BDP screening what. Biochemical screening, what is this analysis? Determine the health of the fetus

Expectant mothers may be overcome by various fears about the health of their child. Biochemical screening of the first trimester, which is completely safe for mother and baby, was developed especially for the establishment of diseases in early pregnancy. In combination with other research methods, it gives high accuracy of results.

What is first trimester biochemical screening

Biochemical screening of the first trimester is a set of procedures aimed at analyzing specific blood proteins of a pregnant woman. Based on the results of the analysis, experts conclude that there are no or presence of fetal chromosomal abnormalities.

This test is completely safe, unlike invasive tests that can lead to miscarriage.

First trimester screening is done from 11 to 13 weeks of pregnancy.

Biochemical screening is not performed separately from other first trimester tests, as its results will not be sufficient to assess the health of the fetus and cannot be correlated with the timing of pregnancy.

Video: prenatal screening of the first trimester of pregnancy

The need for research

However, there are special indications for the examination:

the woman's age is more than 35 years;
risk of miscarriage;
spontaneous abortions in the past;
frozen pregnancy in history;
infectious diseases during pregnancy;
children born with developmental anomalies;
established chromosomal abnormalities in past pregnancies;
taking illegal drugs;
hereditary diseases in father and mother;
alcoholism;
addiction;
smoking;
professional hazards;
close relationship between the father and mother of the child;
radiation exposure of the father and mother.

What pathologies can be identified

Biochemical screening is aimed at identifying chromosomal abnormalities in the fetus - Down syndrome and Edwards syndrome.

Down syndrome

Children with Down syndrome are called "sunny" for their kind nature, smiling and love for others.

Chromosomal anomaly, represented by an increased number of the 21st chromosome or its sections. Another name for the syndrome is trisomy on chromosome 21. On average, it occurs 1 time in 700 cases of pregnancy and 1 time in 1100 cases of childbirth, since many pregnant women resort to abortion after learning about the presence of this disease in the fetus.

Children born with this syndrome have distinctive external features: a flattened face, shortened limbs and skull, a special shape of the eyes, a transverse fold in the palm. As a rule, there are deviations in the development of the cardiovascular system, and reduced immunity leads to frequent infectious diseases.

The degree of mental retardation depends on the level of abnormalities in the body and the quality of the child's education.

Edwards syndrome

Chromosomal abnormality due to trisomy 18. Most often, girls suffer from Edwards syndrome. The risk of having a child with this condition increases with the age of the mother.

At birth, children have low weight and multiple deviations in both mental and physical development: anomalies of the skull and bones, heart defects, decreased muscle tone.

About 60% of babies born with Edwards syndrome die before the age of three months, up to 10% of children with pathology live up to a year, and the rest live with severe medical disabilities and mental retardation.

Preparation for taking blood for analysis

Preparation for the analysis should be carried out a few days before it. Eliminate sweets, nuts, seafood, fatty, spicy and smoked foods, citrus fruits from the diet. Remember that pregnant women should not drink alcohol, especially before the test.

The analysis itself is carried out on an empty stomach in the morning, five hours before it, you can drink a glass of non-carbonated drinking water.

Factors affecting the results of the analysis

There are special cases in which it is very difficult, and often even impossible, to give a reliable assessment of the results of the analysis:

with multiple pregnancies, it is very difficult to calculate the risks of having a handicapped child, since the results must be distributed among several children;
with in vitro fertilization, the values of β-hCG will be higher, and PAPP-A will be lower than average;
overweight mother is a common cause of errors in tests, as the level of many hormones changes in a woman and the indicators will be increased;
low maternal weight leads to underestimation;
diabetes mellitus gives false test results;
mother's smoking or alcoholism;
colds during the test;
risk of miscarriage.

Normal β-hCG levels by week of pregnancy

β-hCG, a glycoprotein produced by the placental trophoblast, is very important during the first trimester of pregnancy, its level increases in the first months and then gradually decreases and remains approximately at the same level in the second half of pregnancy. According to its content in the mother's blood, we can talk about the presence of various disorders in the development of the fetus or the health of the woman.

With an increased level of β-hCG, there may be:

Down syndrome in the fetus;
multiple pregnancy;
diabetes mellitus or maternal trophoblastic disease.

Decreased levels of β-hCG may indicate:

Edwards syndrome;
placental insufficiency;
the threat of miscarriage;
ectopic pregnancy.

The result of the analysis for β-hCG is not sufficient to make a diagnosis, it is necessary to study all the data in the aggregate.

RAPP-A norms

PAPP-A is a protein produced by the placenta and is responsible for its development and functionality, as well as for the immune response during pregnancy. Synthesis occurs throughout pregnancy and increases in proportion to its duration.

