The diagnostic procedure performed on pregnant women is called perinatal screening. It is done in order to determine whether a woman has abnormal fetal development or whether there is a deviation from the norm. The attending physician decides how many times to do perinatal screening.
This research includes:

1. Ultrasound of fetal development during pregnancy.
2. Biochemical tests for blood tests.

Of course, biochemical screening in the 2nd trimester will not help determine the risk of pathologies and will not protect against violations of the norm. To obtain accurate results, additional invasive diagnostics are required.

Up to 14 weeks - 1st trimester. A double trimester pregnancy test is done.
When the period is 20 weeks or more - 2nd trimester screening. A triple test is done in the second trimester, doctors look and determine the dynamics of pregnancy and compare it with the norm.
After 30 weeks, screening is a complex of studies and an integral test is performed.

In principle, if normal results are obtained, it is enough to do three ultrasounds. However, you need to understand well that every woman’s body is individual, therefore, how many ultrasounds are needed is determined by the gynecologist.

Is it necessary to do a second screening?

One of the arguments for not carrying out screening diagnostics is the fear of obtaining accurate information about the formation of the child, or finding out information about deviations from the norm. Sometimes the results of such diagnostics turn out to be false and show incorrect deviations from the norm. This will definitely cause anxiety in the mother, which can negatively affect the health of the unborn baby.
That is why the woman decides to do the second screening on her own.

If a pregnant woman’s indicators are all normal and there are no abnormalities, it is enough to do one ultrasound. It is better for her not to undergo invasive diagnostics.

Data from the results of repeated screening may show deviations from existing norms in fetal development. A child may be born with severe pathology. The results of such screening have an impact on the woman’s psyche. Taking this into account, second screening has been prohibited in Russia for two years now.

What diseases can be diagnosed in the fetus?

Conducting a second trimester screening allows doctors to diagnose the likelihood of several diseases in the fetus:

• Down's disease
• Edwards syndrome
• Neural tube disorders

Indications for conducting a second trimester screening study are:

1. When a woman is over 35 years old.
2. There is a threat of miscarriage.
3. There is already a child with congenital abnormalities.
4. A woman needs to take medication that is contraindicated during pregnancy.
5. When the first screening revealed a risk of pathological changes in the fetus.

To conduct the second screening, special preparation for the ultrasound is required, for example, you will have to drink a glass of water.

Fetometric indicators

Standard fetometric indicators of normal fetal development are:

• Biparietal size – BPR. The diameter of the fetal head is determined
• Fronto-occipital data – LZR
• Head circumference - OG
• The size of the tummy and its roundness - OJ
• Size of long bones

The results obtained enable the doctor to determine the gestational age. In addition, doctors look at the anatomical structure internal organs baby to detect the occurrence of congenital defects or deviations from the standard norm.

What tests are required for the second screening?

To undergo the second screening, the doctor gives a referral for mandatory tests:

1. Biochemical screening or triple test. The protein level is determined - hCG, AFP, estriol. A more detailed explanation of these meanings is given at the end of the article.
2. Ultrasound. At week 20, this examination may detect deviations that do not correspond to the norm. Later this will become impossible. The specialist will determine whether the size of the fetus corresponds to the gestational age and whether its development is proceeding correctly.

In addition, several additional analyzes are carried out:

1. Study underway amniotic fluid.
2. Fetal blood is studied. Cordocentesis is performed, in which blood is taken from the umbilical cord.
3. When a woman suffers chronic diseases, additional research is being conducted.

Preparing for the study

In principle, no special preparation is required for the second screening. Before diagnosis, you need to follow a certain diet:

• You can eat food three hours before the start of screening
• Products should not contain a lot of fat and cholesterol
• It is forbidden to drink carbonated drinks
• do not eat seafood
• do not drink cocoa and coffee

Of course, if there is a desire to have a snack, a pregnant woman does not need to completely refuse this. When the second screening is done, the woman may not follow a strict diet. Only the first screening requires following a strict diet.

