How to pass first trimester screening. What is needed for the first screening? Factors that accompany false results include:

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 to infectious diseases during pregnancy;
• 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;
• for any reason, took 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 the intrauterine development of the unborn child is at risk.

According to medical observations, the numerical designation of the coccygeal-parietal size increases as the gestational age increases. 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 are pathological processes in the baby’s body, they will be detected 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 enters a new stage of 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, ultrasound diagnostics did not detect such dangerous phenomena as fetal deformation or complete absence of a heartbeat, 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 deviations. 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, the 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, the cells of a woman’s immune system, 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 a disease during the first screening during 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 is monitored with special attention by a specialist conducting 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.

Non-invasive comprehensive examinations, which are carried out two or three times during pregnancy, are called prenatal screening. It is necessary to assess the condition of the expectant mother and child: according to statistics, prenatal diagnostics can detect more than 98% of defects at the stage of intrauterine development of the fetus, and in many cases the pathology can be eliminated. The first screening during pregnancy is carried out at 10-14 weeks; its necessity and the exact date are determined by the doctor.

What does the first trimester screening test consist of and what does it show?

The first perinatal screening includes ultrasound and a comprehensive study of venous blood.

Ultrasound for the first screening can be performed abdominally (the sensor is moved along the outer wall of the peritoneum) or transvaginally (the sensor is inserted into the vagina). During the examination, the doctor determines the number of embryos and their location, the type of placenta previa, and assesses whether the fetal organs are located correctly. He also determines the baby's heart rate and takes fetometric measurements of his body:

• width of the neck fold,
• dimensions of the head (fronto-occipital and biparietal) and the length of its circumference,
• chest diameter and abdominal circumference,
• thigh length.

• age over 35 years;
• the presence of hereditary diseases or genetic abnormalities in the family;
• viral diseases suffered during this pregnancy;
• cases of miscarriages or frozen pregnancies, stillbirths;
• cases of birth of children with genetic pathologies;
• use of prohibited medications, drugs or alcohol during pregnancy;
• close relationship between the mother and the child's father.

During the first perinatal screening, a biochemical blood test determines the content of two specific placental proteins. These are human chorionic gonadotropin, the main hormone of pregnancy, and protein A, the content of which increases with increasing pregnancy.

A drop in human chorionic gonadotropin levels may indicate placental pathologies that create a risk of miscarriage; an upward deviation of this indicator indicates a multiple pregnancy or chromosomal abnormalities.

The plasma protein test allows you to determine the risk of a child developing congenital defects; in the presence of the most dangerous of them, the level of protein A in the blood of a pregnant woman is significantly reduced.

Thus, screening makes it possible to detect early signs of serious fetal anomalies, such as de Lange, Down, Patau, Smith-Opitz, Edwards syndromes, umbilical hernia and triploidy (the presence of a triple set of chromosomes instead of a double one).

How are screening results interpreted?

Ultrasound and blood test data are presented in the form of tables. Then the information is processed using special programs, while additional indicators are entered into the computer - the age of the pregnant woman, her weight, the presence of concomitant diseases, ethnicity and others. If all the indicators obtained during the study correspond to the norm, the test result is considered negative.

Normal indicators of the first screening during pregnancy are:

As can be seen from the table, some indicators of the norms calculated for a 10 and 13 week fetus differ slightly, or their acceptable ranges overlap each other.

In case of deviation from the norm, the program compiles estimated ratios that reflect the likelihood of a child developing a particular pathology. For example, a ratio of 1:50 means that out of 50 women who have the same screening test results, only one will have a child with this pathology, the rest of the women will have healthy children. The higher the second number in the estimated ratio, the lower the risk.

That is, an indicator that does not correspond to the norm is not yet a fact of the presence of an anomaly in the child, it only serves as a reason for more careful monitoring of the course of pregnancy. If the risk level is assessed as high, the pregnant woman is referred for consultation to specialized specialists and, if necessary, additional diagnostic examinations are prescribed.

How to properly prepare for your first screening test

First of all, it should be borne in mind that stress or severe fatigue experienced on the eve of the test can distort the test results. Therefore, doctors recommend avoiding significant physical activity, anxiety and negative emotions the day before the examination.

Usually the first stage of screening is ultrasound. If it is performed transvaginally, no preparation is required. During an abdominal (external) examination, the bladder should be full, so before starting the procedure you should drink 1.5 - 2 liters of still water.