If the level of PAPP-A is lowered, then this may indicate:

down syndrome;
Edwards syndrome;
Cornelia de Lange syndrome;
the threat of miscarriage;
placental insufficiency;
maternal liver disease.

A strongly elevated level of PAPP-A is a sign of a threatened miscarriage or infection.

Calculation of the MOM coefficient and its interpretation

After the ultrasound and biochemical screening of the first trimester, the doctor will calculate the MoM coefficient. It shows the level of deviation of the results from the average normal value.

Important: it is necessary to calculate the risk and decipher it in the same medical institution where you took the tests, since each laboratory may have its own units of measurement, coefficients, etc.

Normal values of the MoM coefficient are 0.5–2.5, with multiple pregnancies up to 3.5.

The most reliable results are processed by a special computer program. It takes into account the data obtained from ultrasound, biochemical screening, the age of the mother, her weight, diseases, and even nationality. The result is an individual risk of chromosomal abnormalities for each patient in the form of a fraction (1:20, 1:100, 1:2000, etc.). If the risk is 1:400, then this means that in 400 pregnancies with similar data, 1 sick child is born. A risk of less than 1:380 is considered high.

Evaluating the result, the laboratory issues the following conclusion:

The test is positive. The risk of having a child with developmental disabilities is very high. Additional tests are prescribed (3D ultrasound, amniocentesis, chorionic villus sampling, etc.)
The test is negative. The risk of having a child with abnormalities is very low, and additional tests are not necessary.

When evaluating all the data of the obtained analyzes and the woman's anamnesis with a computer program, the accuracy of the result reaches 85%.

If the test turned out to be positive, do not panic and immediately have an abortion. Seek advice from a geneticist and undergo a series of additional studies that will accurately determine the presence or absence of a disease in your child. You can have a repeat biochemical screening at a different lab if your pregnancy is less than 13 weeks and 6 days old. Please note that the value of one of the analyzes does not yet indicate any deviation, you must study all the materials received together with the doctor and only after that draw conclusions.

Additional tests

In addition to PAPP-A and β-hCG, there are other hormones that are analyzed to assess the risk of developing pathologies.

AFP or alpha-fetoprotein is a protein produced by the corpus luteum of the ovaries, and from the fifth week by the liver of the embryo. The value of AFP in the first trimester should not exceed 15 units / ml.

With elevated AFP values in a child, they can detect:

Down syndrome;
violations of the development of the central nervous system;
liver necrosis or umbilical hernia.

A low level of the hormone may indicate a missed pregnancy.

Free estradiol is a very important hormone for the proper course of pregnancy. The hormone level in the first trimester is 1030-2210 pg / ml.

Deviations from the norm may indicate:

placental insufficiency;
the threat of miscarriage and premature birth;
liver disease in the expectant mother.

Do not neglect the opportunity to take a blood test for biochemical screening, perhaps for the full bearing of a healthy child, you will need medication or any other correction during pregnancy. Choose a qualified specialist, he will be able to correctly decipher the results and give an accurate assessment of the data received.

Every expectant mother from the moment of conception of a child begins to tune in to a lot of tests, analyzes and medical consultations. As frightening as all this may be for pregnant women, without such studies it is not possible to reveal the likely serious risks associated with the health of the fetus. Throughout the entire period, it is necessary to adhere to the entire prevention program, which is prescribed by the attending gynecologist.

It is important not to neglect the recommended analyzes. Biochemical screening is considered one of the most mandatory tests. Despite the unattractive name, this analysis is very useful for building a picture of the health of the unborn child.

What it is

Biochemical blood screening is a rather narrow-profile analysis. Refers to the initial and additional categories of tests. Detects signs of diseases such as hepatitis B and rubella. In the extended version, the analysis allows you to determine the presence of syphilis and HIV infection in the blood.

Nevertheless, the main function of screening is to identify the predisposition of the fetus to pathologies. Also, the results of the analysis clearly demonstrate how certain diseases will develop in the embryo in the future. In this regard, the attending physician builds a phased program for the treatment or prevention of pathologies. Biochemical screening allows you to determine the Rh factor and blood type. These characteristics will be extremely useful in the future if the mother needs proper treatment. For the appointment of serious hormonal drugs, it is important to know the Rh factor of the pregnant woman and her offspring.

The procedure includes an examination of the chorion, from which the placenta will subsequently form, an assessment of the tone of the uterus and the condition of the ovaries. During the study, the symmetry of the hemispheres and the degree of development of the fetal brain, the presence and symmetry of the arms and legs, the correct position of the heart and stomach, the length of the femur, shoulder, forearm and lower leg bones are measured.