The second screening does not require that the bladder be completely full. During this period, the level of amniotic fluid is quite sufficient for the study.

The state of the gastrointestinal tract does not have any effect on ultrasound diagnostics. Under pressure from the uterus, during this period the intestines moved back. Still, doctors, in order to get the most accurate results, advise women not to use the above products 24 hours before the procedure.

It must be said that screening the second trimester during pregnancy opens up the opportunity to identify a risk group. It shows existing pathologies. However, preparation for this study, regardless of trimester, remains the same and unchanged.

The main task of a pregnant woman is to eliminate anxiety and maintain normal psychological state, the desire to get a positive result.

Diagnostic technique

Such a study after 20 weeks can also occur in the presence of the husband of the expectant mother. To perform an ultrasound, the abdominal method is used. The patient should lie on her back; you can use a couch, placing a cushion under her right side.

The stomach should be open to the pubis. The sensor is installed on its front part, pre-lubricated with gel.

When conducting a study, after week 20, the sonologist changes the location of the ultrasound transducer. The woman does not feel any discomfort. The child moves much more actively at this time.

Triple test

At the 20th week of pregnancy, every woman seen at the antenatal clinic must do a “triple test”. Carrying out such a procedure involves a blood test taken early in the morning on an empty stomach. Several indicators are determined.

HCG level

Stands for human chorionic gonadotropin and belongs to a group of hormones. It has several properties:

1. Does not allow the corpus luteum to disappear during pregnancy. This hormone increases estrogen synthesis at the beginning of pregnancy.
2. He is engaged in changing the anatomical structure of the expectant mother’s body.
3. Prevents the rejection of fetal cells by the maternal immune system.
4. Stimulates the sex glands.
5. Strengthens the work of the fetal adrenal glands.

What is AFP (alpha fetoprotein)

The protein, or alpha-fetoprotein, is produced in the liver and gastrointestinal tract of the fetus. It transports nutrients to the emerging fetus. Protects the embryo from immune system mother. Prevents fetal rejection. The concentration of AFP during pregnancy constantly increases in the blood of the mother and the unborn child.

Free estriol

Estrogen hormone is produced in the female body in small quantities.

After pregnancy, the role of free estriol increases sharply. Under its influence, the uterus prepares to feed the fetus and its future growth. The milk ducts are prepared and opened to allow for future breast-feeding baby.

These three indicators enable specialists to determine whether the child has developmental pathologies at the 20th week of pregnancy and whether everything is normal. As a result, it will be possible to understand whether the baby has a heart defect, Down syndrome, or other developmental pathologies.

It must be said that sometimes even “negative” results triple test They don’t always say for sure that the fetus is developing incorrectly.

When a second ultrasound is performed during pregnancy, the doctor differentiates the sex of the unborn baby. This perinatal screening, otherwise comprehensive examination, is planned, and is carried out to identify possible pathologies The child has. In obstetrics, official dates are defined, but they can be changed by the decision of the obstetrician-gynecologist leading the pregnancy if the doctor has doubts about the positive dynamics of embryo development.

Time range for second screening

During pregnancy, the condition of the woman and fetus should be monitored using screening three times. In the first, 2nd trimester, and third, respectively. All examinations are important for a woman and child. The need for a second screening during pregnancy is due to the possibility of preventing various pathologies in the future, or identifying existing ones. During this period, the doctor can already examine the unborn baby in detail and assess the degree of development of its internal organs.

As for the timing of the 2nd planned ultrasound, usually the time range from the 20th to the 23rd week is selected. These are general indicators. The doctor should decide exactly at what time to do the second ultrasound during pregnancy, based on the patient’s individual indicators. If the doctor has any doubts, the examination may be carried out earlier.

