How screening analysis is done. Biochemical screening of pregnant women is not so scary

First trimester screening is a type of prenatal examination of a pregnant woman, which allows you to identify possible risks birth of a sick child. The diagnostic test consists of fetal ultrasound and venous blood donation. The results obtained are compared with normal values, and depending on the individual factors of the pregnant woman, the geneticist predicts the chances that the child will be born with chromosomal diseases.

Now let's look at this in more detail.

Who is referred for first trimester screening?

In accordance with the order of the Ministry of Health of the Russian Federation No. 457 of December 28, 2000, all pregnant women should be sent for screening in the first trimester, especially if the woman is at risk:

• over 35 years old;
• suffered unsuccessful pregnancies in the past, which ended in miscarriage or miscarriage;
• works in hazardous production;
• already has a child with genetic diseases, or in previous pregnancies, chromosomal abnormalities and intrauterine defects were identified during screening in the first trimester;
• suffered an infection at the beginning of pregnancy;
• took medications that are prohibited in the first trimester;
• suffers from drug addiction, alcoholism;
• if there is a threat of miscarriage;
• potential parents are close relatives, or there were cases of hereditary diseases in their family.

Of course, a woman can refuse to undergo the analysis, but it would be reckless to do so, because the health of the unborn child depends on this.

Ultrasound as part of screening

Ultrasound examination allows to identify and determine:

• hypertonicity of the uterus;
• examine the internal os of the uterus;
• localization and thickness of the placenta;
• fetal heart rate (HR);
• coccygeal-parietal size (CTD) is the distance from the head end of the fetus to its tailbone, not taking into account the length of the lower limbs;
• biparietal size (BPR) - circumference of the fetal head;
• structure of the brain;
• thickness of the cervical fold or nuchal space (TVP);
• length of fetal limbs;
• localization of the stomach and heart;
• parameters of the heart, veins and arteries;
• volume amniotic fluid;
• number of umbilical cord vessels.

What pathologies can be detected by ultrasound?

Ultrasound screening of the first trimester allows you to identify pathologies such as:

• trisomy 21, better known as one of the most common genetic diseases, thanks to this study, the frequency of births of children with this pathology has decreased and if previously 1 child was born out of 700 pregnancies, now out of 1100;
• trisomy 13 or , up to 95% of newborns due to the lesion internal organs die in infancy;
• Edwards syndrome or trisomy 18, the risk of having such a child increases with age, most children with such abnormalities die in the first year of life due to cardiac or respiratory failure;
• embryonic hernia is a pathology characterized by the fact that some of the internal organs are located outside the abdominal cavity in the hernial sac;
• Brachmann-Lange syndrome, a disease that manifests itself as a delay in mental and physical development;
• Smith-Lemli-Opitz syndrome, the clinical picture of the pathology can vary greatly, such children may experience mental retardation varying degrees heaviness;
• neural tube defects (craniocerebral hernia, spina bifida, etc.).

The thickness of the nuchal translucency will help determine the likelihood of developing Down's disease. This indicator is determined during an ultrasound, but the exact result is determined after the blood test parameters are established.

A blood test involves determining the following indicators:

1. Hormone. Normally, this value gradually increases with the development of pregnancy. If the obtained indicator significantly exceeds the norm typical for a particular week, there is a risk of developing, if the values ​​​​are lower - .
2. An indicator of plasma protein concentration. Deviations from the norm indicate the presence of a risk of developing pathologies in the future.

Ultrasound examination during the first screening allows you to determine:

• Availability ;
• location of the fetus in the uterine cavity;
• establish multiple or singleton pregnancy;
• view embryo viability indicators;
• determine fetal CTE;
• the presence of defects and pathologies of internal organs;
• check the indicators of the collar space (the norm for the 10th week is 2 cm).

A comprehensive examination allows you to confirm or refute the presence of genetic-chromosomal disorders of the fetus.

For precise definition Indicators of fetal viability also undergo biopsy and aminocentesis. In any case, the data obtained during the screening examination cannot become the main reason for termination of pregnancy. It is important to conduct a complete examination in order to prevent making an erroneous decision.

Attention! If anomalies are detected in which further normal life child is impossible, the girl may be offered termination of pregnancy.

Based on this information, it is worth emphasizing that screening is a necessary diagnostic method. Mothers should remember that refusal to conduct the study can be issued, but the consequences may be irreversible.

Time frame for the study

Diagnosis should be carried out at a gestational age of 10-14 weeks. If you do screening earlier or later, the results will be incorrect.

In this case, the CTE of the fetus must be at least 45 mm. Its position should allow the uzist to evaluate all fetometric parameters. If the fetus is positioned poorly, the pregnant woman is asked to cough or walk around so that it changes its position and allows the doctor to examine its size.

Rules for preparing for research

The study consists of two stages: ultrasound and blood donation.