When calculating the risks of developing a genetic pathology of the fetus, the following are taken into account, depending on the week of pregnancy:

The thickness of the collar space (TVP), that is, the distance from the inner surface of the skin of the neck to the outer surface of the soft tissues covering the cervical spine. Normally, 0.8 - 2.8 mm, the more the size of the collar zone exceeds the norm, the higher the risk of a chromosomal abnormality in the fetus. More precisely, this risk can be calculated in the aggregate of all screening data of the first trimester of pregnancy.
The presence of a nasal bone; for a period of 12-13 weeks of pregnancy, the length of the nasal bone is normally at least 3 mm.
Correspondence of the anthropological parameters of the fetus to the gestational age:

biparietal head diameter (BDP), the distance from the forehead to the back of the head, at 13 weeks - an average of 26 mm;
coccyx-parietal size (KTR) - length from the tailbone to the crown, normally from 45 to 84 mm;
heart rate (HR); 147-171 bpm at 13 weeks.

NOTE. It is impossible to diagnose Down syndrome and other genetic pathologies based only on ultrasound data. It is necessary to evaluate the results obtained in conjunction with indicators of chromosomal abnormalities obtained from a blood test.

Biochemistry of blood

Blood for biochemical analysis is taken from a vein, early in the morning, on an empty stomach. It checks the level of two important indicators of genetic pathologies that make up human chorionic gonadotropin () - a hormone that is present only in the body of a pregnant woman:

free beta (β) hCG. Responsible for the support and development of pregnancy, it is secreted by the cells of the shell of the embryo (chorion).
If the indicator is less than normal, we can talk about the threat of miscarriage, placental insufficiency, ectopic pregnancy, the likelihood of Edwards syndrome in the fetus. Exceeding the level of free β-hCG can be not only due to chromosomal mutations, including Down's syndrome, but also in multiple pregnancies or maternal diabetes mellitus.
PAPP-A protein (plasma protein). It is synthesized by plasma, ensures the development and functioning of the placenta, and is responsible for immunity.
The output of the indicator beyond the norm may indicate possible genetic pathologies of the fetus, as well as increased uterine tone, regression of pregnancy, and the threat of miscarriage.

Increased BDP may be a symptom of the presence of a brain tumor or hernia, the development of hydrocephalus.

In the first case, the pregnancy is interrupted, with hydrocephalus, antibiotic treatment is prescribed.

A greatly underestimated BDP of the head of the embryo also does not bode well, as it is a symptom of underdevelopment of the brain. As a rule, such a pregnancy is terminated.

It includes another important indicator - the size of the nasal bone. This marker, like TVP, may be a sign of the development of Down syndrome in the embryo.

Despite the fact that prenatal examination at an early stage (10-11 weeks) does not allow us to estimate the size of the nasal bone, during this period it is still visualized on the screen.

Already at 12-13 weeks, prenatal ultrasound should show that the nasal bone is normal, a size of at least 3 mm is considered the norm.

Prenatal first biochemical screening involves testing the levels of two hormones, which is why it is also called the "double test".

Biochemical screening helps to identify and determine the level of hCG in the blood of the expectant mother, as well as to examine the blood plasma for the presence and amount of protein (PAPP).

Both of these substances are in the blood only in women who are carrying a child.

As soon as the prenatal first biochemical screening has been carried out, the decoding of the finished results is carried out taking into account the established standards:

the level of hCG of the first trimester should be 0.5 - 2 MoM;
the level of PAPP of the first trimester should be from 9 to 13 weeks - 0.17 - 6.01 mU / ml.

A strong deviation from the established standards of the prenatal test may be a symptom of the development of Down or Edwards syndromes, but only a doctor can judge the presence of such pathologies, but taking into account additional examinations.

Prenatal biochemical test of the second trimester

If the prenatal test of the 1st trimester can detect up to 95% of cases of chromosomal abnormalities, then a timely prenatal screening test of the second trimester is no less informative in this regard.

But the main purpose of the second prenatal examination is to detect neural tube defects and other fetal malformations, as well as to carry out calculations that subsequently allow us to identify the risk of congenital hereditary or chromosomal diseases, among them:

Patau syndrome;
hereditary diseases Shershevsky-Turner syndrome and Smith-Opitz syndrome;
polyploidy.

As a rule, after the mother has passed the first comprehensive examination, second trimester screening is prescribed either at the request of future parents, or as directed by a doctor in specific cases.