Biochemical screening (blood test from a vein) is performed on an empty stomach; food should not be consumed for at least 4 hours before blood sampling. In order for the test results to be as reliable as possible, 2 days before the test you need to exclude fatty and fried foods, meat, seafood, citrus fruits, and chocolate from your diet.

Ultrasound is also screening, the most accurate diagnosis of pregnancy and monitoring its development. Every pregnant girl experiences slight jitters before an ultrasound. Especially before the first session. What is this fear associated with? You want to be sure that everything is fine with the baby, he is developing within normal limits, also add to this the excitement before the “first meeting”. In addition to the fact that you need to calm down in this situation, preparation before the first ultrasound procedure is also important. What do you need to prepare for there, you ask? Read on and you will understand everything.

The doctor usually prescribes the first screening at 10-14 weeks of pregnancy. However, feeling impatient, expectant mothers often run to the antenatal clinic themselves as soon as they see two lines to make sure that pregnancy has really occurred.

During pregnancy, it is harmful to be nervous and be around people who smoke. And doing an ultrasound is absolutely not harmful. It is harmful not to do screening: refusal of the first test leads to the fact that every year 100 thousand children with Down syndrome are born in Moscow alone. The disaster can be prevented. Although not everyone finds this method ethical, voluntarily giving birth to a child with disabilities is also not ethical for everyone.

Many studies have been and are still being conducted on the topic of the harm or benefit of ultrasound examination, but no one has been able to prove its harm to the influence of the fetus. Naturally, this does not mean that ultrasound should be done every week, but the mandatory three examination procedures must be completed.

Immediately after a delay has occurred, you should not go for an ultrasound examination - for such a short period of time, not even the most powerful and modern ultrasound machine will be able to show you anything useful. If you doubt whether pregnancy has really occurred or the body has decided to joke, in addition to a pregnancy test purchased at a pharmacy, you can take a blood test for hCG in the laboratory for your GI tract.

Why do you need to do an ultrasound at a short period of time?

The purpose of screening diagnostics in early pregnancy is:

• Establishing the exact date of pregnancy.
• Determination of the uterine localization of the fertilized egg.
• Diagnosis of possible complications.
• Assessment of the vital activity of the embryo.
• Study of the structure and size of the fertilized egg and embryo.

How to prepare for your first screening

1. Before the session, it is advisable to drink two glasses of mineral (not carbonated!) water 2 hours before, because as a rule, the first screening is done transabdominally (from the outside). If this information is not enough for the doctor to make a diagnosis, an ultrasound will be performed transvaginally (from the inside), and you will be asked to empty your bladder before this.
2. For the procedure itself, you need to take with you a large towel or diaper, shoe covers, a condom for ultrasound, yes, yes, there are such, ask at the pharmacy. You will lay the diaper on the couch, and then wipe off the remaining gel with it after the examination; a condom must be put on the sensor when examining “from the inside”.
3. Before going for screening, it is advisable to perform hygiene procedures - take a shower and change your underwear, however, if you go for the procedure directly from work, then, naturally, you will not have the opportunity to prepare.

How is the first ultrasound procedure performed?

1. Usually, an appointment for the first screening is made in advance. You can come a little earlier, calm down, prepare yourself mentally and drink some water before the doctor’s office so that your bladder is sufficiently full before the procedure begins.
2. On the couch, you will be asked to lie on your back with your knees slightly bent. Do not hesitate to ask the doctor questions; as a rule, very kind and patient people work with pregnant women.
3. First, the examination is carried out externally, with a transabdominal sensor placed in the area of ​​the pubic bone, then they move on to internal diagnostics using vaginal sensors, which makes it possible to give a more accurate and adequate assessment of the functioning and activity of the embryo.
4. When the study is completed, the doctor will give you a documented conclusion about the results of the procedure.

Why the first ultrasound must be done no later than 12 weeks of pregnancy

It is during this period, no earlier and no later, that it is possible to carry out timely diagnosis of chromosomal pathologies and abnormalities in fetal development.

If genetic pathologies are suspected, doctors will conduct an additional examination and, if the result is not encouraging, terminate the pregnancy.

It is at this time that obstetricians determine the exact gestational age of the fetus.

What can you see at screening at 12 weeks of pregnancy?