1. First, the woman must undergo an ultrasound. It can be performed transvaginally (no special preparation is needed) and transabdominally, while bladder women should be plump. Why should she not urinate for at least 2 hours before the ultrasound or should she drink 1.5 liters of water 30 minutes before the examination. Also, 1-3 days before the ultrasound, seafood, chocolate, citrus fruits, fatty and fried foods should be excluded from the diet.
2. After the ultrasound, the woman is sent to biochemical screening, her blood is taken from a vein; it must be donated on an empty stomach. To donate blood you should prepare:

• The last meal should be no later than 4 hours before blood donation.
• You should follow a diet for several days to avoid accidental distortion of study data.
• A woman should remain in a calm state.

No special preparation measures are required, but the recommendations given must be followed. Some restrictions will reduce the risk of unintentional distortion of survey results.

How the study is performed

An ultrasound examination is performed by a sonologist - a specialist in a narrow focus in diagnostics. The employee is specifically engaged in perinatal examinations. Ultrasound at 10–12 weeks can be performed abdominally and transvaginally.

The transvaginal examination method is most often chosen. To conduct the examination, a woman should remove her clothes from the waist down and lie down on the couch with her legs bent. To conduct the examination, the doctor inserts a thin sensor in a condom into the woman’s vagina, which will be moved during the examination. A woman may experience slight discomfort, but not pain. After conducting the study, a woman may find that there is no a large number of discharge interspersed with blood is natural, there is no cause for concern.

The tansabdominal examination method is used less frequently. Doctors say that in the early stages this method may cause some error. To conduct the examination, the woman lies down on the couch and lifts her clothes in the abdomen. If there is a belt around the hips, it should be removed. With this examination method, the sensor is moved across the abdomen. The patient does not experience discomfort or pain.

Screening involves not only an ultrasound scan, but also blood donation. The material for the study is the woman’s venous blood. The sampling is carried out in a specialized laboratory. About 10 ml of material is sufficient to conduct the study.

Attention! Blood is donated after an ultrasound. The doctor will need the results of an ultrasound examination to correctly interpret laboratory parameters.

Most often, private clinics provide results on the same day. The advantage of undergoing screening in commercial institutions is that the center provides the woman with a video recording of the ultrasound. Government agencies Due to the large flow of patients and high workload, results are processed within 3-5 days.

Decoding the results

To correctly decipher an ultrasound, you need to know normal indicators:

1. CTE is measured in millimeters. At week 10, the indicator can vary from 33 to 41 mm, at week 11 - from 42 to 50 mm, at week 12 - from 51 to 60 mm, at week 13 - from 62 to 73 mm. If this indicator is too high, then most likely the pregnant woman will have to bear and give birth to a large baby. When the indicators are below normal, then either the gestational age is set incorrectly, or the fetus has a genetic pathology, or it lags behind in development due to a deficiency of hormones, diseases of the mother, including infectious ones;
2. TVP at week 10 it can vary from 1.5 to 2.2 mm, at week 11 - from 1.6 to 2.4 mm, at week 12 - from 1.6 to 2.5 mm, at week 13 - from 1.7 up to 2.7 mm. With genetic abnormalities, as a rule, the collar space is expanded.
3. The nasal bone is visible at 10-11 weeks, but its size is not determined; at 12-13 weeks it should be at least 3 mm.
4. The fetal heart rate at 10 weeks should be from 161 to 179 beats per minute, at 11 weeks it can vary from 153 to 177 beats, at 12 weeks - from 150 to 174 beats, at 13 weeks - from 147 to 171 beats.
5. BDP: at 10 weeks - 14 mm, at 11 - 17 mm, at 12 - 20 mm, at 13 - 26 mm. If the value is higher than normal, then this may indicate a large fetus, while other values ​​should also be overestimated. Also, inflated results may occur with a brain tumor (this pathology is incompatible with life), with dropsy of the brain caused by infections in the woman (with adequate antibiotic therapy, pregnancy can be saved).

Based on the data obtained, the doctor makes a conclusion whether the development of the fetus is normal.

What hormone levels are determined by 1 screening?

In addition to ultrasound, first trimester screening includes a biochemical blood test, which allows you to detect hormone levels:

1. Human chorionic gonadotropin or “pregnancy hormone”, it begins to be produced immediately after conception. When the result of prenatal diagnostics is below normal, this may indicate or placental disorders. High rates are typical for multiple pregnancies and. measured in ng/ml: at week 10 it can vary from 25.8 to 181.60, at week 11 its values ​​should be from 17.4 to 130.3, the norm at week 12 is from 13.4 to 128.5, at 13 weeks - from 14.2 to 114.8.
   PAPP-A or pregnancy associated protein A, which is produced by the placenta, its level increases with increasing gestational age.

How to make sense of the data

There is a special program into which the indicators obtained during ultrasound and blood biochemistry are entered and it calculates the final result, called “risks”. On the form they are written in the column “MoM” - a coefficient showing the deviation of the values ​​​​of a particular woman from the average normal values ​​​​(medians).

