fully examine the fetus, this may cause discomfort, but not pain. After the procedure, some discharge may appear on the underwear, perhaps a little bloody.

This is normal, no need to worry. Ultrasound of the abdominal area does not give reliable results at this stage, but if it is chosen, the woman is asked to lift her clothes to expose her stomach. Then you will have to wait for the results - in public hospitals for up to five days. After this, you need to donate blood for analysis.

Cost of 1st trimester screening

It is known that not even all government agencies are ready to provide such a service free of charge. Blood biochemistry alone exceeds one and a half thousand rubles, and you also have to pay for the ultrasound procedure itself. Each clinic sets the cost differently, but it is unlikely to be less than two thousand rubles.

Interpretation of 1st trimester ultrasound screening, norms and possible deviations

To accurately obtain reliable results, the following conditions must be met:

• the process occurs only from 12 to 13 weeks;
• the fetus must be in the correct position - if something is in the way, the doctor will ask you to move, then the baby will turn over;
• the coccygeal-parietal size (further in the article KTP) is at least 45 mm.

Various indicators, such as the length of the nasal bone, can indicate a child's disease

PAPP-A - what is it?

This indicator in biochemical analysis is a protein that is produced by the placenta. If its level is exceeded or is insufficient in the body of a pregnant woman, then this may be a signal of the development of a genetic pathology.

Human chorionic gonadotropin (hCG)

A hormone produced by the chorion. Immediately after conception, in the first hours, its level begins to rise. Until 11-12 weeks, the initial indicator increases thousands of times.
Then the production of the hormone slows down - somewhere at the beginning of the second trimester, and then remains unchanged.

An increase in the norm may indicate:

• Down syndrome;
• multiple pregnancy;
• development of diabetes mellitus in the mother;
• for toxicosis.

The deficiency indicates:

• Edwards syndrome in a baby;
• risk of miscarriage;
• placental insufficiency.

Remember, only a specialist can correctly determine the risk.

What is CTE during pregnancy on ultrasound

This coccygeal-parietal size indicates the correct development of the baby inside the mother’s womb. The size of the CTE is compared with the weight of the child and the gestational age. It is believed that the higher this indicator, the longer the gestational age.

KTR norms

When the CTE is higher than normal, it means that the child at birth will weigh more than 3-3.5 kilograms.

But if the indicator is lower, then:

1. There is a risk that the pregnancy develops abnormally. Then you should check the baby's heartbeat to make sure that he did not die in the womb. If this happens, urgent hospitalization is necessary.
2. It is possible that few hormones are produced, especially progesterone. In this case, the specialist sends for further examination and prescribes medications.
3. Mom may suffer from an infectious disease, even a sexually transmitted disease.
4. There is a genetic deviation.

In some cases, low CTE signals an incorrectly set gestational age.

Fetal BDP (biparietal size)

This way the size of the fetal head is measured. It is this indicator that is considered the main one when determining the correctness of child development.

This indicator also determines whether the birth will be normal or whether a caesarean section will have to be performed. If the head is too large, then the mother will not be able to give birth in the usual way, only through caesarean section.

Neck thickness (TCT)

This place is located between the neck and the upper skin membrane of the fetal body; there is an accumulation of fluid in it. This indicator begins to decrease from the 14th week, and by the 16th it is practically not visible. There are standards that indicate the presence or absence of deviations. To do this, measure the thickness of this space.

The timing of screening is determined by the timing of fetal development

Signs of Down syndrome, as well as Edwards and Patau syndromes

A sign of Down syndrome can be considered a decrease in the level of protein-A (PAPP-A), low or high hCG. These same signs can also signal Edwards syndrome; therefore, in case of such results, the pregnant woman is sent for additional examinations.

Nasal bone at 12 weeks, normal chart

With a genetic deviation, it develops incorrectly, or rather ossifies later than usual. If it is too small or absent at all, there may be a developmental anomaly. There is a special table of standards.

Heart rate (HR)

In the first stages of life, it is normal when the baby’s heart rate is equal to the mother’s pulse rate - about 83 beats. But the longer the term, the higher the frequency of reductions. Every day, approximately three beats per minute will increase. Closer to the 9th week, the frequency is 175 beats per minute.

What can distort the result

False positive results occur in the following cases:

1. Artificial insemination.
2. Excess weight increases the concentration of all hormones, while lack of weight decreases it.
3. During multiple pregnancy.
4. For diabetes mellitus.
5. Even stress and fear of the procedure can affect the result, so you need to carry out the procedure in a calm state.

The doctor will explain to you all the normal indicators and tell you who to contact if something is wrong

What is risk and how is it calculated?

The risk of developing pathology is calculated for each woman individually, because this is influenced by many parameters - age, bad habits, weight, etc. All data about the woman, as well as the screening results, are entered into a computer program that calculates the risk.

What should I do if I am at high risk?

If a child is at risk of developing Down syndrome, there is no need to panic. You should consult a geneticist, he will look into the situation in more detail.

How to confirm or refute screening results?

You have the right to be screened again if you think the previous results are not accurate. But you will have to undergo examination in another clinic and only if the pregnancy is not more than 13 weeks.

The doctor says I need to have an abortion. What to do?

No one has the right to force you to terminate a pregnancy if you are at risk of developing Down syndrome. Tell your doctor that you would like to see a genetic counselor. He will send you for one of the procedures - chorionic villus biopsy (in case of pregnancy at a period of 10 to 13 weeks), or for amniocentesis (16-17 weeks).