Screening is carried out for the 2nd trimester for a period of 16-20 weeks. Assessment of biochemical parameters of the blood of the expectant mother is carried out at 16 - 18 obstetric weeks.

Before donating blood for analysis, a pregnant woman should have with her the ultrasound results of the first trimester indicating the exact gestational age.

Before donating blood for a biochemical analysis, the doctor directing the pregnant woman for examination fills out the 2nd screening questionnaire together with her, where he indicates the results of ultrasound, the term, the parameters of TVP and CRT.

All this is the data of an ultrasound examination of the first trimester, since the second ultrasound at 16-18 weeks is too early to do, it is carried out at 20-21 weeks.

The pregnant woman takes the questionnaire filled out in accordance with all the rules to the laboratory, where they take blood for hCG, AFP and NES.

The main thing is to take tests on an empty stomach, and on the eve of the procedure do not eat too salty, spicy and fatty foods, which can distort the results.

When the results of the biochemical screening of the second trimester are ready, the doctor examines the information received and, comparing it with the established norms of the triple test, gives the expectant mother recommendations or prescribes additional procedures.

AFP, hCG and free estriol

It is by the 16th week of pregnancy that an increased or decreased level of a-fetoprotein in the blood makes it possible to accurately identify a neural tube defect and other defects indicated in the following table.

HCG (chorionic gonadotropin) - is produced first by the membrane of the embryo, then by the placenta.

If the hormone is normal, then the pregnancy is proceeding safely, but if the prenatal biochemical test revealed abnormalities, then there are several reasons for this, which are listed in the table below.

NEZ (unconjugated estriol, free) - the hormone is first produced by the placental membrane, then the fetus itself. With an increase in the duration of pregnancy, an increase in NEZ in the blood of the expectant mother occurs.

A significant decrease or increase in the hormone is a symptom of a pregnancy disorder or pathology of fetal development.

Deviations from the norm can be caused by the following reasons:

E3 - free estriol
Promoted	Downgraded
large fruit	Risk of miscarriage
Multiple pregnancy	Overbearing of the fetus
Risk of preterm birth (with a strong increase in EZ)	intrauterine infection
	Down syndrome
	Neural tube disorder
	Violation of the development of the internal organs of the fetus
	The pregnant woman took drugs prohibited in her position
	Feto-placental insufficiency

Correct interpretation of the results is very important. If the second screening confirmed that the data obtained is not within the normal range, it is imperative to consult a doctor.

Prenatal second screening does not exclude both false negative and false positive results.

Therefore, expectant mothers should not independently interpret the risks, which can, in the end, greatly affect their nervous system.

If the results of the prenatal second screening are very abnormal, then this fact should not be considered a verdict, at least until additional studies are carried out.

Every pregnant woman faces a 1st trimester screening and then a second trimester screening. When I was pregnant for the first time, I was told that I needed to get screened. What it is and why - they did not explain in detail, I had to look for information on the Internet myself. After all, it is important to properly prepare for this study so that the results are as reliable as possible. But even careful preparation will not give you a 100% guarantee of the correctness of the results.

Read in this article why screening in the 1st trimester, what studies this concept includes, how to prepare for them and how to decipher the results.

Screening - what is it?

Screening of the 1st trimester of pregnancy is a special study of the fetus for malformations. Screening is carried out from 10 to 13 weeks. In the antenatal clinic, absolutely all pregnant women are told about the need for such a study, they are given referrals. But a woman in position can refuse screening. In this case, she will be asked to write a written refusal.

I did both screening tests during my first pregnancy and I still remember how much I was worried and nervous. Because I knew a case when a woman was told that she would have a child with Down syndrome, but she did not have an abortion. As a result, a completely healthy baby was born. Can you imagine what she went through during those 9 months?

Unfortunately, there are also errors of the opposite nature. Not always screening can predict the birth of a sick child.

The screening itself consists of two studies - ultrasound and blood donation from a vein for biochemistry. Ideally, these two procedures should be done on the same day to get more accurate results.

It is most important to do screening in the 1st trimester for the following categories of women:

those who have had 2 or more miscarriages or premature births;
those who had a previous missed pregnancy;
who have relatives or children with genetic diseases;
age over 35;
if a woman had a viral or bacterial infection in the early stages;
if the woman was taking medications that should not be taken by pregnant women;
if the pregnant woman is in close family relations with the father of the child;
who has a “harmful” job;
with alcohol, tobacco and drug addiction.

What pathologies are detected at the first screening.