If there are no pathologies, then the MoM values ​​should be in the range of 0.5-2.5; in the case of a multiple pregnancy, the MoM can reach 3.5. It is better if it is closer to 1. When calculating this coefficient, you need to take into account age-related risk. This means that the results obtained are compared not just with the median characteristic of this gestational age, but also calculated taking into account the age of the potential mother.

On the results form, the hormone level can be written in MoM units, for example, “HCG 1.58 MoM”, “PAPP-A 0.71 MoM”.

If the indicators are less than 0.5, then this may indicate a high probability of having a child with, the threat of miscarriage, placental insufficiency. When it goes beyond the upper limit of normal, there is a high risk of trisomy 21.

If the PAPP-A indicators are underestimated, then there is a risk of having a child, Edwards, Brahman-Lange. Isolated overestimated results have no diagnostic value.

Risk assessment

After the test results are received, the risks of having a child with anomalies are assessed. They are expressed in fractions, for example, 1:260, which means that 1 pregnant woman has a 260 chance of having a child with genetic abnormalities.

At low risk, these values ​​should be greater than 1:380, and the screening result is negative. With such results, it means that the child is healthy.

The first screening is considered bad if the risk is high, its level is from 1:250 to 1:380, and the MoM is also outside the normal range.
In this case, the pregnant woman is referred to a geneticist, who chooses further tactics:

• wait for the screening results of the 2nd and 3rd trimester;
• refer for additional examinations: chorionic villus biopsy, fetal umbilical cord blood examination, study of amniotic fluid, and based on their data, the doctor will decide whether to continue the pregnancy.

What can distort the result

Screening results may be false positive:

1. If pregnancy occurs as a result of artificial insemination, then on ultrasound the fronto-occipital size of the fetus will be increased, an overestimation of the hCG value in the blood will be detected, while PARR will be 10-15% less.
2. In overweight women, the concentration of all hormones increases, and in underweight women, the concentration decreases.
3. Currently, normal indicators for multiple pregnancies are unknown. In this case, only ultrasound is performed.
4. If a woman suffers, the concentration of hormones will be below normal.
5. When performing amniocentesis (puncture of amniotic fluid), prenatal diagnostic indicators may change. And since it is not known what the normal values ​​should be, at least a week should pass between these two studies.
6. The emotional state of a woman: fear can affect the final result, and no one can say how.

Some features of fetal anomalies

If the fetus has any pathologies, then screening will have a number of features:

1. . It is characterized by the fact that at a gestational age of 10-14, the nasal bone is not visualized in most fetuses, and at a period of 15-20 weeks it is visible, but it is shorter than normal. In addition, you can notice that the fetus’s facial features are smoothed, there is a disturbance in blood circulation in the venous duct, and the size of the bladder is increased.
2. The following deviations from the norm are characteristic: the nasal bone is not visible, there is a hernia of the umbilical cord, the umbilical cord has one artery, not two, the heart rate is below normal.
3. With Patau syndrome, the doctor can examine a fetal hernia, the structure of the brain is changed, the size of the fetal bones is smaller than it should be normally, and an increased heart rate is almost always observed.

Some features of pathology

It should be borne in mind that some deviations in the results may not indicate the presence of pathology.

Minor deviations are natural for the following groups of patients:

• persons suffering from systemic diseases;
• with artificial insemination;
• in overweight patients;
• during multiple pregnancy.

Cost of 1st trimester screening

The cost of the examination may vary significantly depending on the region Russian Federation. A similar service costs slightly more in private medical centers.

The cost may be paid separately:

• blood test - 1700-3600 dew. rub;
• Ultrasound – 1200-2700 ros. rub.

Women should remember that pregnancy is not only expected and desired, but also a dangerous condition that requires constant medical supervision, and screening examination is the most effective method detection of fetal pathologies early stages.

Biochemical screening is an analysis of a complex of serum markers during pregnancy, which allows one to assess the likelihood of developing a number of pathologies in the fetus. To do this, in the treatment room, about 20 ml of blood from a vein is taken from the expectant mother and sent for testing to a laboratory equipped with automatic analyzers to determine hormonal markers.

Why is it worth undergoing biochemical screening?

The level of some hormonal markers in the blood of a pregnant woman is closely related to the development of the child. The task of biochemical screening is to determine the level of hormones that are affected by chromosomal diseases of the fetus. The screening test does not provide a definitive diagnosis, but does indicate an increased risk of having Down, Edwards or Patau syndrome. The study is carried out in the first trimester of pregnancy.

Biochemical screening 1st trimester

It is carried out at 11-14 weeks of pregnancy. Before the ultrasound examination, the gestational age is determined. If the period is determined incorrectly, the analysis will show an erroneous result. If biochemical screening shows a high risk of chromosomal pathologies, the doctor may prescribe repeated biochemical screening in the second trimester or invasive diagnostics to verify the diagnosis.