In addition to the ultrasound procedure, a woman must undergo hormonal blood biochemistry. Medical experts advise doing this before an ultrasound examination. The results of biochemical analysis are extremely important for a deeper assessment of the condition of the mother and fetus. The list of essential hormones, the level of which will tell the doctor about possible problems, includes:

• Alphatoprotein (AFP protein). Provides the child with nutrients.
• Human chorionic gonadotropin (hCG). The so-called pregnancy hormone is responsible for preserving the fetus. It is produced from the second trimester, and its quantity gradually increases.
• Free estriol (E3). Female sex hormone. Affects the condition and development of the uterus and uteroplacental blood circulation. An increase in this hormone indicates an unhealthy condition of the mother (inflammation and infection of the liver and kidneys).

Special indications

There is a so-called risk group - pregnant women with any abnormalities. For such women, screening is mandatory if indicated. These include:

• late pregnancy(women aged 35+);
• genetic abnormalities in expectant mothers and fathers, or their older children;
• repeated spontaneous termination of previous pregnancies (miscarriages);
• a woman’s stay in the radiation zone;
• abnormal fetal development identified during previous ultrasound examinations.

Preliminary preparation for screening, regardless of how many weeks it is carried out, is not necessary.

Second trimester ultrasound screening is a desirable stage of pregnancy

Assessment of organs and systems during repeated ultrasound

During the second screening during pregnancy, the gynecologist evaluates the health status of the woman and baby. U expectant mother studied:

• the main organ connecting the embryo and mother (placenta). The location, thickness and structure of the “children's place” are subject to analysis;
• the living environment where fetal development occurs (amniotic fluid). Their number is estimated;
• umbilical cord vessels. The emphasis is also on quantity;
• female reproductive organs (uterus with appendages and cervix).

The vital activity of the embryo depends on the state of health of the mother’s body, at any stage of pregnancy. The second planned ultrasound during pregnancy helps to collect maximum data on the child’s health status, identify and assess the degree of deviation from the norm for a given period of development.

The following parameters are analyzed:

• the location of the fetus itself in the womb;
• bony frame of the head and facial bones;
• the main rod of the entire skeleton (vertebral column);
• maturity of the bronchopulmonary system;
• degree of heart development;
• state of brain structures;
• genitourinary and digestive systems;
• general compliance with developmental norms (fetometry).

In addition, ultrasound in the second trimester can show possible external genetic abnormalities (improper development of legs, arms, fingers). During the second ultrasound during pregnancy, the doctor determines the following dimensional indicators in the child: head and abdominal circumference, length of the thigh and lower leg bones, length of the humerus and forearm bones, fronto-occipital size of the fetus.

The woman receives the diagnostic results in her hands on the same day

The correct dimensions of good intrauterine development, which are shown by the second screening ultrasound performed at the twentieth week of pregnancy, are:

• head and abdominal circumference: 154–186 mm and 124–164 mm, respectively;
• fronto-occipital size: 56–68 mm;
• length of the femur and tibia bones: 29–37 mm and 26–34 mm;
• length of humerus and forearm: 26–34 mm and 22–29 mm.

Hormonal tests determine the abnormal development of the nervous system, heart, esophagus, umbilical hernia, the risk of miscarriage in the mother. In addition, tests of the expectant mother and ultrasound examination the second trimester will show more serious abnormalities. During the second screening, a medical specialist can identify the presence of the most severe defect of the nervous system, anencephaly, a serious form of genomic pathology - Down syndrome and chromosomal pathology trisomy 18 syndrome, known as Edwards syndrome. As well as rare genetic diseases Turner syndrome and Patau syndrome.

Screening results are assessed only as a whole. If abnormal development of the child is detected during an ultrasound, it is better for the woman to go to the hospital, where many additional tests are performed. In particular, amniocentesis. This is a complex procedure for collecting amniotic fluid for analysis. The operation is risky, but the accuracy of the results is more than 95%.