• The doctor sees the formed fetus and compares its size with the norm. This way the doctor can immediately see abnormalities.
• During this period, the size of the embryo is 6-7 cm in length and weighs about 10 grams. The heart rate of a tiny person is from 100 to 160 beats per minute.
• The timeliness of the baby’s development is assessed and the development of anomalies and genetic diseases is excluded based on medical signs.
• The risk of premature birth is also assessed by examining the placenta insertion site and its position relative to the os of the uterus.
• The amount and structure of amniotic fluid is assessed.
• The date of the upcoming birth can be predicted with an accuracy of 1-2 days.

When will you still need to undergo an ultrasound?

1 pregnancy screening is the most exciting event of the first trimester. The expectant mother waits with bated breath for news about her child - the woman still knows nothing about him! How does the baby develop? Is everything okay with him? The survey will not leave any of these questions unanswered.

The concept of “screening” literally translated from a foreign language means “sifting” and accurately reflects the specifics of the procedure. It is as if expectant mothers are being “sifted” when the indicators of the intrauterine state of their children are determined. Screening is carried out at 11 - 13 weeks of pregnancy. This is a mandatory procedure for all expectant mothers. Such an early date will not prevent precise equipment and experienced specialists from detecting abnormalities in fetal development caused by genetics or chromosomal damage.

Features of the first screening examination

Of primary importance is a comprehensive examination for pregnant women in the following high-risk groups:

• the expectant mother celebrated her 35th birthday;
• in the patient’s family there were cases of the birth of children with Down syndrome and other anomalies due to genetics;
• women who had a spontaneous abortion or gave birth to sick (genetic abnormalities) children;
• victims of infectious diseases that overtook women some time after conception.

The examination includes two procedures: ultrasound and biochemical screening, during which markers specific to the “interesting” position are detected in the blood. These research methods can tell the doctor a lot: whether the baby’s growth rate corresponds to the gestational age and whether there are any pathologies in its development. The test results are interpreted taking into account the age and body weight of the expectant mother, as well as the presence of chronic diseases and bad habits.

When deciphering the data obtained as a result of the examination, the specialist pays attention not only to absolute indicators, but also to deviations corresponding to the timing of screening during pregnancy. All doctors agree that the results of a clinical blood test cannot be taken as the ultimate truth and a final diagnosis cannot be made on this basis. Whatever the results of the study, there is always the opportunity to undergo additional examination.

How is screening done during pregnancy?

Preparation for the procedure begins within the walls of the antenatal clinic, where the expectant mother can ask the gynecologist any questions that interest her. The specialist will tell the woman about the importance of the first screening and explain how to prepare for it.
The laboratory usually performs ultrasound and biochemical blood tests on the same day. The examination is completely painless; the most unpleasant moment can only be considered the blood sampling procedure.

Screening is carried out early in the morning, before breakfast. 1 - 2 days before the procedure, the expectant mother should pull herself together and give up her favorite foods, including chocolate, seafood, meat and all fatty foods. A forced diet is considered the key to accurate screening results.

The doctor will most likely advise the woman to abstain from sexual intercourse, otherwise the overall picture of the tests may be distorted.

Before going to the laboratory, a pregnant woman should weigh herself. The laboratory technician will enter data on the patient’s body weight into a special form immediately before the ultrasound procedure and blood sampling for analysis.

Before screening, it is better not to drink water, but if the desire is irresistible, then no more than 100 ml.

Pregnancy Screening: Purposes of Ultrasound

At the initial stage of gestation, an ultrasound machine is used to determine the main parameters of the growing baby. The laboratory assistant examines the child’s internal organs, paying attention to the location of his arms and legs. In addition, the procedure makes it possible to see the position of the placenta and evaluate its structure. By the characteristics of the baby’s physique during this period of pregnancy, they can judge whether the fetus is forming correctly. If a deviation in the child’s development from generally accepted norms is detected in time, the doctor will have time to conduct an additional examination, think about and develop tactics for further management of the pregnancy.

During the procedure, the specialist examines the following specific features of the developing child:

Coccygeal-parietal distance (CPD)

• 11 weeks - from 34 to 50 mm;
• 12 weeks - from 42 to 59 mm;
• 13 weeks - from 51 to 75 mm.

Condition of the nasal bone

At 11 weeks of pregnancy it should be clearly visible, but its size is still difficult to determine. Screening at 12 weeks of pregnancy shows that the nasal bone has grown - its size now ranges from 2 to 2.5 mm or more. At 10-12 weeks of gestation, the bone is clearly visible in 98% of healthy babies.