Indications for biochemical screening

Even the young and healthy parents there is a risk of having a child with chromosomal pathologies, so it is recommended that every woman undergo biochemical screening, regardless of age and risk group. Risk groups that are especially recommended to undergo the study:

• The mother’s age is over 35 years, the father’s is 45 years old;
• Genetic abnormalities in parents or their blood relatives;
• Birth or miscarriage of a child with developmental defects;
• Mother and father are related by blood.
• Unfavorable medical history: miscarriages, missed and regressed pregnancies;
• Infectious diseases suffered before the 10-11th week of the current pregnancy;
• Taking medications prohibited for pregnant women in the first trimester.

Contraindications to biochemical screening

• Excessive or insufficient body weight of a pregnant woman;
• Multiple pregnancy;
• Diabetes mellitus in the expectant mother;
• Pregnancy as a result of IVF.

These conditions affect the level of the hormonal markers being studied, so biochemical screening will show an incorrect result.

Norms for biochemical screening

Each marker has its own standards, deviations from which indicate problems. After decoding all the results and an integral assessment, taking into account the age of the expectant mother, the overall risk of chromosomal pathologies in the fetus is determined:

• • Risk 1:10000 and below. Low risk pathologies, the child is healthy.
  • Risk from 1:1000 to 1:10000. Average risk of developmental defects.
  • The risk is higher than 1:1000. There is a high risk of genetic abnormalities; the pregnant woman is prescribed additional tests.

How to confirm the diagnosis

The only way to confirm the diagnosis is invasive diagnostics, which involves puncturing the abdominal wall and collecting fetal genetic material for research. In the first trimester, chorionic villus biopsy is performed, in the second - amniocentesis and cordocentesis.

Invasive diagnostics gives a 100% reliable result, but has a number of risks, which are very low in percentage terms, but gain significance given the mass coverage of pregnant women.

Increasing the information content of first trimester screening

There is the possibility of using a more accurate screening test, namely non-invasive prenatal testing. These include the Prenetix test we use.

Prenetix is ​​a non-invasive testing developed by the Russian laboratory Genetico based on the American Harmony technology - the most reliable way to determine the risk of chromosomal pathologies. The test examines fetal DNA contained in the blood of the expectant mother from the first weeks of pregnancy. From the tenth week their concentration is sufficient to carry out the test.

The test does not require preparation; it is enough to donate 20 ml of venous blood at any representative office of the Genetico laboratory. The accuracy of the test is 99.2% (for Down syndrome), and is confirmed by dozens of studies in which more than 22,000 women from all over the world took part.

The patient will receive a result by email that will show whether the fetus is at risk of having the following chromosomal abnormalities:

• Down syndrome
• Edwards syndrome
• Patau syndrome
• Shershevsky-Turner syndrome
• Klinefelter syndrome

Our specialists provide advice on the appointment and interpretation of NIPT results.

The first perinatal screening is a comprehensive diagnosis of the expectant mother, which is carried out even before the birth of the baby from 10 to 13–14 weeks of intrauterine development. A classic study of this kind combines only 2 main types of medical manipulations - biochemical analysis of maternal serum and ultrasound of the fetus.

Upon completion of the tests, monitoring of the obtained data will be carried out, based on a comparison of the result with the indications of the 1st trimester ultrasound screening norm. The main goal of an individual examination is the early detection of genetic pathologies in the fetus.

Indications for use

Despite the fact that primary diagnosis is carried out for many pregnant women, there are special categories of patients who are first required to undergo an ultrasound and blood test in order to exclude a danger to the life of the unborn child and their own health. This group of people includes expectant mothers who:

• previously gave birth to children with any developmental disabilities;
• already have a child with documented genetic pathologies;
• crossed the threshold of 35–40 years;
• were exposed during pregnancy infectious diseases;
• have ever suffered from excessive use of alcohol or drugs;
• have a medical history with notes about the threat of spontaneous miscarriage;
• are in a consanguineous union with the potential father of the baby;
• accepted for any reason medications, prohibited for use during gestation;
• know about the presence of hereditary anomalies in the family pedigree;
• have experienced a stillbirth in the past;
• received a diagnosis indicating the cessation of the child’s development;
• demonstrate an independent desire to analyze the risk of having an infant with specific forms of the disease.

Smoking during pregnancy is the basis for mandatory screening in the first trimester

How are the results of a fetal screening ultrasound interpreted?

Ultrasound diagnostics are prescribed, as a rule, from 10–11 weeks to 13–14 weeks, since this period of obstetric period provides the first real opportunity to study the main structures of the developing baby. Week 11–12 is a special period characterized by the transformation of the embryo into a fetus.

There is a list of the most important indicators of fetal development, which formed the basis for deciphering the ultrasound report. These include: KTR, PAPP-A, heart rate, BPR, TVP, hCG, NK, etc. In order to establish an accurate prognosis for the course of pregnancy, a specialist needs to compare the personal data of his patient obtained during the first screening with the approved standards that are prescribed in the corresponding tables.