The doctor should give the necessary recommendations. Perhaps the question of terminating the pregnancy will arise. After a period of more than 22 weeks, a medical abortion is no longer possible, and the method of artificial childbirth causes both physical pain and psychological suffering to the woman. The decision, in any case, depends on the woman.

Factors influencing results

When screening is done, there may be some errors in the results. This may depend on the condition of the equipment and the qualifications of the medical specialist. Also, there is the influence of other factors:

• age-related changes woman’s body (age 35+);
• unhealthy antisocial lifestyle (drugs, alcohol, nicotine). These reasons make pregnancy initially complicated;
• hormonal dependence. The expectant mother has diseases, the treatment of which requires constant use of hormone-containing drugs;
• chronic pathologies during exacerbation;
• body mass. In obesity, blood counts are always elevated. Lack of weight, on the contrary, reduces performance;
• non-natural fertilization (IVF);
• the child is too big;
• multi-embryonic pregnancy (twins, triplets, etc.).

Second trimester screening can determine the presence of pathologies in the fetus

If fetal pathologies are detected, you should not panic; you need to do an ultrasound again. Change the clinic or specialist, wait for remission of the disease, and perform an amniocentesis procedure.

Ultrasound of the 2nd trimester is an extremely important procedure during the period of bearing a baby. The results provide a prognosis for the further course of pregnancy and the stage of health of the unborn newborn. Constant monitoring by a doctor in time will prevent possible complications, and with the correct course of pregnancy it will provide peace of mind to the woman.

Find out how it grows and develops unborn child, allows 2nd trimester screening. Is it necessary to undergo the procedure, since it is considered much simpler than the first screening? Who is the examination indicated for, and in how many weeks is it carried out? What does a woman need to know about diagnosis?

For what period is it carried out?

Such testing (screening) for expectant mothers began relatively recently, since 2000. It includes an ultrasound examination and a biochemical analysis taken from a vein. The first time a pregnant woman is examined is from 10 to 13 weeks, the second screening is carried out from 16 to 20 weeks. The time frame for more informative and accurate tests required for the second screening is from 16 weeks to the 6th day of the 18th week. By ultrasound - from 19 to 22 weeks.

If the pregnant woman’s blood did not raise suspicions during the first examination, then at the 2nd screening the doctor recommends undergoing only ultrasound diagnostics. The third ultrasound is done from 22 to 24 weeks, and it is mandatory. Although, if she wishes, the expectant mother can donate blood again and get tested in any laboratory at her own expense.

What does screening show in the second trimester?

When attending an ultrasound, the expectant mother can count on the following information:

• condition of the placenta,
• are there any pathologies in the cervix and appendages;
• amount of amniotic fluid;
• position of the fetus in the womb;
• dimensions of the fetus (volume of the chest, abdomen, head, length of the spinal column and limbs);
• how the main organ of the nervous system – the brain and spinal cord – develops;
• how the facial bones, eyes, nose are developed;
• state of the cardiac and vascular system;
• Are the internal organs developing correctly?

A second screening is mandatory for women at risk:

• parents who are relatives;
• those who have had an infectious disease during pregnancy;
• parents with a genetic disease in their family;
• if the woman has had cases of stillbirth and spontaneous abortion;
• if the family has children with mental, nervous, or genetic pathologies;
• when any disorder is detected at the first screening.

How to properly prepare for research

After the first test, it is unlikely that a second screening during pregnancy will be an unexpected procedure.

You need to prepare for it, just like the first time:

• the day before donating blood, you must refrain from eating fatty, spicy, fried foods;
• donate blood on an empty stomach, and drink water only if you are very thirsty;
• avoid stress and anxiety, which can negatively affect results.

Ultrasound is performed without special preparation. It has no contraindications, is painless and non-invasive. Ultrasound diagnostics of prenatal screening is considered a modern, highly informative and safe method that allows you to examine the condition of the mother and child.

A pregnant woman lies down on the couch. The doctor smears the stomach with gel and conducts an examination with a special sensor through the skin. The patient receives the transcript and results within a few minutes.