Second screening during pregnancy, when to do it and what is included in the study

As with the first screening, during the second you will also need to undergo an ultrasound and donate blood. It occurs from 16 to 20 weeks of pregnancy.

Even if the screening result is bad, don’t get upset ahead of time - you can go through the procedure again

Third screening during pregnancy

If the previous two screenings did not show any abnormalities, then the pregnant woman will only have to undergo ultrasound diagnostics, and there will be no need to donate blood (but they usually insist on this).

Additionally, you must undergo the following procedures:

• Dopplerography – evaluates the blood vessels of the placenta;
• cardiotocography – determines heart rate;
• blood biochemistry.

Timing of the third screening during pregnancy

The doctor makes the decision; most often he prescribes an examination at the 32nd week, but it can be done from the 28th to the 34th.

Where to take the study

Both private and government clinics offer this service. However, it will be paid both in a public institution and in a private one.

EVERYTHING IS UNDER CONTROL

There are a number of studies, thanks to which the risk of having a child with pathologies such as Down syndrome, Edwards syndrome and gross malformations is detected at the earliest stages of pregnancy. We are talking about prenatal screening.

What is this?

Of all the expectant mothers who have been examined, a group of women is identified whose results differ significantly from the norm. This suggests that their fetus is more likely to have some pathologies or defects than others. Prenatal screening is a set of studies aimed at identifying developmental anomalies or gross malformations of the fetus.

The complex includes:

Biochemical screening is a blood test that allows you to determine the presence in the blood of specific substances (“markers”) that change in certain pathologies, such as Down syndrome, Edwards syndrome and neural tube malformations. Biochemical screening itself is only a confirmation of probability, but not a diagnosis. Therefore, additional research is being done along with it;

Ultrasound screening (ultrasound) is performed in each trimester of pregnancy and allows you to identify most anatomical defects and developmental abnormalities of the child. Prenatal screening consists of several stages, each of which is important as it provides information about the child’s development and possible problems.

Risk factors for the development of pathology in the unborn child:

– woman’s age over 35 years;

– the presence of at least two spontaneous abortions in the early stages of pregnancy;

– use of a number of pharmacological drugs before conception or in early pregnancy;

– bacterial and viral infections suffered by the expectant mother;

– the presence in the family of a child with genetically confirmed Down syndrome, other chromosomal diseases, congenital malformations;

– familial carriage of chromosomal abnormalities;

– hereditary diseases in close relatives;

– radiation exposure or other harmful effects on one of the spouses before conception.

First trimester examinations

"Double Test"

Carry out from the 10th to 14th weeks of pregnancy (the optimal time is from the 11th to 13th weeks)

Combined screening

– Ultrasound examination, during which the main parameters are measured: the coccygeal-parietal size (CTR) and the thickness of the nuchal space (TVP). A TVP of more than 3 mm may indicate possible fetal developmental disorders. Additional research is required to confirm (or refute) this. Screening is informative only when the fetal CTE is equal to or more than 45.85 mm.

– Biochemical screening:

– blood test for hCG

– RARR-A (PAPP-A).

It is necessary to begin the examination with ultrasound screening, since the obtained indicators can identify factors that make the results of biochemistry uninformative, for example, more accurate timing of pregnancy (not corresponding to the period of 11-13 weeks), multiple pregnancies, problems with the development of pregnancy (for example, termination) . The data obtained from the ultrasound will be used to calculate risks in both the first and second trimester of pregnancy.

If the results of the ultrasound correspond to the required timing, then you can do biochemical screening (donate blood). The optimal time frame for this is the same as for ultrasound - 11-13 weeks. It is important to meet this time. The gap between ultrasound screening and biochemistry should be a maximum of 3 days.

What does biochemical screening examine?

– Free subunit of human chorionic hormone (hCG)

– PAPP-A – pregnancy-associated plasma protein A.

The hCG hormone is produced by the cells of the embryonic membrane (chorion). It is thanks to the hCG analysis that pregnancy can be determined already on the 6-10th day after fertilization. The level of this hormone increases in the first trimester and reaches its maximum by the 10-12th week. Then it gradually decreases and remains constant during the second half of pregnancy.

The hCG hormone is made up of two units (alpha and beta). Of these, beta is a unique one, which is used in diagnostics.

If beta-hCG levels are elevated, this may indicate:

– multiple births (the hCG rate increases in proportion to the number of fetuses);

– Down syndrome and some other pathologies;

– toxicosis;

– diabetes mellitus in the expectant mother;

– incorrectly determined gestational age.

If the beta-hCG level is low, this may indicate:

– presence of ectopic pregnancy;

– non-developing pregnancy or threat of spontaneous abortion;

– delayed development of the unborn baby;

– placental insufficiency;

– fetal death (in the second and third trimester of pregnancy).

NORMAL HCG IN BLOOD SERUM

HCG level during pregnancy HCG norm, honey/ml

1st - 2nd week 25 - 300

2-3rd week 1500-5000

3-4th week 10000-30000

4th - 5th week 20000 - 100000

5-6th week 50000-200000

6-7th week 50000-200000

7-8th week 20000-200000

8-9th week 20000-100000

9-10th week 20000-95000

11-12th week 20000-90000

13-14th week 15000-60000

15-25th week 10000-35000

26-37th week 10000-60000

RARR-A (PAPP-A)– a protein that modulates the immune response of the maternal body and is one of the factors ensuring the functioning of the placenta. The analysis is carried out in the first trimester of pregnancy.

A decrease in PAPP-A levels indicates the likelihood of:

– chromosomal abnormalities of the fetus;

– Down syndrome, Edwards syndrome, Corneille de Lange syndrome;

– threats of miscarriage or termination of pregnancy.