Neck thickness (TCT)

In other words, these are folds in the neck area.

• 11 weeks – from 0.8 to 2.2 mm;
• 12 - 13 weeks - from 0.8-2.7 mm.

Heart rate (HR)

• 11 weeks – from 155 to 178 beats per minute;
• 12 weeks – from 150 to 174 beats per minute;
• 13 weeks – from 147 to 171 beats per minute.

Biparietal size

This is the distance between the outer and inner edges of both parietal bones.

• 11 weeks – from 13 to 21 mm;
• 12 weeks – from 18 to 24 mm;
• 13 weeks – from 20 to 28 mm.

Appearance of the maxillary bone

A poorly defined maxillary bone between 11 and 13 weeks may indicate a high risk of developing Down syndrome in the baby.

Based on these indicators, the doctor can draw a conclusion about the child’s developmental characteristics. Thus, the presence of a number of specific signs on the monitor of an ultrasound machine can inform a specialist about possible pathologies in the baby’s development. Let's note what people pay attention to first:

• if, at the established time of screening during pregnancy, the nasal bone of the fetus is still not determined or its size is significantly behind the norm, and the facial contours are inexpressive and smoothed, the specialist will suspect Down syndrome;
• a completely invisible or very small nasal bone, the presence of an umbilical hernia, one umbilical artery instead of the required two and a low heart rate indicate Edwards syndrome;
• a visualized umbilical hernia, impaired development of many body systems and a high heart rate most likely indicate the development of Patau syndrome.

Screening during pregnancy: blood test norms

As a result of a biochemical blood test, the values ​​of free beta-hCG and protein-A (PAPP-A) are of greatest value to the doctor.

In a pregnant woman, the amount of human chorionic gonadotropin in the blood is increased. The concentration of a specific substance increases rapidly in the first weeks after fertilization of the egg. It is by this sign that one can judge whether pregnancy has taken place or not within 6 to 7 days after intercourse.

Starting from the 12th week of gestation, hCG levels in the body begin to gradually decrease, and throughout the second trimester its level remains practically unchanged.

The norms of free hCG during pregnancy are:

• from 17.4 to 130.4 ng/ml at 11 weeks of gestation;
• from 13.4 to 128.5 ng/ml at 12 weeks of gestation;
• from 14.2 to 114.7 ng/ml at 13 weeks of gestation.

A free hCG level that is higher than normal may indicate the following conditions:

• multiple pregnancy;
• Down syndrome;
• severe toxicosis.

Significantly underestimated indicators of this substance indicate the following probable pathologies:

• non-developing pregnancy;
• delayed fetal development;
• the likelihood of spontaneous miscarriage;
• Edwards syndrome.

The standards for the substance PAPP-A are:

• from 0.46 to 3.73 mU/ml at 11 weeks;
• from 0.79 to 4.76 mU/ml at 12 weeks;
• from 1.03 to 6.01 mU/ml at 13 weeks.

• pathology of the development of the fetal neural tube;
• frozen pregnancy;
• the likelihood of spontaneous abortion;
• risk of premature birth;
• Rh conflict between mother and child;
• Edwards syndrome;
• Down syndrome;
• Smith-Opitz syndrome;
• Cornelia de Lange syndrome.

Biochemical analysis of the first screening during pregnancy makes it possible to detect fetal pathologies in the form of Down, Patau and Edwards syndromes in 68% of cases. Taking into account ultrasound data, the reliability of blood test results is confirmed in 90% of cases. However, experts always remember that for some reasons the data obtained may be distorted.

For example, the results of a biochemical blood test depend on many factors, among which the greatest influence on the composition of the blood is:

• multiple pregnancy;
• pregnancy obtained through the IVF procedure;
• the patient’s large body weight (the larger it is, the higher the levels of specific substances in the blood);
• a course of treatment with drugs whose active substance is progesterone;
• diabetes mellitus in a pregnant woman;
• high risk of spontaneous abortion;
• incorrectly determined gestational age;
• depressed state of the expectant mother due to psychological trauma.

If the data obtained as a result of the first screening during pregnancy does not differ too much from the norm, doctors will try to allay their concerns at the second screening. This is a mandatory procedure for the second trimester of pregnancy.