Coccyx-parietal size

CTE is one of the most important screening indicators during pregnancy. This parameter indicates the length of the embryo/fetus, which is measured from the crown (top of the head) to the coccygeal bone. If the CTE deviates from its normal range, it can be assumed that intrauterine development the unborn child is at risk.

According to medical observations, the digital designation coccyx-parietal size increases with increasing gestational age. Sometimes a decrease in the index in question indicates an incorrectly determined age of the fetus. In this case, we can talk about one of the varieties of the norm. In order to confirm the diagnosis, the patient should make an appointment for the 2nd ultrasound appointment.

CTE is one of the main indicators of fetal condition

Heart rate

The state of the heart rate requires regular medical monitoring, since if there is a baby in the body pathological processes they will be discovered in time. If the anomaly is detected at an extremely early stage of its development, the likelihood of a favorable outcome will increase.

Up to 3–4 weeks, the baby’s CV rhythm coincides with his mother’s heart rate. The average value ranges from 76 to 84 beats per minute during normal functioning of a woman’s body.

Further, when the fetal cardiac structure moves to new stage natural improvement, the number of its contractions will begin to increase evenly. Every 24 hours the value will exceed the previous “record” by approximately 2.5–3 units. So, by 8–9 weeks, the heart rate of a child developing according to the approved norm will reach 172–176 beats/min.

If before 83–85 days of gestation with ultrasound diagnostics If dangerous phenomena such as fetal deformation or the complete absence of a heartbeat were not recorded, then a frozen pregnancy can be excluded from the list of possible pathologies. The subsequent phases of the formation of the body are less difficult than the 12-week “Spartan marathon”.

Provided that improved and high-quality models of medical devices were used for screening, potential parents will be able to obtain a more informative description of the child’s current condition. You should not resort to 3D/4D ultrasound unless absolutely necessary. Although such modern devices can record intrauterine activity and the baby’s appearance, their dose of radiation if ultrasound is abused can negatively affect the child’s health.

Nasal bone length

Changes in the structure of the oblong nasal bone also indicate the presence of abnormalities. Studying the condition of fetuses who were diagnosed with congenital ailments, scientists came to the conclusion that a genetic failure is often expressed in the underdevelopment of the bone structures of the nose. The first screening during pregnancy to determine the length of the nasal bone (NB) is carried out no earlier than 12–13 weeks. If the doctor ordered an ultrasound session at 10-11 weeks of pregnancy, this means that he only needs to make sure that the nasal bone is present.

In medical practice, there are often significant deviations from the ultrasound ultrasound norm, which in fact turned out to be a manifestation of the individuality of the unborn child. In this case, the indicators of other tests will correspond to the standard.

Collar thickness

The main objective of the TVP study is to measure the thickness of the fold located on the back of the neck. When the main organ systems of the fetus are formed, the area of ​​the collar space begins to fill with a special liquid, the amount of which is subjected to careful analysis.

If the indicator at the first screening exceeded a thickness of 3 millimeters, then damage to chromosomal segments can be suspected with a high degree of probability.

Study of the structure of the yolk sac

In simple terms, yolk sac is a temporary organ that helps maintain the life of the embryo at the initial stage of its formation. From the moment of conception, this important neoplasm is several times larger in size than the size of the unborn baby.

It should be noted that screening detection of deformation of the yolk vesicle or an overestimated/lowered indicator in most cases indicates the development of a dangerous disease, for example, Down syndrome. Sometimes, under such circumstances, a frozen pregnancy is diagnosed - premature death of the embryo.

You should not neglect the 1st screening, since with its help the sonologist will be able to examine the unique structure more carefully, making appropriate conclusions about its condition. If the yolk sac is at risk of destruction, immediate medical intervention is necessary. This is due to the fact that the bubble formed only for 3–3.5 months controls many processes in the child’s body.

Its most significant functions include:

• identification of extremely important protein structures involved in the construction of protective membranes for embryonic cells;
• the formation of a capillary network and red blood cells, which will become the “foundation for laying” the fetal circulatory system;
• temporary liver replacement;
• determination of the child’s gender by delivering to him gametes produced in the cavity of the yolk sac.

This organ is also responsible for protecting the small organism from the mother’s antibodies. No matter how controversial it may sound, cells immune system women, like soldiers guarding human health, attack the fetus, seeing it as a potential threat - a foreign element. In order to provide the embryo with a safe living environment, the yolk sac actively secretes hormones that begin to participate in the process of lowering blood pressure, “pacifying” immune resistance and preparing the mammary glands for breastfeeding.

After 12–14 weeks, the bubble stops its activity, gradually transforming into a cyst-like inclusion localized near the umbilical cord

Location of the placenta

The localization of the placenta influences the course of the upcoming pregnancy, therefore, during a comprehensive examination, a lot of time is devoted to it. According to the medical standard, this organ should not be located in the lower region of the uterus, since its abnormal structure provokes blockage of the birth canal. This common gynecological deviation is called presentation.