NORMAL PAPP-A IN BLOOD SERUM

Week of pregnancy Norm PAPP-A, honey/ml

8-9th week 0.17-1.54

9-10th week 0.32-2.42

10-11th week 0.46-3.73

11-12th week 0.7- 4.76

12-13th week 1.03-6.01

13-14th week 1.47-8.54

MoM – To calculate risk indicators, it is not the specific data obtained that is used, but the so-called MoM. This is a coefficient showing the degree of deviation of the value of a particular prenatal screening indicator from the average value (median) for the gestational age.

It is calculated using the following formula:

MoM = serum value divided by the median value for a given period of pregnancy

A value of the indicator close to one is considered the norm.

There are a number of factors that can affect the value of the obtained indicators:

– pregnant woman’s weight

– taking medications;

– a history of diabetes mellitus in the expectant mother;

– pregnancy as a result of IVF.

Therefore, when calculating risks, doctors use the MoM value, adjusted taking into account all the features and factors.

The normal MoM level ranges from 0.5 to 2.5. And in the case of multiple pregnancy, up to 3.5 MoM.

Depending on the results obtained, it will be clear whether the expectant mother is at risk for chromosomal pathologies or not. If this is the case, your doctor will recommend further testing.

Do not worry in advance if you have been prescribed second trimester screening; it is recommended for all pregnant women, regardless of the results of the first stage of the examination. God protects those who are careful!

Second trimester examinations

"Triple Test"

Carry out from the 16th to 20th weeks of pregnancy (the optimal time is from the 16th to 18th weeks)

Combined screening

– Ultrasound examination(using data obtained in the first trimester).

– Biochemical screening:

– blood test for AFP;

– free estriol;

– human chorionic gonadotropin (hCG)

The second screening is also aimed at identifying the degree of risk of having a child with Down syndrome, Edwards syndrome, neural tube defect and other anomalies. During the second screening, placental hormone and fetal liver hormone are examined, which also provide the necessary information about the development of the child.

Alpha fetoprotein(AFP) is a protein present in the blood of a child in the early stages of embryonic development. Produced in the liver and gastrointestinal tract of the fetus. The action of alpha-fetoprotein is aimed at protecting the fetus from the maternal immune system.

An increase in AFP level indicates the likelihood of the existence of:

– malformation of the neural tube of the fetus (anencephaly, spina bifida);

– Meckel’s syndrome (sign: occipital cranial hernia);

– esophageal atresia (pathology of intrauterine development, when the fetus’s esophagus ends blindly without reaching the stomach (the child cannot take food through the mouth);

– umbilical hernia;

– nonunion of the anterior abdominal wall of the fetus;

– fetal liver necrosis due to viral infection.

A decrease in AFP levels suggests:

– Down syndrome - trisomy 21 (term after);

– Edwards syndrome – trisomy 18;

– incorrectly determined gestational age (longer than needed for the study);

- death of the fetus.

AFP NORMAL IN BLOOD SERUM

Week of pregnancy AFP level, U/ml

13- 15th 15- 60

15- 19th 15- 95

20- 24th 27- 125

25- 27th 52- 140

28- 30th 67- 150

31- 32nd 100- 250

Free estriol- This hormone is produced first by the placenta and subsequently by the fetal liver. During normal pregnancy, the level of this hormone constantly increases.

An increase in estriol levels may indicate:

– multiple pregnancy;

– large fruit;

– liver and kidney diseases in the expectant mother.

A decrease in estriol levels may indicate:

– fetoplacental insufficiency;

– Down syndrome;

– fetal anencephaly;

– threat of premature birth;

– fetal adrenal hypoplasia;

– intrauterine infection.

NORMAL ESTRIOL IN BLOOD SERUM

Week of pregnancy Norm of free estriol

6-7th week 0.6-2.5

8-9th week 0.8-3.5

10-12th week 2.3-8.5

13-14th week 5.7-15.0

15-16th week 5.4-21.0

17-18th week 6.6-25.0

19-20th week 7.5-28.0

21-22nd week 12.0- 41.0

23-24th week 18.2-51.0

25-26th week 20.0- 60.0

27-28th week 21.0- 63.5

29-30th week 20.0- 68.0

31-32nd week 19.5-70.0

33-34th week 23.0- 81.0

35-36th week 25.0- 101.0

37-38th week 30.0- 112.0

39-40th week 35.0- 111.0

Ultrasound screening of the third trimester

Carry out from the 30th to 34th weeks of pregnancy (the optimal time is from the 32nd to 33rd weeks)

During an ultrasound, the condition and location of the placenta is studied, the amount of amniotic fluid and the location of the fetus in the uterus are determined.

According to indications, the doctor may prescribe additional studies - Doppler ultrasound and cardiotocography.

Doppler- this study is done starting from the 24th week of pregnancy, but most often doctors prescribe it after the 30th week.

Indications for:

– fetoplacental insufficiency;

– insufficient increase in the height of the uterine fundus;

– umbilical cord entanglement;

– gestosis, etc.

Doppler- This is an ultrasound method that provides information about the blood supply to the fetus. The speed of blood flow in the vessels of the uterus, umbilical cord, middle cerebral artery and fetal aorta is examined and compared with normal values ​​for a given period. Based on the results, conclusions are drawn about whether the blood supply to the fetus is normal and whether there is a lack of oxygen and nutrients. If necessary, medications are prescribed to improve blood supply to the placenta.