Medical practice knows cases where, despite unfavorable results of biochemical blood tests of the first and second screenings, women gave birth to absolutely healthy children. Let us note that this “miracle” relates only to a blood test, since doctors almost never doubt the reliability of the results obtained from an ultrasound procedure.

Remember that unfavorable results from the first screening are not a reason to panic, as test results may vary depending on your health condition. You have the right to additional examination at your own request. You need to start by consulting a geneticist, who will discuss with you the possibility of additional research methods. This is amniocentnesis, cordocentnesis or chorionic villus biopsy. These procedures will answer your deepest question with amazing accuracy. A kind of bonus that these events will bring you will be absolutely truthful news about who you carry under your heart - a future protector or a princess. This will be revealed by counting chromosomes. In any case, you need to not give up and hope for the best!

Hopes and fears of first pregnancy screening. Video

Prenatal screening examination of the first trimester consists of two procedures: ultrasound diagnostics and blood testing for the possibility of genetic pathologies of the fetus. There is nothing wrong with these events. The data obtained through an ultrasound procedure and a blood test are compared with the norm for this period, which makes it possible to confirm the good or identify the poor condition of the fetus and determine the quality of the gestation process.

For the expectant mother, the main task is to maintain good psycho-emotional and physical condition. It is also important to follow the instructions of the obstetrician-gynecologist leading the pregnancy.

Standards for ultrasound diagnostics I screening

During the first prenatal screening in the first trimester, the ultrasound diagnostic doctor pays special attention to the anatomical structures of the fetus, clarifies the gestational age (gestation) based on fetometric indicators, comparing with the norm. The most carefully assessed criterion is the thickness of the collar space (TVP), because This is one of the main diagnostically significant parameters, which makes it possible to identify genetic diseases of the fetus during the first ultrasound procedure. With chromosomal abnormalities, the nuchal space is usually expanded. Weekly TVP norms are given in the table:

When performing ultrasound screening in the first trimester, the doctor pays special attention to the structure of the facial structures of the fetal skull, the presence and parameters of the nasal bone. At 10 weeks it is already quite clearly defined. At 12 weeks, its size in 98% of healthy fetuses ranges from 2 to 3 mm. The size of the baby’s maxillary bone is assessed and compared with the norm, because a noticeable decrease in jaw parameters in relation to the norm indicates trisomy.

During the 1st screening ultrasound, the fetal heart rate (heart rate) is recorded and also compared with the norm. The indicator depends on the stage of pregnancy. Weekly heart rate norms are shown in the table:

The main fetometric indicators at this stage during the ultrasound procedure are the coccygeal-parietal (CP) and biparietal (BPR) dimensions. Their norms are given in the table:

The first screening involves an ultrasound assessment of blood flow in the ductus venosus (Arantius), since in 80% of cases of its violation the child is diagnosed with Down syndrome. And only in 5% of genetically normal fetuses such changes are detected.

Starting from the 11th week, it becomes possible to visually recognize the bladder during ultrasound. At the 12th week, during the first ultrasound screening, its volume is assessed, since an increase in the size of the bladder is another evidence of the threat of developing trisomy (Down) syndrome.

It is best to donate blood for biochemistry on the same day as the ultrasound screening. Although this is not a mandatory requirement. Blood is drawn on an empty stomach. Analysis of biochemical parameters, which is carried out in the first trimester, is aimed at identifying the degree of threat of genetic diseases in the fetus. For this purpose, the following hormones and proteins are determined:

• pregnancy-associated plasma protein-A (PAPP-A);
• free hCG (beta component).

These indicators depend on the week of pregnancy. The range of possible values ​​is quite wide and correlates with the ethnic content of the region. In relation to the average normal value for a given region, the level of indicators fluctuates within the following limits: 0.5-2.2 MoM. When calculating the threat and deciphering the data for analysis, not just the average value is taken, all possible corrections for the anamnestic data of the expectant mother are taken into account. Such an adjusted MoM makes it possible to more fully determine the threat of developing genetic pathology in the fetus.

HCG: risk assessment

In terms of information content, free hCG (beta component) is superior to total hCG as a marker of the risk of fetal genetic abnormalities. The beta-hCG norms for a favorable course of gestation are shown in the table:

This biochemical indicator is one of the most informative. This applies to both identifying genetic pathology and marking the course of the gestation process and changes occurring in the body of a pregnant woman.