At screening in the 1st trimester, studies are carried out to identify such pathologies:

Down Syndrome. This is a chromosomal pathology, when in the 21st pair of chromosomes, instead of two, there are three chromosomes. This syndrome is not rare, there is 1 case per 700 fetuses. The risk of developing this syndrome increases with the age of the mother.
Patau syndrome. It is also a chromosomal pathology, when there is an extra copy of chromosome 13 in the cells. The frequency of birth of children with this syndrome is 1 in 7,000 or 10,000. Children born with this pathology in most cases die before the age of 1 year, because they have very severe developmental anomalies.
Edwards Syndrome. This is a chromosomal disease, when there are three chromosomes in the 18th pair of chromosomes. With this pathology, there are many different malformations. This syndrome occurs in 1 child in 5000-7000.
Smith-Opitz syndrome. This is a hereditary disease that is caused by gene mutations. This disrupts the metabolism of cholesterol, which is necessary for the embryo for the proper development of the brain, nervous system, limbs and other important functions. The frequency of the disease is 1 in 20,000-30,000.
triploidy. This is a rare chromosomal anomaly. In this case, instead of the required 46 chromosomes (23 from the father, 23 from the mother), the fetus has 69 chromosomes. In most cases, such pregnancies end in miscarriage, less often children are born alive, but with multiple disorders.
de Lange's syndrome. The cause of this disease is gene mutations. Damage to internal organs can be of varying severity.
Omphalocele. This is a severe malformation when the organs of the child's abdominal cavity (intestine and liver) are outside, in the umbilical cord, which is expanded.
Pathology of the neural tube.
Timing of screening in the 1st trimester and preparation for it.

The first screening should be done between the beginning of the 10th week and the end of the 13th week. And it is best to do it at 11-12 weeks. The gynecologist will tell you the best moment, based on the date of the last menstruation.

The first screening after 13 weeks can no longer be considered reliable.

Preparing for an ultrasound. This procedure can be done in two ways: transvaginally and abdominally.

The transvaginal method is considered more accurate than ultrasound through the abdomen. Such an ultrasound is done with a special sensor that is inserted into the vagina. In this case, a condom is put on the sensor, which is lubricated with a special gel. On such an ultrasound, it is determined whether there is a threat of miscarriage, whether there is a threat of placental abruption. Special preparation for such an ultrasound is not required, it is done on an empty bladder.

If you prefer to have an abdominal ultrasound (through the abdominal wall), you will have to fill your bladder. To do this, half an hour before the study, drink 0.5-1 l of water without gas and do not go to the toilet. For ultrasound in the second trimester, you no longer need to do this. It is desirable that the intestines be empty. That is, at least 4 hours before the ultrasound, you do not need to eat.

Preparation for blood sampling.

In order for the result to be as accurate as possible, you need to follow important rules. First, donate blood on an empty stomach. This means that at least 6 hours before this study, you can not eat. You can drink some water, but don't get carried away.

Secondly, one or two days before the delivery of this analysis, you need to “sit down” on a special diet. On this day, you can not eat anything smoked, fatty, fried, spicy. And also exclude chocolate, citrus fruits, seafood.

By the way, it is better to exclude chocolate, citrus fruits, strawberries from the diet of pregnant women altogether so that the child is not prone to allergies. You can’t eat fatty foods, because it will be impossible to get normal serum from your blood, and money for biochemistry will be wasted.

You need to come to donate blood with the results of an ultrasound scan, because the indicators in the blood test are closely related to the gestational age. You will receive the results of biochemistry in a week and a half.

Deciphering the results of the first screening.

Norms of ultrasound in the first trimester.

Coccyx-parietal size of the fetus (KTR). The rate depends on the duration of pregnancy. In the table, see the norms for this indicator.

Collar space thickness (TVP). This indicator is considered very important in the examination for genetic disorders.

The size of TVP more than 3 mm can be regarded as a risk of developing Down syndrome or Edwards syndrome.

Nasal bone.

This indicator is considered very important, because in Down syndrome this bone is not detected in the early stages.

Normally, at 10-11 weeks, this bone is already detected on ultrasound, but not measured. At 12-13 weeks, the nasal bone should be at least 3 mm. If this indicator is less than normal, and the collar zone is larger, then this may indicate the development of Down syndrome.

The heart rate (HR) of the fetus.

Biparietal size (BDP) is the distance between the parietal tubercles.

Also, ultrasound measures the size of internal organs, assesses the condition and placenta previa, and looks at the umbilical vessels. An ultrasound will determine the exact gestational age.

Deciphering the results of a blood test for hormones.

After the ultrasound, you will need to donate blood from a vein for hormones. Read the norms for a biochemical blood test in the 1st trimester here. This time, the blood is examined for two markers - β-hCG (human chorionic gonadotropin) and PAPP-A (protein A associated with pregnancy).