Cardiotocography (CTG)- a method for recording the fetal heartbeat and its changes in response to uterine contractions. It is recommended to start from the 32nd week of pregnancy. This method has no contraindications.

CTG is performed using an ultrasound sensor, which is attached to the pregnant woman’s abdomen (usually external, so-called indirect CTG, is used). The duration of CTG (from 40 to 60 minutes) depends on the phases of activity and rest of the fetus. CTG can be used to monitor the condition of the baby both during pregnancy and during the birth itself.

Indications for CTG:

– diabetes mellitus in the expectant mother;

– pregnancy with a negative Rh factor;

– detection of antiphospholipid antibodies during pregnancy;

– fetal growth retardation.

Only your decision

The doctor will refer you for screening and (if necessary) recommend further examination, but this should not influence the woman’s decision in any way. Many expectant mothers initially refuse screening studies, citing the fact that they will give birth in any case, regardless of the results of the study. If you are one of them and do not want to undergo screening, then it is your right and no one can force you.

The role of the doctor is to explain why such screenings are carried out, what diagnoses can be made as a result of the studies, and in the case of using invasive diagnostic methods (chorionic villus biopsy, amniocentesis, cordocentesis) to talk about the possible risks. After all, the risk of miscarriage after such examinations is about 2%. The doctor should also warn you about this.

Unfortunately, doctors do not always have enough time to explain the screening results in detail.

One of the most exciting moments for a woman during the period of bearing a child is screening for congenital pathologies of the fetus. They are carried out for all pregnant women, but not every expectant mother is told and explained in detail what kind of research this is and what it is based on.

In this regard, screenings are surrounded by a lot of prejudices; some women even refuse to undergo the procedures so as not to “waste their nerves.” We will talk about what this diagnosis is in this article.

What is it

Screening is sifting, selecting, sorting. This is the meaning of this English word, and it fully reflects the essence of diagnosis. Prenatal screening is a set of studies that allows calculate the risks of genetic pathologies.

It is important to understand that no one can say based on screening that a woman is carrying a sick child; screening results do not report this.

They only show how high the risk of giving birth to a given woman, given her age, medical history, bad habits, etc., is of a child with genetic abnormalities.

Prenatal screening during pregnancy was introduced at the national level and became mandatory more than two decades ago. During this time, it was possible to significantly reduce the number of children born with gross malformations, and prenatal diagnostics played a significant role in this.

The timing of these studies gives the woman the opportunity to terminate the pregnancy if an unfavorable prognosis is confirmed, or to leave and give birth to a child with a pathology, but to do this completely consciously.

It is not very reasonable to be afraid of screening or refuse to undergo it. After all, the results of this simple and painless study do not oblige you to anything.

If they are within the normal range, this only confirms that the child is doing well and the mother can be calm.

If a woman, according to the test results, falls into a risk group, this does not mean that her baby is sick, but it may be the basis for additional research, which in turn can show with 100% probability the presence or absence of a congenital pathology.

Screening is carried out free of charge, in any antenatal clinic, at certain stages of pregnancy. Recently, when pregnancy after 30 or 35 years is not considered an out of the ordinary phenomenon, such research is of particular importance, because with age, and this is no secret, the age-related risks of giving birth to a baby with anomalies increase.

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What risks are calculated?

Of course, no medical technique can foresee all possible pathologies that a child may have. Prenatal screenings are no exception. Studies only calculate the likelihood of a child having one of the following pathologies.

Down syndrome

The syndrome has a number of characteristic features that the child is endowed with - a flattened face, shortened skull, flat back of the head, shorter limbs, wide and short neck.

In 40% of cases, such children are born with congenital heart defects, in 30% - with strabismus. Such children are called “sunny” because they are never aggressive, they are kind and very affectionate.

The pathology is not at all as rare as is commonly thought.

Before the introduction of screening, it occurred in one in 700 newborns. After screening became widespread, and women were given the opportunity to decide whether to keep a child with this syndrome, the number of “sunny” babies decreased - now there are more than 1,200 healthy children for one such newborn.

Genetics have proven a direct connection between the mother’s age and the likelihood of Down syndrome in the child:

• a 23-year-old girl can have such a baby with a probability of 1:1563;
• a woman aged 28-29 years old has a 1:1000 chance of giving birth to a “sunny” child;
• if the mother is over 35 years old, but has not yet turned 39 years old, then the risk is already 1: 214;
• for a pregnant woman aged 45, this risk, alas, is 1:19. That is, out of 19 women at this age, one gives birth to a child with Down syndrome.

Edwards syndrome

A severe birth defect associated with trisomy 18 is less common than Down syndrome. On average, one in 3,000 children could theoretically be born with this anomaly.

In late-birthers (after 45 years), this risk is approximately 0.6-0.7%. More often, the pathology occurs in female fetuses. The risks of having such a baby are higher for women with diabetes.

Such babies are born at term, but with a low (about 2 kg) weight. Typically, children with this syndrome have changes in their skull and facial structure. They have a very small lower jaw, small mouth, narrow small eyes, deformed ears - the earlobe and tragus may be missing.

The auditory canal is also not always present, but even if it is present, it is greatly narrowed. Almost all children have a rocking-type foot structure anomaly; more than 60% have congenital heart defects. All children have a cerebellar anomaly, severe mental retardation, and a tendency to seizures.

These babies don't live long - more than half do not live to see 3 months. Only 5-6% of children can survive to one year; the rare few who survive beyond one year suffer from severe uncorrectable mental retardation.

Anencephaly

These are neural tube defects that can occur under the influence of unfavorable factors in the very early stages of pregnancy (between 3 and 4 weeks). As a result, the fetus may have underdeveloped or completely absent cerebral hemispheres, and there may be no cranial vaults.