What does 2nd screening include?

The second screening shows the presence or absence of risks of having a child with chromosomal defects. The main task of prenatal screening is to identify mothers who are at risk of giving birth to a baby with abnormalities and to examine them more thoroughly, for example, invasively. Based on the results of an in-depth examination, treatment will be prescribed or artificial termination of pregnancy will be proposed.

The second screening is called triple screening, as it includes 3 indicators:

• Alpha fetoprotein (or ACE) This is a protein produced by the liver and gastrointestinal tract of the embryo from the 3rd week. It is responsible for transporting nutrients and protecting the fetus from estrogens produced by the mother's body for its own protection.
• Chorionic gonadotropin (CG)– a hormone actively synthesized by chorion tissues after embryonic implantation. It is considered an important indicator of a healthy pregnancy, regulating female hormones. The 1st screening is characterized by studying the level of the β-subunit of hCG, since by week 10 its amount increases to the maximum, and then gradually decreases. During the second screening period, β-subunits and hCG are equally studied.
• Free estriol- a hormone synthesized by the baby’s liver and adrenal glands. It affects the condition of the uterus, placental circulation and the functioning of the woman’s mammary glands.

In modern laboratories, a pregnant woman can undergo an additional analysis that reveals the amount of inhibin A. This is a female hormone, the levels of which depend on the timing of pregnancy and the general condition of the fetus.

Normal indicators by week and interpretation

When interpreting tests done during screening, take into account external factors weight, height of the pregnant patient, her bad habits.

Standards for biochemical analysis

Many patients carrying a child are interested in what they look at on an ultrasound and at what time it is best to conduct it. Experts believe that ultrasound diagnostics It's better to do it before 22 weeks. If there are indications for termination of pregnancy, then medical abortion is not performed after 23 weeks. Then the pregnancy is terminated by artificial birth.

Ultrasound standards

If prenatal screening data meets standard standards, then the possibility of having a healthy child is extremely high. But there is also a small percentage of error in which even not entirely reassuring results indicate the presence of some kind of disorder. There are a number of factors that directly affect the results (this applies to biochemical analysis):

• obesity, diabetes Mom;
• multiple births;
• addictions (alcoholism, smoking, drug addiction);
• conception using IVF method.

Deviations from established standards

If factors that negatively affect screening are not identified, then overestimated or underestimated values ​​may indicate some defects in fetal development.

Only the doctor deciphers the results of prenatal screening and explains to the patient her further actions.

At approximately 19-20 weeks of pregnancy, each expectant mother needs to undergo a second screening (2 trimesters) and an ultrasound. These dates were not chosen by chance: this is the most convenient time to study hormones.

You already remember, I was in the middle of the 1st trimester.

Usually it shows that everything is fine.

After all, at that moment it is possible to determine with accuracy only whether the fetus is developing correctly or not. It is not easy to understand deviations from the norm at such a time.

But the screening results can tell a lot.

So, what does the second examination show and look at?

What it includes: basic tests

Screening is from the English “viewing”. That is, identifying a risk group that may have children with certain diseases.

Probabilities can be calculated according to different principles. The most famous program is PRISCA (Prenatal RISk Assessment) - perinatal risk assessment.

The standard timing for the second screening is from 16 to 20 weeks.

The later all the examinations are carried out, the more accurate the results will be. But it is also more dangerous to have an abortion.

Therefore, the optimal time for examination is 17-19 weeks.

The doctor will refer you to:

• Biochemical screening of the 2nd trimester.
  • It's a triple test.
  • Here, blood will be taken from a vein and three components (AFP, hCG, estriol) of the blood will be checked for the presence of special markers.
  • Based on the tests, it will be clear what the risk of developing diseases such as Down syndrome and Edwards syndrome is.
  • This type of research is completely safe, because there is no effect on the mother's body. They're just studying blood.