Chorionic gonadotropin.

If the levels of this hormone lowered, then this indicates a pathology of the placenta or an increased risk of Edwards syndrome. Increased the amount of these hormones can be with the development of Down syndrome. And also this hormone will be more than normal during pregnancy with twins.

RAPP-A. This is a protein that is produced by the placenta. The amount of these proteins increases with gestational age.

Also, when analyzing blood, they calculate the MoM coefficient. Normally, this coefficient is 0.5-2.5 at this stage of pregnancy. If the pregnancy is twins, then MoM can be up to 3.5.

If MoM is below 0.5 - this is interpreted as a risk of developing Edwards syndrome, MoM above 2.5 - the risk of developing Down syndrome.

How is the risk of congenital pathologies in the fetus calculated?

After passing the screening, you should be given the results of the examination. These results should indicate the risks for each individual syndrome. For example, Down's syndrome is a risk of 1:380. This means that women with the same screening results give birth to 1 sick child in 380 healthy ones.

Such a calculation is made using a special computer program, into which your ultrasound data, the results of a biochemical blood test, as well as age, individual characteristics of the body, concomitant diseases and pathologies, and harmful factors are entered. And already in the aggregate of all these parameters, the program calculates the risks.

It is believed that the risk of 1:250-1:380 is high. In this case, they are always referred for a consultation with a geneticist. For an accurate diagnosis, parents will be offered to undergo additional studies: amniocentesis or a biopsy of the chorionic villi. These studies can be life-threatening for the child (1% of children die after such an intervention). But after amniocentesis, with almost 100% guarantee, you will be told whether the child is healthy or not.

If the risk of pathologies is low, then in the second trimester the pregnant woman will be sent for the second routine screening.

What influences screening results.

As I wrote above, screening results can be erroneous. There are factors that can affect the final result.

If a pregnant woman has obesity, then the amount of hormones will be increased, although this does not indicate a pathology of the fetus. And in case of too little weight of the expectant mother, the amount of hormones will be less than normal.
With diabetes in the first trimester, the amount of hormones will be below normal. In this case, the results of the blood test will be unreliable.
If a woman is pregnant with twins, then she is only given an ultrasound, because the exact norms for hormones are unknown.
If pregnancy occurred as a result of IVF, the level of hCG will be higher than normal, and PAPP will be lower.
The emotional state of the examined woman can also affect. Therefore, it is better not to think about the bad, but to tune in to good results and not worry.

Features of screening in the first trimester.

Ultrasound screening for Down syndrome.

In this disease, in 70% of cases in the first trimester, the nasal bone is not visible. But you should know that sometimes this bone may not be determined in healthy children. The collar zone is more than 3 mm. Violation of the blood flow in the venous flow. Rapid heartbeat, bladder enlargement. The upper jaw is smaller than normal. Facial features are smoothed out.

Edwards Syndrome.

Heartbeat below normal. The nasal bone is not defined. One umbilical artery instead of two. There is an omphalocele (when some of the internal organs are outside in the hernial sac).

Patau syndrome.

Brain development is impaired. Heartbeat quickened. Omphalocele. The size of the fetus is smaller than expected at this time.

First trimester screening is best done in one place to get the most reliable results. Proper preparation for screening and a positive attitude also play an important role. Remember that screening is not a diagnosis. And in case of increased risks, only additional studies will help establish the truth.

Every year, medical research becomes more complex and detailed.

Even 10–15 years ago, the word “screening” did not mean anything to expectant mothers, and now this procedure is included in the mandatory set of examinations for every pregnant woman in our country.

In general, screening in medicine is a set of measures aimed at determining specific indicators responsible for a particular state of the body.

Perinatal screening is a diagnostic complex that helps to identify among pregnant women those who are at risk for abnormalities and pathologies of fetal development.

In total, during pregnancy, such a procedure is carried out twice and is called, respectively, the first and pregnancy.

The set of activities that make up this procedure includes:

an ultrasound examination of the fetus, designed to examine in detail how the baby develops;
blood sampling from a vein for biochemical analysis.

The first screening is considered the most important for determining risks. During diagnostics, the following parameters are measured:

the size of the collar zone of the fetus on ultrasound;
hormone levels: and plasma protein (PAPP-A).

Whether to do the first screening?

Of course, conducting such studies, although it is practically mandatory when registering in a antenatal clinic and highly desirable for providing in a maternity hospital, no one will forcibly pull the expectant mother by the hand for an ultrasound and blood sampling.

However, first of all, it is in the interests of the woman in labor. Why?

The first of the perinatal screenings is designed to identify the risks of congenital malformations of the baby in early pregnancy.