The mortality rate from this defect is 100%, half of the children die in utero, the second half may be born, but only six of these babies out of ten manage to live for at least a couple of hours. And only a few manage to live for about a week.

This pathology is more common in multiple pregnancies, when one of the twins develops at the expense of the other. Girls are most often affected by anomalies.

The defect occurs on average in one case per 10 thousand births.

Cornelia de Lange syndrome

Such children have a shortened skull, distorted facial features, deformed ears, problems with vision and hearing, short limbs, and often missing fingers.

In most cases, babies also have malformations of internal organs - heart, kidneys, genitals. In 80% of cases, children are imbeciles; they are not even capable of simple mental activity; they often mutilate themselves because They do not control motor activity at all.

Smith-Lemli-Opitz syndrome

This disease is associated with a congenital deficiency of the enzyme 7-dehydrocholesterol reductase, which ensures the formation of cholesterol, which is necessary for all living cells in the body.

If the form is mild, symptoms may be limited to minor mental and physical impairments; with a severe form, complex defects and profound mental retardation are possible.

Most often, such children are born with microcephaly, autism, defects of the heart, lungs, kidneys, digestive organs, hearing and vision impairments, severe immunodeficiency, and bone deformities.

Every thirtieth adult on the planet is a carrier of this disease, but the “defective” DHCR7 gene is not always passed on to offspring; only one out of 20 thousand babies can be born with this syndrome.

However, the alarming number of carriers forced doctors to include this syndrome in the determination of markers during prenatal screenings.

Patau syndrome

Children are born with low birth weight (from 2 to 2.5 kg), they have a decrease in brain size, multiple pathologies of the central nervous system, anomalies in the development of the eyes, ears, face, clefts, cyclopia (one eye in the middle of the forehead).

Almost all children have heart defects, several additional spleens, and a congenital hernia with prolapse of most internal organs into the abdominal wall.

Nine out of ten babies with Patau syndrome die before they reach the age of one. About 2% of survivors may live to be 5-7 years old. They suffer from deep idiocy, are not aware of what is happening, and are incapable of basic mental actions.

Nonmolar triploidy

In combination with maternal genetics, the child does not have 46 chromosomes, but 69 or another number. Such children usually die in utero. Newborns die within a few hours or days, since multiple defects, external and internal, are incompatible with life.

This is not a hereditary disease, it occurs randomly. And during the next pregnancy, the same parents have minimal chances of repeating the negative experience. Prenatal screening also allows one to predict the possible risks of such a pathology.

All of the above pathologies, if their risk is high based on screening results and if they are confirmed as a result of an additional examination, which is prescribed because a woman is at risk, are grounds for termination of pregnancy for medical reasons at any stage.

No one will be forced to have an abortion or artificial birth, the decision to terminate remains with the pregnant woman.

Diagnostic methods

Prenatal screening methods are simple. They include:

• ultrasound examination, which, based on some characteristic markers, allows us to judge the possible presence of pathology;
• a biochemical test of blood from a vein, which reveals the concentrations of certain substances and hormones, certain values ​​of which are characteristic of certain congenital anomalies.

For whom is screening required?

For all pregnant women registered, screening tests are planned and desirable. But no one can oblige a woman to donate blood from a vein and do an ultrasound scan as part of prenatal diagnosis - this is a voluntary matter.

Therefore, every woman should think carefully, first of all, about the consequences of refusing such a simple and safe procedure.

• to expectant mothers who wanted to give birth to a child after 35 years (which child it is does not matter);
• pregnant women who have already given birth to children with congenital defects, including chromosomal abnormalities, have had cases of intrauterine fetal death due to genetic disorders in the baby;
• pregnant women who have previously had two or more miscarriages in a row;

• women who took medications, medications that should not be taken during pregnancy, in the early stages of fetal development (up to 13 weeks). Such drugs include hormonal drugs, antibiotics, some psychostimulants and other medications;
• women who conceived a baby as a result of incest (relations with a close blood relative - father, brother, son, etc.);
• expectant mothers who were exposed to radioactive radiation shortly before conception, as well as those whose sexual partners were exposed to such radiation;
• pregnant women who have relatives with genetic disorders in their family, as well as if such relatives are on the side of the future father of the child;
• expectant mothers who are carrying a child whose paternity has not been established, for example, conceived through IVF using donor sperm.

Description of the study - how the screening works

Prenatal screening cannot be called an accurate study, because it reveals only the likelihood of pathology, but not its presence. Therefore, a woman should know that the markers that laboratory assistants and the computer program that calculates the probability will rely on can be found in her blood not only because of pathologies in the child.

Thus, the concentration of some hormones turns out to be increased or decreased as a result of the simplest cold, ARVI, food poisoning, which the pregnant woman suffered on the eve of the study.

Performance may be affected lack of sleep, smoking, severe stress. If such facts occur, the woman must warn her doctor about this in consultation before she receives a referral for screening.

It is advisable to carry out each of the screenings in one day, that is, both blood from a vein for biochemical testing and a visit to the ultrasound diagnostic room should take place with a minimal time difference.

The results will be more accurate if the woman goes for an ultrasound immediately after donating blood for analysis. The results complement each other; ultrasound and blood test data are not considered separately.

First screening and interpretation of its results

This screening is also called 1st trimester screening. The optimal time frame for its implementation is 11-13 weeks.

In a number of antenatal clinics, the timing may vary slightly. Thus, it is allowed to take the test at 10 full weeks, at 11 weeks, and also at 13 full weeks before the obstetric period of 13 weeks and 6 days.