• . More accurate than usual.
  • It can be used to identify disorders such as heart defects, cleft upper lip or palate, diaphragmatic hernia, shortened bones, clubfoot, crossed toes, etc.
  • There may be minor defects that can be cured with time, medication or surgery, and serious defects that will remain with the child for life.

• Cordocentesis.
  • It is not a mandatory part of routine screening.
  • But if an ultrasound or examination reveals any abnormalities, the procedure is advisable.
  • Using a special needle, fetal blood will be taken from the umbilical cord to conduct more detailed examinations and obtain more accurate results.
  • The method is not completely safe. But according to statistics, in 2% of cases after the procedure.
  • Often there are various hematomas and bleedings after the injection, which go away quite quickly.
  • In 1 case out of 100, an infection is introduced into the blood.

Often, PRISCA includes examinations such as calculating the cervical transparency (calculated through ultrasound), measuring the coccygeal-parietal size, and many others.

Forecast of possible diseases

Most often, perinatal screening in the 2nd trimester is carried out to find out whether the child has certain diseases during pregnancy.

Down syndrome

The disease appears at the moment of chromosome crossing immediately after conception.

Otherwise, the disease is called trisomy 21, i.e. The 21st pair of chromosomes is not a pair, but a triple.

This occurs because the sperm or egg at the time of conception had one extra chromosome 21. The probability is approximately 1-1.5%.

It is impossible to predict the onset of illness in a child. Does not depend on the woman and the father of the child. Maternal age has only a slight effect on the likelihood of the syndrome.

Neural tube defect

The neural tube is formed in the embryo around the 20th day of pregnancy in the form of a plate.

After a few more days it should curl up into a tube.

These deadlines are not very long, so the process goes almost unnoticed.

The problem is this: it may not close completely or may unfold further, which may result in spinal defects.

Unfortunately, it is impossible to immediately determine the violation on early stages difficult.

By the middle of the 2nd trimester, namely by the time of screening, the defect will be revealed by ultrasound.

The result of the disorder can be spinal clefts, hernia and other neurological defects. The second biochemical screening allows you to notice such troubles.

Edwards syndrome

The causes of the disease are similar to Down syndrome.

Only here does trisomy 18 occur. Such children are born late, but look like premature babies.

They are small, light, painful and weak.

Numerous defects of internal organs and body parts, which can also be seen on ultrasound. Such a child will not live long: it is a rare baby who lives to see his first birthday.

Fortunately, this syndrome is extremely rare: in 1 case out of 5000. But the probability still exists.

Screening results

The screening examination must take place on the same day.

A biochemical study in the 2nd trimester will show the level of three elements. What is the interpretation of the results?

A protein that is produced by the fetus itself, and not by the mother’s body, during pregnancy.

During the examination, its percentage is accurately calculated. It enters a woman's blood in certain quantities.

Any deviation from the norm means some kind of deviation in the development of the fetus.

According to PRISCA, at 15-19 weeks of pregnancy the level should be approximately 15-95 units/ml.

Results above normal probably mean a disorder in the development of the spinal cord, a neural tube defect.

If the ACE level is much lower than normal, Down syndrome, Edwards syndrome, Meckel syndrome, nuchal hernia, liver necrosis, spina bifida are possible.

• Estriol

A hormone produced by the placenta. And starting from the second trimester, it is produced by the fetus itself.

At the same time, its level should constantly increase. At 17-18 weeks the norm is 7-25. At 19-20 – 7.5-28.

If the level is lower than it should be, Down syndrome and premature birth are possible.

Human chorionic gonadotropin.

According to PRISCA, increased level talks about chromosomal pathologies like Down syndrome and Edwards syndrome.

Advice: it’s best not to try to interpret the results of an examination or ultrasound on your own.

Without medical education there is a high probability of getting confused - decoding is not so simple. And the doctor will describe everything to you clearly and in detail.