It is carried out in order to warn the expectant mother how high the percentage of her child is to have chromosomal pathologies, such as Down's disease, Edwards disease, defects in the structure of the nervous system, spinal cord or brain, which will later lead to the death of the fetus or its severe disability.

Such examinations are especially important for the following categories of women in labor:

under 18 and over 35 years old. Women of these age periods are most susceptible to the risks of the child and the expression of congenital malformations in the fetus;
previously given birth to children with genetic pathologies;
having hereditary diseases and genetic pathologies in the family;
previously had a history of,;
who worked in hazardous industries or who had previously been treated with fetotoxic (dangerous to the fetus) drugs.

For such women, the first screening is mandatory because they are at risk; All these factors can provoke deviations in the development of the child.

For the rest of the expectant mothers, the doctors, one way or another, still offer to undergo this procedure for their own reassurance: after all, knowing that everything is in order with the baby is very useful for well-being, and modern ecology and the health of the nation are not so good as not to undergo additional examinations.

When to do the first screening?

The first of the perinatal screenings is carried out between and. However, the most accurate result is obtained in the interval from to , when you can most clearly track serum hormone levels and baby collar size, and also at this time it is already clearly possible to track its structure, the development of internal organs and limbs using ultrasound diagnostics.

In addition, during this period, KTP - coccygeal-parietal size of the fetus, which helps to further clarify the timing of delivery and the compliance of the development of the baby with the expected gestational age.

Norms and indicators

What is it that diagnosticians look for during screening? Since this procedure consists of two stages, it is necessary to talk about each of them separately.

The first is usually diagnosed with an ultrasound machine. It is directed:

to determine the location of the embryo in the uterus to rule out the possibility of ;
to determine the number of fruits(whether singleton or), as well as the likelihood of a multi-ovular or identical multiple pregnancy;
to determine fetal viability; for a period of 10-14 weeks, it is already clearly visible, as well as movements of the limbs that determine viability;
to determine KTP mentioned above. It is compared with data on the last menstruation of a pregnant woman, after which a more accurate gestational age is automatically calculated. With the normal development of the fetus, the KTR term will coincide with the obstetric gestational age, set according to the date of menstruation;
for consideration of fetal anatomy: at this time, the bones of the skull, facial bones, limbs, the rudiments of internal organs, in particular the brain, are visualized, and the absence of pathologies of large bones is also determined;
to the most important in the first screening - determination of the thickness of the collar space. Normally, it should be about 2 millimeters. Thickening of the fold may indicate the presence of genetic diseases and defects. In addition, to detect pathology, the size of the nasal bone is considered, it can also show the presence of genetic defects in the fetus;
to determine the status of the placenta, its maturity, the method of attachment to the uterus, in order to understand the possible threats of pregnancy associated with its dysfunctions.

According to this ultrasound, biochemical studies of blood serum for the hormones hCG and PAPP-A are already being carried out. Their level can show the existing changes.

With an increased level of hCG, the following can be diagnosed:

multiple pregnancy;
pregnant women;
Down's disease and other pathologies;
incorrect gestational age.

Decreased levels of human chorionic gonadotropin usually speaks of an ectopic pregnancy, a possible fetal growth retardation, a threatened miscarriage.

PAPP-A hormone is a protein that is responsible for the normal functioning of the placenta.

Its decrease relative to the norm may be evidence of the following problems:

the presence of Down syndrome or Edwards;
the presence of genetic pathologies;
frozen pregnancy.

Bad performance

Finding out about poor performance is, of course, a huge stress for the expectant mother.

However, that is why screening consists of two stages: to use ultrasound, before shocking the woman in labor with a bad blood test, to eliminate the possibility of multiple pregnancy, inaccurate timing of its course, the possibility of a threatened abortion or ectopic pregnancy.

In addition, you should not immediately panic (even with frankly poor test results of the first screening). In addition to them, there are several more methods for determining genetic pathologies during pregnancy. Usually they are prescribed by a geneticist after screening data.

These may include amniotic fluid collection procedures or placental biopsy to clarify the data obtained during screening. Already on the basis of these additional diagnostic methods, one can speak of one or another presumptive diagnosis.

In addition, another way to check can serve as a second screening, which is carried out at a later date: on - pregnancy. After these studies, the picture will become as clear as possible.

In any case, it should be remembered that the first perinatal screening is not the final diagnosis for the baby. It is intended only to calculate the risks and make assumptions about the possible development of events.

The data obtained from the results of screening is neither a verdict nor the ultimate truth.