Screening begins with the woman being weighed, her height measured, and all diagnostically important information needed to calculate risks entered into a special form. The more such information is indicated, the higher the accuracy of the study.

The end result is still produced by a computer program, devoid of feelings and emotions, unbiased, and therefore the human factor is important here only at the preparatory stage - collecting and processing information.

The following are considered important for diagnosis: the age of the parents, especially the mother, her weight, the presence of chronic diseases (diabetes, heart pathologies, kidneys), hereditary diseases, the number of pregnancies, births, miscarriages and abortions, bad habits (smoking, drinking alcohol or drugs), the presence of fathers of relatives with hereditary diseases, genetic pathologies.

The first screening is considered the most important of the three. It gives the most complete picture of the baby’s health and development.

In the ultrasound room, the woman is waiting for the most ordinary ultrasound, which she has probably already had done to confirm the fact of the pregnancy.

As part of a screening study, ultrasound is used to look at:

• The body of the baby - are all the limbs present, are they positioned correctly? If desired, the diagnostician can even count the baby’s fingers.
• The presence of internal organs - heart, kidneys.
• OG - fetal head circumference. This is a diagnostically important indicator that allows us to judge the correct formation of the brain lobes.
• KTR - the distance from the coccyx to the crown. Allows you to judge the growth rate of the child, as well as clarify the gestational age accurate to the day.
• LZR - fronto-occipital size of the fetus.

• Heart rate is the baby’s heart rate; the diagnostician also notes whether the heart contractions are rhythmic.
• Dimensions and location of the placenta, place of attachment.
• The number and condition of the umbilical cord vessels (some genetic pathologies may manifest as a decrease in the number of vessels).
• TVP is the main marker that allows us to judge the likelihood of the most common pathology - Down syndrome, as well as some other developmental anomalies (Edwards syndrome, Turner syndrome, pathologies of bone structure, heart.

The nuchal translucency thickness is the distance from the skin to the muscles and ligaments at the back of the fetal neck.

TTP is measured in millimeters, and the thickening of this skin fold, which is characteristic of children with chromosomal disorders and developmental defects, is undesirable.

TVP standards for first trimester screening:

Gestational age

Collar thickness

Deviations from the average parameters can indicate not only some pathologies, but also hereditary features of appearance. Therefore, an experienced diagnostician will never scare a pregnant woman with the fact that her baby’s head is too big if he sees that the mother’s head is also rather large, and the father (who, by the way, can be taken with you to the ultrasound room) is also not that type people with small skulls.

Children grow in leaps and bounds, and a slight lag behind the norm does not mean that such a baby is not receiving enough nutrition, suffers from malnutrition or congenital diseases. Deviation from the standard values ​​indicated in the table will be assessed by the doctor individually. If necessary, the woman will be prescribed additional diagnostic procedures.

In addition to the fetometric parameters of the baby, in the ultrasound diagnostic room during mid-pregnancy screening, the woman will be told how the baby is located in space - up or down, and his internal organs will be examined, which it is very important to understand whether there are any malformations of their development:

• lateral ventricles of the brain - normally do not exceed 10-11.5 mm;
• the lungs, as well as the spine, kidneys, stomach, and bladder are indicated as “normal” or “N” if there is nothing unusual in them;
• the heart must have 4 chambers.

The diagnostician pays attention to the location of the placenta. If in the first trimester it was located low, then the chances that by the second screening the child’s place will rise are high. It is taken into account which wall of the uterus it is attached to - the anterior or posterior.

This is important so that the doctor can make a decision on which method to carry out the birth.

Sometimes the location of the placenta on the anterior uterine wall increases the likelihood of abruption; in this situation, a cesarean section may be recommended. The maturity of the placenta itself at the period in which the second study is carried out has a zero degree, and the structure of the child's place should be homogeneous.

Such a concept to IAF - amniotic fluid index, indicates the amount of water. We already know that some congenital defects are accompanied by oligohydramnios, but this index in itself cannot be a symptom of genetic diseases. Rather, it is needed to determine tactics for further management of pregnancy.

Amniotic fluid index norms:

Particular attention during the study as part of the second screening is paid to the condition and characteristics of the umbilical cord - the cord connecting the child to the placenta. Normally, it contains 3 vessels - two arteries and one vein. According to them, an exchange takes place between the child and the mother. The baby receives nutrients and blood saturated with oxygen, and metabolic products and blood containing carbon dioxide go back to the mother.

If there are only 2 vessels in the umbilical cord, this may indirectly indicate Down syndrome and some other chromosomal disorders, but it is also possible that the work of the missing vessel is compensated by the existing one, and the child is healthy. Such babies are born weaker and underweight, but they do not have genetic abnormalities.

The doctor will advise the pregnant woman not to worry about missing vessels in the umbilical cord if other ultrasound indicators are within normal limits, and a double or triple test (biochemical blood test) does not show significant abnormalities.

The blood test is most often a triple test. In a sample of the venous blood of the expectant mother, the concentration of free hCG, free estriol and AFP (alpha-fetoprotein) is determined. These substances give an idea of ​​the course of pregnancy and the possible risks of genetic pathologies in the baby.

Standards vary from laboratory to laboratory; MoM values ​​are used to summarize various data. Each of the three markers ideally lies somewhere between 0.5-2.0 MoM.

HCG level at second screening:

An increase in the level of this hormone in the second screening often indicates that the woman has gestosis, she has edema, there is protein in her urine, she has taken or is taking certain hormonal medications, for example, to maintain pregnancy.