If the results of the second screening are not very good, do not rush to get upset: you will be prescribed additional examinations, where the condition of the fetus will be determined with greater accuracy.

Is screening worth it?

Of course, this examination is not mandatory. Moreover, it is often paid.

And the results of the study are not always confirmed after the birth of the child.

Pregnancy is not only a joyful time of waiting for a baby, but also a lot of worries associated with possible diseases and disorders. If the results of the first ultrasound and blood test were controversial or showed the presence of pathology, screening in the 2nd trimester can more accurately confirm or refute the diagnosis.

Second screening during pregnancy

A set of examinations carried out during pregnancy makes it possible to determine the condition of the growing fetus, the presence or absence of serious deviations in its development. Several times during the period of bearing a child, a woman undergoes screening, consisting of an ultrasound ( ultrasound examination) and biochemical blood test.

The need for examination

• genetic diseases in close relatives;
• parents' age over 35 years;
• dangerous viral diseases suffered in the first trimester;
• history of miscarriages and frozen pregnancies;
• close relationship between parents;
• alcohol and drug addiction;
• use of drugs with teratogenic effects;
• pathologies identified during the first screening;
• radiation exposure before pregnancy in either parent;
• maternal cancers;
• threat of miscarriage.

Pathologies that can be identified through screening

Second trimester screening is informative and accurate test to identify the following deviations:

• Down syndrome is a congenital genetic disease characterized by an increase in the number of chromosomes. Patients have trisomy 21, reduced intelligence, various developmental defects, but at the same time a fairly long life expectancy;
• Patau syndrome is a disease in which a person has an extra 13th chromosome. Characterized by high mortality (children are born practically non-viable and most of them die in infancy);
• Meckel's syndrome is a genetic mutation in which after birth there are many serious disorders incompatible with life;
• Edwards syndrome - diagnosed when there is an extra 18th chromosome. Such children suffer from profound mental retardation and rarely survive beyond 1 year of age;
• delayed internal development of the child;
• frozen pregnancy;
• risk premature birth;
• defects in neural tube maturation.

Screening results allow parents to decide to terminate a pregnancy if serious abnormalities or genetic abnormalities are detected in the development of the fetus. However, you need to know that there is always a chance of giving birth to a healthy baby.

Preparing for screening

Before conducting research you must:

• give up chocolate, fried and fatty foods, citrus and potentially allergenic products;
• Do not eat in the morning before the examination, since blood is donated on an empty stomach.

How many weeks do 2 screenings take place?

Usually the second screening is carried out from 15 to 20 weeks. As the gestational age increases, the accuracy of the study increases, so it is more often prescribed starting from the 17th week.

The screening test is absolutely safe for mother and child.

What factors may influence the results?

Despite the greater accuracy of measurements, there is always the possibility of influence of extraneous factors on the examination results. These include:

• diabetes in a pregnant woman (leads to a decrease in the level of the hormone hCG (human chorionic gonadotropin), which begins to be produced in the body after conception);
• smoking, drinking alcohol and drugs;
• small or overweight mother (the height and body weight of the fetus may be reduced or increased relative to the norm);
• in vitro fertilization (increased biochemical blood test values);
• multiple pregnancy(high levels of hormones, difficulties in measuring each child individually).

If pathologies are suspected and to clarify the diagnosis, additional studies are carried out:

• amniocentesis - sampling of amniotic fluid (amniotic fluid) through the anterior abdominal wall of the mother;
• cordocentesis - the study of umbilical cord blood, which is taken through a puncture;
• Ultrasound with Dopplerography is a type of ultrasound examination that examines the condition of the fetal vessels and maternal organs.

Carrying out an ultrasound

The second ultrasound is performed through the surface of the mother’s abdomen, so it is easily and comfortably tolerated. During the procedure, the doctor examines:

• the size of the fetus and its compliance with standards (fetometric indicators);
• structure of the face, brain, cerebellum, heart, stomach, liver, kidneys;
• skeletal system;
• position (presentation) of the child;
• condition of the mother's pelvic organs;
• homogeneity of the placenta, amniotic fluid level, umbilical cord.