In addition to objective indicators, there is always the possibility of research errors and individual characteristics of the pregnant woman’s body, in which the screening indicators will be different from the norm, but the fetus will develop completely normally.

Therefore, even with the most unfavorable forecasts, there is a chance that they will not come true.

- a mass examination of women, which is done at a period of 11-13 weeks of pregnancy. The first screening allows you to identify congenital anomalies in the development 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). Screening is subject to all pregnant women without exception. At the same time, a woman has the right to refuse such an examination. But, it should be remembered that failure to screening can lead to adverse pregnancy outcomes.

When is screening mandatory?

There are risk groups for pregnant women who must undergo prenatal diagnosis without fail.

The first screening is carried out in such cases:

All women over the age of 35.
If in the past there were miscarriages or non-developing (frozen) pregnancies.
In the presence of harmful professional factors.
Risk 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 relationship between the parents of the unborn child.
Women who have taken pharmaceuticals that are contraindicated for use during gestation.

Procedure for the first screening

To pass a reliable first screening, the 1st trimester has certain limits 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 11-12 weeks. It is very important that the deadline is set correctly. This will be done by a gynecologist and will determine when it is better to undergo the first screening.

In order to undergo a perinatal examination, it is necessary to properly prepare for examinations. If ultrasound is performed with a vaginal probe, then special preparation is not required. If ultrasound is done through the abdomen, the following rules must be observed:

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

If a non-developing pregnancy is detected on ultrasound, the examination is terminated.

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

Before you donate blood, you must definitely do an ultrasound of the fetus. This is the most important condition, since the indicators in the biochemical blood test directly depend on the gestational age.
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 taking a blood test.
A couple of days before the biochemical examination, all potential allergens should be excluded from the diet. They can be seafood, nuts of any kind, chocolate. Also, do not eat 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 at the first screening?

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

Down syndrome is the most common genetic anomaly.
Lange syndrome. It is characterized by multiple malformations. If the baby survives, then he has a profound mental retardation.
Patau syndrome. It is characterized by severe damage to the organs of the child. Such children die in the first months after birth.
Edwards Syndrome. An ultrasound revealed 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 region of the umbilical ring, which includes internal organs.
Anencephaly is the absence of the brain.

All transcripts according to the results obtained are done by a gynecologist.

Deciphering the results of ultrasound during the first screening

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

The distance from the crown to the coccyx (KTR), which normally ranges from 33 to 73 mm, depending on the gestational age. Below is a table that shows the KTR standards:

fetal TVP (collar space thickness).

Normal 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 norms of TVP:

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

The size of the nose bone.

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 (BDP).

With ultrasound, this size is determined as the distance between the parietal tubercles. By the end of the first trimester, the result of BDP is normally more than 20 mm.

Fetal heart rate.

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

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

Deciphering 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 specific fetal hormone. Screening of the 1st trimester allows you to determine its maximum values. Determination of the level of β-hCG allows the most reliable calculation of the risk of Down's disease. Below is a table that shows the normal values of the level of β-hCG:

It is important to remember that in different laboratories, the normal values of the level of β-hCG may differ.

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

Do not forget that the PAPP-A values \u200b\u200bin each laboratory are also different.

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

Calculation of perinatal risk

In order for the screening of the first trimester to be as reliable as possible, it is necessary to take tests and undergo ultrasound in the same 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 comorbidities. The data obtained is entered into a computer, into a special program that calculates the risks. The program gives the final result in the form of a fraction. For example, the program issued a risk of 1:400. The decoding will be as follows: out of 400 pregnancies with the entered indicators, 1 baby with a pathology will be born. Depending on the value obtained, the conclusions can 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 an additional examination to establish or refute the diagnosis is being decided. In this case, an amniocentesis or a biopsy of the chorionic villi is done.
Negative test. This means that the risk of pathologies is low and there is no need to conduct an 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 the fetus can be assumed as early as 10-11 weeks. When conducting an ultrasound, the following characteristic signs of this syndrome are revealed:

TVP thickening more than 3 mm. Deviation of TVP from the norm can also indicate other genetic disorders.
No nasal bone in 70% of cases. It is important to know that in healthy children in the early stages, the nasal bone may not be determined.
Violation of blood flow through the ductus arteriosus.
Hypoplasia (reduction) in the size of the upper jaw.
Bladder enlargement.
Raised fetal heart rate.
Pathology of the vessels of the umbilical cord: one artery and one vein.

Screening of the first trimester is an important stage of examination during gestation. With its help, it is possible to 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 recommendations of the doctor and undergo screening on time.

If the screening results reveal a high risk of pathologies, do not panic. It is necessary to contact a specialist who will prescribe an 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.