HCG levels are elevated in women carrying twins or triplets. Sometimes an increase in the value of this substance indicates that the deadline was set incorrectly and an adjustment is required.

A chromosomal pathology such as Down syndrome can be signaled by a significant excess of the upper hCG threshold with a simultaneous significant decrease in the other two components of the triple test. Alpha-fetoprotein and the hormone estriol are pathologically low.

Free estriol level in the second screening:

A slight excess in the concentration of this female sex hormone may be associated with a multiple pregnancy or with the fact that a woman is carrying a large fetus.

A decrease in this hormone may indicate the likelihood of neural tube defects, such as Down syndrome or Turner disease, as well as Patau syndrome or Cornelia de Lange. Not every decrease in this substance is considered pathological; doctors begin to sound the alarm when the level is reduced by more than 40% of the average value.

A reduced level of estriol can sometimes indicate an inflamed Rhesus conflict, the threat of premature birth, as well as insufficient placental nutrition of the child.

The placenta can become thinner than required by standards in thin and slender women, as well as in expectant mothers who have suffered from infectious diseases during pregnancy.

A thickening of the baby's place often indicates the presence of a Rh conflict; it is typical in the third trimester for women suffering from diabetes mellitus and gestosis. The thickness of the placenta is not a marker of chromosomal pathologies.

The fetometry of children at these stages can already differ significantly from the normative values, because everyone is born with different parameters, weight, and everyone is similar to their mother and father.

A thin surgical instrument can be inserted in three ways - through the abdominal wall, through the cervical canal and through a puncture in the vaginal vault. Choosing a specific method is the task of specialists who know exactly how and where exactly the placenta is located in a particular woman.

The entire procedure is carried out under the supervision of an experienced, qualified ultrasound doctor; everything that happens in real time is monitored by an ultrasound scanner.

The danger of such studies lies in the possibility of early rupture of water and termination of pregnancy. A baby in the womb can be injured by a sharp thin instrument, and placental abruption and inflammation of the membranes may begin. The mother can also be injured; the integrity of her intestines and bladder are at risk.

Knowing this, every woman has the right to decide for herself whether to agree to invasive diagnostics or not. No one can force her to undergo the procedure.

Since 2012, a new method of research has been carried out in Russia - non-invasive prenatal DNA test. Unlike the invasive methods described above, it can be done as early as 9 weeks of pregnancy.

The essence of the method is to isolate the baby's DNA molecules from the mother's blood, since from the 8th week of pregnancy the baby has its own blood supply, and some of its red blood cells enter the mother's bloodstream.

The laboratory assistant’s task is to find these red blood cells, extract DNA from them and determine whether the child has congenital pathologies. At the same time, the technique makes it possible to determine not only the presence of gross chromosomal abnormalities, but also other gene mutations that cannot be found out by any other means. Also, the mother will be told the gender of the baby with 99.9% accuracy as early as 9 weeks of pregnancy.

Such tests, unfortunately, are not yet included in the health insurance package, and therefore are paid for. Their average cost is from 40 to 55 thousand rubles. It is offered by many private medical genetic clinics.

The downside is that you will still have to undergo an invasive test with a puncture of the amniotic sac if a non-invasive DNA test shows that there are abnormalities.

The results of such an innovative test are not yet accepted by gynecological hospitals and maternity hospitals as a basis for terminating a long-term pregnancy for medical reasons.

Preparing for screenings

The result of a screening at a antenatal clinic may turn out to be false, either positive or negative, if a woman does not take into account the negative impact of certain factors on her body, such as taking medications or severe stress. Therefore, doctors recommend carefully preparing for a simple test.

Three days before the screening It is not recommended to eat fatty, fried and spicy foods. This may distort the results of a biochemical blood test.

The diet also means avoiding chocolate, cakes, oranges, lemons and other citrus fruits, as well as smoked foods.

Blood should be donated on an empty stomach. But you can take crackers or a small chocolate bar with you to the consultation so that after donating blood you can eat it before undergoing the ultrasound procedure.

The child, under the influence of the chocolate eaten by the mother, will move more actively and will be able to “appear” to the diagnostician in all its glory. On an empty stomach does not mean that a woman should starve herself and her baby for three days. To successfully donate blood for biochemistry, it is enough not to eat for at least 6 hours before taking blood.

During the week, all stress factors should be eliminated; on the evening before the examination, the woman should take a drug that reduces the formation of gases in the intestines, so that the “bloated” intestine does not cause compression of the abdominal organs and does not affect the results of the ultrasound examination. A safe drug for expectant mothers - "Espumizan".

It is not necessary to fill the bladder; at this period (10-13 weeks) the fetus is clearly visible even without filling the bladder.

Accuracy of the study

The accuracy of second trimester screening is lower than that of the first screening, although its results raise many questions. So, sometimes it turns out that a woman who was put at high risk gives birth to a completely healthy baby, and a girl who was told that everything was “normal” becomes the mother of a baby with severe genetic pathologies and developmental anomalies.

Accurate research is considered only invasive diagnostic methods. The accuracy of screening for Down syndrome using blood tests and ultrasound is estimated by specialists to be approximately 85%. Screening detects trisomy 18 with an accuracy of 77%. However, these are official statistics; in practice, everything is much more interesting.

The number of false-positive and false-negative screenings has been increasing recently. This is not due to the fact that doctors began to work worse. It’s just that many women, hoping for the competence of paid specialists, try to undergo research at their own expense in a paid center, and there ultrasound is not always performed by specialists who have international clearance to conduct this type of research.