Ultrasound as part of prenatal genetic screening - video

Fetal fetometry

Determining the length of the bones, the volume of the skull and torso are very important for understanding whether the child is developing normally. In addition to size, the doctor evaluates the presence of all bones - there are congenital diseases in which the entire phalanges of the fingers, hands, arms and legs may be absent. At this stage, you can see hip dysplasia in the baby (in this case, it may be recommended to abandon natural childbirth in order to avoid serious damage to the newborn).

Average fetal size values ​​by week are within normal limits - table

Examination of the brain, face and internal organs

In addition to fetometric indicators, the brain, the structure of internal organs and the face are examined in detail.

Areas of fetal examination - table

Mother's provisional organs

Provisional organs are temporarily formed in a woman during pregnancy. This is the placenta, umbilical cord, and amniotic fluid. The health of the baby largely depends on their condition. The following indicators are studied:

• location of the placenta (place of its attachment relative to the cervical os);
• thickness of the placenta (if it is higher than normal, intrauterine infection may occur);
• homogeneity of the placenta (otherwise its early aging may occur);
• the number of umbilical cord vessels (normally this is one vein and two arteries, which eliminates the possibility of fetal hypoxia);
• volume of amniotic fluid (detects high or low water levels);
• the tone of the uterus, its size, the presence of tumors, the length of the cervix (normally the cervical canal should be about 2 cm. If it is shortened, the risk of premature birth increases even in the second trimester).

Interpretation of the results of a biochemical blood test during 2nd trimester screening

To assess the child's health, three blood components are examined: free estriol, human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP). Analysis of the levels of hormones and proteins makes it possible to make a preliminary diagnosis; full conclusions are drawn only after a comprehensive study of the screening results.

When testing blood, there is a possibility of misdiagnosis. About 10% of results are false positive, and the level of undetected pathologies reaches 30%. The analysis gives a fairly high detection rate of Down and Edwards syndromes - 70%, anomalies in the formation of the neural tube - up to 90%.

Changes in the level of estriol, hCG and ACE in various pathologies - table

HCG norms by week of pregnancy

Deviation from the norm hCG level may be a symptom of various chromosomal abnormalities.

Normal hCG values ​​- table

AFP norms by week of pregnancy

AFP - alpha-fetoprotein, synthesized yolk sac and fetal liver cells. This protein performs functions without which the normal formation of a child is impossible: it protects against the mother’s immune cells, and participates in lipid and protein transport.

ACE values ​​are normal - table

An increase in AFP levels may indicate the following diagnoses:

• multiple pregnancy;
• large fruit;
• viral damage to the fetal liver;
• abnormalities in the development of the neural tube;
• improper fusion of the anterior abdominal wall;
• Shereshevsky-Turner syndrome (a chromosomal disorder that results in abnormalities physical development, sexual infantilism and short stature).

A low AFP level may be a symptom of:

• Down syndrome;
• Edwards syndrome;
• threats of premature birth;
• frozen pregnancy;
• delays in fetal development.

Norms of free estriol by week of pregnancy

At this stage of the examination, the liver and adrenal glands of the fetus are responsible for the production of estriol. The functions of the hormone are varied:

• participates in the process of uterine growth during pregnancy, improves blood flow;
• accelerates the accumulation of glycogen and adenosine triphosphates;
• stimulates the preparation of the mammary glands for future lactation;
• activates enzyme mechanisms.

Normal free estriol values ​​- table

Usually, an elevated level of estriol does not indicate any serious violations. The reasons may be the large size of the fetus, multiple pregnancies, or liver disease in the woman. A low level is an alarming symptom of Down syndrome, adrenal underdevelopment, viral internal infection, and the risk of early birth.

Routine ultrasound - video