Detection of the disease during the first screening early pregnancy is not always a cause for concern. At an early stage, there is still a chance to change the extremely precarious position - in the subsequent period of gestation, the uterus may rise, taking its proper place. If a favorable outcome is not observed, doctors begin to develop a detailed action plan, which implies individual indicators for a particular patient.

Biparental fetal head size

BDP is an extremely important index, which is also included in the results of the first screening. Without going into details of medical terminology, we can say that this indicator implies measuring the head along the minor axis - the distance from one temporal bone to the other. The biparental size of the fetus is of particular value, primarily due to its direct relationship to the brain, located in the cranium.

Since this organ is the main element of the central nervous system, as well as the central processor of the body system, its condition depends on special attention is observed by a specialist conducting an ultrasound examination.

If no suspicious signs are observed in the final screening data, then the brain develops normally. A low index indicates a deficiency in any part of the brain or a delay in its development.

Blood chemistry

After the results of ultrasound diagnostics are received, on the basis of which the actual gestational age is determined, the pregnant woman will have to undergo the final stage of the perinatal examination - blood biochemistry. Screening involves conducting 2 tests, each of which helps to identify elements of protein origin - PAPP-A and hCG.

2–3 days before the blood biochemistry of the expectant mother, it is recommended to reduce the amount of consumption of fast food, spices, nuts, fatty foods, chocolate and confectionery

PAPP-A is a special hormone (plasma protein A) responsible for the gradual and safe development of the child in the womb. Usually, indicators about its content are determined only from 12–13 weeks, however, as an exception, the blood sampling procedure is carried out a little earlier.

Human chorionic gonadotropin is also a hormone that, unlike protein A, begins to be produced immediately after conception. It is noteworthy that its amount actively reaches its maximum value at 11–12 weeks, then the level of hCG gradually decreases, fixing at a stable level.

As soon as the patient undergoes perinatal screening in full, doctors will begin to compare the identified indices with the norm, drawing up a full final conclusion.

What pathologies can be detected during the first screening?

With the help of a comprehensive study in the first trimester, one can discover a fairly impressive list of pathologies that cause complications of varying severity, ranging from deformation of an organ to the death of the baby. The most frequently identified ailments include:

• hydrocephalus;
• glioma;
• Down syndrome;
• cerebral hernia;
• astrocytoma;
• Shershevsky-Turner syndrome;
• omphalocele;
• aneurysm;
• Patau syndrome;
• bradycardia;
• meningocele;
• intrauterine infection;
• Edwards syndrome;
• hypoxia;
• tachycardia;
• Smith-Opitz syndrome;
• developmental delay;
• anemia;
• hemimelia (underdevelopment of the limbs);
• Cornelia de Lange syndrome;
• heart disease.

Only a doctor has the right to diagnose the above congenital diseases, since the interpretation of an ultrasound performed by the patient independently may be done incorrectly. Forming a diagnosis based on the indicators of the first screening implies a comprehensive qualitative analysis of all data obtained, taking into account every aspect and pitfall. That is why expectant mothers are advised to trust their health and the life of their baby only to a professional. Constructive unity between the patient and the attending physician increases the likelihood of having a healthy child.

Biochemical screening, what kind of analysis is it? This is an analysis that shows whether the child has chromosomal abnormalities. It is not done for everyone, but for those who are at risk.

Biochemical screening, what kind of analysis is it? Every woman wants to give birth healthy child. But, even if she took care of herself and followed all the doctor’s instructions, the specialist cannot guarantee that everything will be fine with the baby. It is harmful to worry during pregnancy, so you can immediately dispel or confirm your doubts. You just need to take a referral for biochemical screening. What kind of examination is this, how to take this test, how long should you wait for the results? It helps to detect chromosomal pathologies that indicate a particular disease.

Biochemical screening is not prescribed to everyone. What kind of analysis is this and how is it taken? You will have to donate blood from a vein. When is it done? The first test must be taken during the first trimester. First, the woman is sent for an ultrasound examination. What kind of inspection is this? The specialist measures the fetus, looks at the condition of the uterus, and monitors the child’s well-being. Then compares the results with the standards. If they deviate from the norm, this is already a reason for additional examinations. If abnormalities are detected by ultrasound, biochemical screening is prescribed. To carry out the analysis, it is necessary to take the mother's blood serum. The results of blood tests show whether there are any abnormalities.

Is this test recommended for everyone? During pregnancy, those who are at risk must undergo it. But most experts say that it should be prescribed to everyone, because... Any woman can have genetic disorders. Therefore, WHO recommends that during pregnancy, everyone be sure to take a referral and get tested during the second trimester. But this is decided by the woman herself. But those who are at risk will have to undergo biochemical screening. Before taking the test, the doctor must know how many children the woman has and whether they are all healthy, how many miscarriages she has had, how many years she has been pregnant, how she felt at the beginning of pregnancy, and whether she took any medications.