The number of incorrect analyzes is also growing, since even with modern equipment, living people work in laboratories.

There is always a chance that the doctor did not notice something during the ultrasound or saw something completely different from what is there, and that the laboratory technicians made a basic technical error. Therefore, sometimes data from one laboratory should be double-checked in another.

It is best to undergo a screening test at a consultation at your place of residence - doctors there are guaranteed to have not only access to this type of diagnosis, but also extensive experience in performing it.

It is important to remain calm and trust that everything will be fine with the child, without giving up the opportunity to learn as much as possible about the baby's condition. Screening provides just such an opportunity.

Biochemical screening is a test of a pregnant woman's blood to determine specific markers that help determine the likelihood of severe genetic disorders in the fetus.

From the moment of its formation, the placenta begins to produce certain substances, which then penetrate into the maternal blood. The number of these markers normally changes constantly as the fetus develops. The determination of these substances is the basis of biochemical screening: significant deviations of the results obtained from accepted norms indicate a high possibility of the presence of chromosomal abnormalities or.

information Of course, such laboratory tests cannot make a diagnosis, but they help to select a group of women at high risk of having children with pathology and offer them further in-depth examination to clarify the situation.

Biochemical screening is performed twice during the entire period of gestation: in the first trimester (10-14 weeks) and in the second trimester (16-20 weeks).

Indications for use

The need for biochemical screening in all pregnant women is still controversial. Most experts recommend this test for all patients, because no one is immune from genetic disorders. The World Health Organization (WHO) recommends at least mandatory laboratory tests for all pregnant women.

This analysis is not mandatory, and the decision to perform it is voluntary for every expectant mother, although, of course, it won’t hurt to insure yourself once again.

In addition, groups of women who have a high risk of having children with genetic pathology have been identified. Such patients should be examined twice during the entire gestation period.

At-risk groups, requiring mandatory biochemical screening:

• The woman’s age is over 30 years old during the first pregnancy and over 35 years old during the second and subsequent ones;
• 2 or more spontaneous abortions in the anamnesis;
• Self-administration of medications in the early stages that have a teratogenic effect;
• Infectious diseases suffered in the first trimester;
• Presence of relatives in the family with genetic abnormalities;
• The presence of genetic abnormalities in one or both parents;
• Previous birth in the family of a child with genetic abnormalities;
• Stillbirth or death of another child from developmental defects in the family previously;
• Marriage between close relatives;
• Radiation exposure of one or both parents before conception or in early pregnancy;
• Abnormalities detected on fetal ultrasound.

First biochemical screening

Biochemical screening of the 1st trimester is performed at 10-14 weeks, but most experts consider it more informative to conduct a study at 11-13 weeks.

The first screening is a “double test”, i.e. detect two substances in the blood: (in particular, free unit of human chorionic gonadotropin) and PAPP-A (pregnancy-associated plasma protein A).

Norms

Chorionic gonadotropin is secreted by the cells of the chorion (the membrane of the embryo), so it begins to be detected in the blood quite early (already in the first days after conception has occurred). Then its amount gradually increases, reaches a maximum at the end of the first trimester, then begins to decrease and remains at a constant level from the second half of pregnancy.

Normal hCG levels

RARR-A is a protein produced by the trophoblast throughout the entire gestation period, its amount constantly increases in proportion to the duration of pregnancy.

Normal indicators of PAPP-A

Gestation period, weeks	Normal parameters PAPP-A, honey/ml
	Minimum value	Maximum value
8-9	0.17	1.54
9-10	0.32	2.42
10-11	0.46	3.73
11-12	0.7	4.76
12-13	1.03	6.01
13-14	1.47	8.54

additionally The result of biochemical screening is assessed not only by the results obtained, but also by the MoM value, which ultimately is the determining factor. MoM is a coefficient showing the degree of deviation of the obtained indicator from the average normal indicator for a given period of pregnancy. The normal MoM ranges from 0.5 to 2.5 (for multiple pregnancies, up to 3.5 MoM).

Decoding

Explanation of biochemical screeningshould only be carried out by the attending physician. It should be borne in mind that each laboratory, depending on the reagents used, may have its own standards for indicators; therefore, using incorrect data, you can get false results.

Decoding the analysis for hCG

Deviations from the norm	Reasons
Reduced hCG levels
	Retarded embryonic development
	High risk of spontaneous miscarriage
	Edwards syndrome in the fetus
Elevated hCG levels	Multiple pregnancy
	Severe toxicosis
	Maternal diabetes mellitus
	Down syndrome in the fetus
	Severe developmental defects in the fetus (cardiovascular, nervous system, etc.)
	Taking progestin drugs (,)
	Malignant diseases (hydatidiform mole, chorionic carcinoma)

Decoding the analysis for PAPP-A

Biochemical screening in the second trimester

Biochemical screening of the 2nd trimester consists of a “triple test”: determination of AFP (alpha-fetoprotein), hCG and free estriol. The analysis is performed from 16 to 20 weeks, but the most informative examination will be at 16-18 weeks.

Triple Test Standards

AFP– a protein produced in the gastrointestinal tract and liver of the fetus from the early stages of its development.

Normal AFP values

Normal hCG levels

Free estriol is a hormone produced initially only by the placenta, and then by the child’s liver. During normal pregnancy, the amount of free estriol constantly increases.

Normal levels of free estriol during pregnancy

Decoding

2 biochemical screening should also be interpreted only by the attending physician, taking into account the standards of the given laboratory.

Deciphering the AFP analysis

Explanation of the analysis for free estriol