Standards for pregnancy-associated plasma protein-A

This is a specific protein that the placenta produces throughout the gestational period. Its growth corresponds to the period of pregnancy development and has its own standards for each period. If there is a decrease in the level of PAPP-A in relation to the norm, this is reason to suspect the threat of developing a chromosomal abnormality in the fetus (Down and Edwards disease). The norms for PAPP-A indicators during normal gestation are shown in the table:

However, the level of protein associated with pregnancy loses its informative value after the 14th week (as a marker of the development of Down's disease), since after this period its level in the blood of a pregnant woman carrying a fetus with a chromosomal abnormality corresponds to the normal level - as in the blood of a woman with healthy pregnancy.

Description of the first trimester screening results

To evaluate the results of screening I, each laboratory uses a specialized computer product - certified programs that are configured for each laboratory separately. They make a basic and individual calculation of the threat indicators for the birth of a baby with a chromosomal abnormality. Based on this information, it becomes clear that it is better to carry out all tests in one laboratory.

The most reliable prognostic data are obtained by undergoing the first prenatal screening in the first trimester in full (biochemistry and ultrasound). When deciphering data, both indicators of biochemical analysis are considered in combination:

low values ​​of protein-A (PAPP-A) and elevated beta-hCG – a risk of developing Down syndrome in a child;
low levels of protein-A and low beta-hCG are a threat to Edwards disease in the baby.
There is a fairly accurate procedure to confirm a genetic abnormality. However, this is an invasive test that can be dangerous for both mother and baby. To clarify the need to use this technique, ultrasound diagnostic data are analyzed. If there are echo signs of a genetic abnormality on an ultrasound scan, the woman is recommended to undergo invasive diagnostics. In the absence of ultrasound data indicating the presence of a chromosomal pathology, the expectant mother is recommended to repeat the biochemistry (if the period has not reached 14 weeks), or wait for the indications of the 2nd screening study in the next trimester.

Risk assessment

The information obtained is processed by a program specially created to solve this problem, which calculates the risks and gives a fairly accurate forecast regarding the threat of developing chromosomal abnormalities of the fetus (low, threshold, high). It is important to remember that the resulting transcript of the results is only a forecast, not a final verdict.

Quantitative expressions of levels vary in each country. For us, a value of less than 1:100 is considered a high level. This ratio means that for every 100 births (with similar test results), 1 child is born with a genetic pathology. This degree of threat is considered an absolute indication for invasive diagnostics. In our country, the threshold level is considered to be the risk of having a baby with developmental defects in the range from 1:350 to 1:100.

The threshold level of threat means that the child may be born sick with a risk of 1:350 to 1:100. At a threshold level of threat, the woman is sent to see a geneticist, who gives a comprehensive assessment of the data obtained. The doctor, having studied the parameters and medical history of the pregnant woman, identifies her in the risk group (with a high or low degree). Most often, the doctor recommends waiting until the second trimester screening test is performed, and then, having received a new threat calculation, come back for an appointment to clarify the need for invasive procedures.

The information described above should not frighten expectant mothers, and there is also no need to refuse to undergo first trimester screening. Since most pregnant women have a low risk of carrying a sick baby, they do not require additional invasive diagnostics. Even if the examination showed poor condition of the fetus, it is better to find out about it in a timely manner and take appropriate measures.

If unfavorable results are obtained, what to do?

If it so happens that the analysis of the screening examination indicators of the first trimester revealed a high degree of threat of having a child with a genetic anomaly, first of all, you need to pull yourself together, since emotions negatively affect the gestation of the fetus. Then start planning your next steps.

First of all, it is unlikely to be worth the time and money to undergo re-screening at another laboratory. If the risk analysis shows a ratio of 1:100, you cannot hesitate. You should immediately contact a geneticist for advice. The less time is lost, the better. With such indicators, a traumatic method of confirming the data will most likely be prescribed. At 13 weeks, this will be an analysis of chorionic villus biopsy. After 13 weeks, it may be recommended to perform a cordo- or amniocentesis. Analysis of chorionic villus biopsy provides the most accurate results. The waiting period for results is about 3 weeks.

If the development of chromosomal abnormalities of the fetus is confirmed, the woman will be recommended to have an artificial termination of pregnancy. The decision is, of course, up to her. But if the decision is made to terminate the pregnancy, then the procedure is best performed at 14-16 weeks.