This blood test must be prescribed:

1. During pregnancy that occurs after 30 years of age (first pregnancy) or after 35 years of age (second or subsequent pregnancy).
2. The woman has had 2 or more miscarriages before.
3. The pregnant woman or her husband has genetic abnormalities, or they have appeared in one of their children or relatives.
4. Before this, a child had already been born in the family and died due to developmental defects.
5. During the first trimester, the woman suffered from an infectious disease.
6. The child's parents or one of them suffered from radiation exposure, or a pregnant woman was exposed during the first trimester.
7. Close relatives conceived a child.

First screening during pregnancy- a set of examinations aimed at identifying the risk of congenital pathologies of the fetus. The diagnostic test includes an ultrasound and a blood test from a vein. Optimal timing for its implementation coincide with the end of the first trimester of pregnancy.

Prenatal screening shows the risk of pathology in the unborn child, but it cannot say with one hundred percent probability about its presence or absence. Deviations from the norm in its results are an indication for other diagnostic studies, during which specialists will make a final diagnosis.

Using 1st trimester screening expectant mother can find out about a severe congenital anomaly of the fetus and decide in time to terminate the pregnancy.

Time frame for completing the study

Screening in the first trimester of pregnancy can only be carried out from the first day of the 11th week to the sixth day of the 13th week. Conducting studies at an earlier date is not advisable, since the structures examined on ultrasound are still too small to be observed, and the hormones of the biochemical test have not reached the required concentration.

Carrying out ultrasound examinations for more later doesn't make sense. This phenomenon is due to the fact that after the fetus begins to develop the lymphatic system, the fluid of which interferes with the examination of anatomical structures.

The optimal timing for the first screening corresponds to 11-12 weeks of pregnancy. At this time, biochemical tests have the smallest error, and with the help of ultrasound equipment, the anatomical structures of the unborn child are clearly visible. Also, if developmental defects are detected, a woman can have time to undergo a medical termination of pregnancy in a low-traumatic way.

Indications for ultrasound and blood tests

According to the order of the Ministry of Health of the Russian Federation, 1st trimester screening is recommended for all pregnant women. It helps to identify malformations in the early stages of pregnancy and is absolutely safe for the fetus and expectant mother. Every pregnant woman has the right to decide whether she will undergo prenatal screening.

Mandatory first screening is recommended for women who are in one of the risk groups:

• age over 40;
• history of spontaneous abortion;
• intrauterine fetal death during previous pregnancies;
• the birth of a child with a history of chromosomal abnormalities;
• previous infectious and inflammatory disease during pregnancy;
• usage medicines having a teratogenic (causing congenital anomalies) effect on the fetus during gestation;
• alcohol abuse or drug use during pregnancy;
• burdened hereditary history (presence of congenital anomalies in close relatives);
• presence of blood relationship with the father.

Answers from an obstetrician-gynecologist to basic questions about the first screening:

Goals of the first screening

The main goal of screening in the first trimester is to identify the degree of risk of congenital pathology of the fetus. Using ultrasound equipment, a specialist examines “markers” of genetic diseases. Their presence indicates a high probability of chromosomal abnormalities.

Biochemical screening evaluates the amount of hormones produced by the placenta. It is called "dual" because it consists of a count of hCG and PAPP-A. Their deviation from normal values ​​indicates a high probability of congenital diseases.

Using the studies described, specialists can establish an increased risk of certain chromosomal abnormalities - Edwards syndrome, Patau syndrome, Down syndrome, de Lange syndrome, etc. Their danger lies in the fact that many children die in the first months and years after birth, because their organs have an atypical structure and cannot fully perform their functions. But if the child manages to survive, his mental and physical development will lag far behind his peers.

Attention! Both first screening examinations cannot accurately say whether the fetus has a chromosomal abnormality; these tests only reflect the risk of its presence, therefore, when bad results expectant mothers should not fall into despair - quite often the anxiety turns out to be in vain.

High risk according to the first screening is assessed by the width of the neck fold. Normally, it should not exceed 0.3 centimeters. The greater the deviation from this value, the higher the likelihood of a chromosomal abnormality.

Another marker of Down syndrome is the structure of the nasal bone. A high risk of a chromosomal abnormality is indicated by its absence at any stage of pregnancy. After 12 weeks, doctors measure the length of the nasal bone; normally it should exceed 3 mm. The shorter dimensions of this anatomical structure are a marker of chromosomal pathology.

In addition to chromosomal pathologies, screening helps in diagnosing neural tube defects. This group of diseases is characterized by abnormal formation of the brain or spinal cord, which is rarely compatible with life. Also, an ultrasound examination can reveal anomalies of other organs - absence of limbs, heart laying outside the chest cavity, hernial protrusion of the anterior abdominal wall, etc.

Preparing for the first screening

Ultrasound screening can be performed in two ways. The first of them is transvaginal - when the sensor is inserted into the vagina. With this type of ultrasound examination, a woman does not require special preparation.

The second way to conduct an ultrasound is transabdominal - when the sensor is located on the surface of the abdomen. In this case, for reliable results, the bladder must be full, so preparation for the first screening includes taking one liter of fluid an hour before the test.

To undergo the second stage of screening, in the last weeks of the 1st trimester, the expectant mother should donate blood from a vein. Material for biochemical research is collected in the morning. For reliable results a woman should not eat breakfast before the test. On the day of blood donation, only one glass of clean still water is allowed.

Three days before taking blood for biochemical analysis, a woman is recommended to exclude allergens from her diet. These include seafood, peanuts, milk, fish, chocolate. It is also undesirable to eat fried, salted, smoked foods - these foods can distort the results of the study.

To obtain reliable results, a woman needs to try to relax, since increased activity nervous system may affect the production of placental hormones. Before examinations, you should get a good night's sleep and rest. Also many experts recommend excluding sexual activity three days before the proposed screening.

Features of the event

Typically, screening in the first trimester is carried out in three stages. The first of them - preparatory - includes a survey of complaints and an examination by an obstetrician-gynecologist. The specialist collects the woman’s life and hereditary history and calculates the date of conception. For the reliability of screening results, the doctor must know the exact age of the patient, her chronic diseases, endocrine pathologies, and the presence of IVF.

Without fail, the doctor finds out whether there are hereditary diseases in the family. The specialist will also learn about the course of previous pregnancies - the presence of miscarriages, the birth of a child with congenital anomalies, etc. Expectant mothers with a family history are recommended to undergo genetic screening.

After consulting a doctor, the woman is given a referral for an ultrasound examination and biochemical analysis. The order of their implementation differs in different clinics.

Sometimes both tests are done on the same day. This most often happens if the ultrasound is done transvaginally, since you need to drink a large amount of water before a transabdominal ultrasound examination. This may skew the results of the first screening for placental hormones.

Sometimes the study is carried out in two stages. On the first day, the woman undergoes an ultrasound, which calculates the date of conception. The obtained values ​​are necessary to decipher the results of the biochemical test, since the amount of hormones changes every day.

Less often, women first donate blood for a biochemical test. With the results obtained, the expectant mother goes for an ultrasound, where the gestational age is calculated again.

Ultrasound screening

Usually ultrasound scanning fetus does not exceed 30 minutes. If the test is performed transvaginally, a disposable condom is placed over the sensor and then inserted into the vagina. If performed correctly, a pregnant woman should not experience discomfort.

During transabdominal ultrasound, the anterior wall of the expectant mother's abdomen is lubricated with a special gel. The sensor of the device will slide over it, the image is shown on the monitor. Such research also does not cause discomfort in a pregnant woman.

Many women ask to determine the sex of the child at the first screening. Some doctors may try to look at the fetal pelvic area. However, for accurate results, the baby should be facing the anterior uterine wall.

The longer the pregnancy, the higher the likelihood of correctly determining the sex of the child. At week 11, the number of successful attempts does not exceed 50%. At the end of the 13th week, in 80% of cases, the doctor can determine the sex of the baby.

To carry out ultrasound screening, certain conditions must be met. The first of them is the length of the fetus from the coccyx to the crown of the head is at least 4.5 centimeters. Second - unborn child should take the desired position in the uterine cavity. To do this, the doctor may ask the woman to move around or cough.

During an ultrasound examination, the doctor evaluates the following basic parameters:

• KTR - length of the fetus from the end of the spine to the crown;
• skull circumference;
• BPR - length of the space between the parietal tuberosities;
• TVP - thickness of the collar space (neck fold);
• pulse;
• length of limb bones;
• presence, position, structure of internal organs;
• anatomical structure of the placenta;
• the presence and structure of the nasal bone.

First screening standards:

Gestational age

Nasal bone, mm

Pulse, beats/min

If indicated or at the request of the pregnant woman, the doctor can conduct additional research using a Doppler sensor. This test shows the state of blood exchange between the vessels of the uterus and placenta; pathologies indicate oxygen starvation of the fetus. Also, Doppler ultrasound allows you to see the number of vessels in the umbilical cord - normally there should be two arteries and one vein.

Biochemical screening

To assess the amount of hormones produced by the placenta, specialists draw blood from a vein. This procedure is practically painless; if you are afraid, you should not look at the syringe. First, the laboratory assistant applies a tourniquet to the shoulder, then the woman needs to clench her fist several times. After the described manipulations, the specialist inserts a needle into the vein and takes a few milliliters of blood.

Screening evaluates the number human chorionic gonadotropin person. This hormone is produced by the placenta, its amount in the blood increases until the 11th week, then it decreases slightly. Many chromosomal and placental abnormalities are accompanied by changes in the amount of hCG.