Encyclopedia 

How to prepare for the surrender. What is pregnancy screening and why is it done? With elevated levels of hCG can be diagnosed

The first perinatal screening is a comprehensive diagnosis of the future 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, the obtained data will be monitored, based on a comparison of the result with the indications of the screening norm for ultrasound of the 1st trimester. The main task of an individual examination is the early detection of genetic pathologies in the fetus.

Indications for carrying out

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

  • have previously given birth to children with any developmental disabilities;
  • already have a child with fixed genetic pathologies;
  • crossed the threshold of 35–40 years;
  • were exposed to infectious diseases during the period of gestation;
  • have ever suffered from excessive use of alcohol or drugs;
  • have a history on hand with notes about the threat of spontaneous miscarriage;
  • are with the potential father of the baby in a closely related union;
  • for any reason, they took medications that are prohibited for use during the gestation period;
  • know about the presence of hereditary anomalies in the pedigree of the family;
  • have experienced a stillbirth in the past;
  • received a diagnosis indicating the cessation of the development of the child;
  • show an independent desire to analyze the risk of having an infant with special 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 deciphered?

Ultrasound diagnostics are prescribed, as a rule, from 10–11 weeks to 13–14 weeks, since this period of the obstetric period provides the first real opportunity to study the basic structures of the emerging baby. 11-12 weeks 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 decoding the conclusion of the ultrasound. These include: KTP, PAPP-A, heart rate, BDP, TVP, hCG, NK, etc. In order to establish an accurate prediction of 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 respective tables.

Coccyx-parietal size

KTP is one of the most important indicators of 1 screening 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. In the case of deviations of the CTE from its normal range, it can be assumed that the intrauterine development of the unborn child is endangered.

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


KTP is one of the main indicators of the condition of the fetus

Heart rate

Regular medical monitoring is necessary for the state of heart rate, 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 SS rhythm matches the mother's heart rate. The average value is in the range from 76 to 84 beats per minute during the normal functioning of the woman's body.

Further, when the heart structure of the fetus 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 the 83–85th day of gestation, using ultrasound diagnostics, such dangerous phenomena as fetal deformity or the complete absence of a heartbeat were not recorded, then a missed pregnancy can be excluded from the list of possible pathologies. The subsequent phases of body formation are less difficult than a 12-week "Spartan marathon".

Provided that improved and high-quality models of medical devices are used for screening, potential parents will be able to get a more informative characterization of the child's current condition. It is not worth resorting to 3D / 4D ultrasound without special need. Such modern devices, although they can register the intrauterine activity and appearance of the baby, but their radiation dose during the abuse of ultrasound can adversely affect the health of the child.

nasal bone length

Changes in the structure of the oblong nasal bone also indicate the presence of abnormalities. Examining the state of fetuses 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 (NC) is performed no earlier than 12-13 weeks. If the doctor scheduled 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 norm of ultrasound, which in fact turned out to be a manifestation of the individuality of the unborn child. In this case, the performance of other tests will comply with the standard.

Collar space thickness

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

If the indicator at the first screening exceeded a thickness of 3 millimeters, then it is possible to suspect damage to chromosome segments 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 than the size of the future baby.

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

The 1st screening should not be neglected, since with its help the sonologist will be able to examine the unique structure more closely, making appropriate conclusions about its condition. If the yolk sac is at risk of destruction, immediate medical attention is needed. 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 notable features include:

  • isolation of extremely important protein structures involved in the construction of protective membranes for embryonic cells;
  • the formation of a capillary network and erythrocytes, which will become the "foundation for laying" the circulatory system of the fetus;
  • temporary replacement of the liver;
  • determination of the sex of the child by delivering to him the gametes developed in the cavity of the yolk sac.

Also, this organ is responsible for protecting the small organism from the mother's antibodies. No matter how ambiguous it may sound, but the cells of the woman's immune system, like soldiers on guard of human health, attack the fetus, seeing it as a potential threat - a foreign element. In order to provide the embryo with a safe 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 affects the course of the upcoming pregnancy, therefore, with a comprehensive examination, it is given a lot of time. According to the medical standard, this organ should not be located in the lower region of the uterus, since its abnormal structure provokes the overlap of the birth canal. Such a frequent gynecological deviation is called presentation.

The detection of an ailment at the first screening during early pregnancy is far from always a cause for concern. At an early stage, there is still a chance to change the extremely precarious position - in the subsequent time of gestation, the uterus may rise, while 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, also registered in the results of the first screening. Without going into the details of medical terminology, we can say that this indicator involves measuring the head along the minor axis - the distance from one temporal bone to another. The biparental size of the fetus is of particular value, primarily because of the 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 an ultrasound specialist.

If there are no suspicious signs in the final screening data, then the brain develops in the normal mode. A lower index indicates a lack of any parts of the brain or a delay in its development.

Blood chemistry

After the results of ultrasound diagnostics are obtained, on the basis of which the actual gestational age is determined, the pregnant woman will have to go through 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 of its content are found out only from 12–13 weeks, however, as an exception, the blood sampling procedure is carried out a little earlier.

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 content gradually drops, fixing at a stable rate.

As soon as the patient passes perinatal screening in full, doctors will begin to compare the identified indices with the norm, making a full-fledged final conclusion.

What pathologies can be detected at the 1st screening?

With the help of a comprehensive study in the first trimester, you can find a fairly impressive list of pathologies that cause complications of various severity, starting with the deformation of an organ and ending with the death of a baby. The most commonly diagnosed 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.

The above congenital diseases have the right to diagnose only a doctor, since the decoding of ultrasound performed by the patient on his own may be done incorrectly. The formation of a diagnosis based on the indicators of the first screening implies a comprehensive qualitative analysis of all the data obtained, taking into account each aspect and the "pitfall". That is why expectant mothers are advised to trust their health and the life of the baby only to a professional in their field. The constructive unity of the patient with the attending physician increases the likelihood of having a healthy child.

Screening of the 1st trimester, what is it and when should it be carried out? Is it mandatory and how accurately are the results interpreted? This examination is a combination of two - ultrasound and blood tests, which must take place on the same day.

Prenatal screening in the 1st trimester is considered reliable if 2 conditions are met.
1. It was performed by an experienced specialist in terms of 11 to 13.6 weeks. In this case, the CTE of the fetus should not be less than 45 mm, otherwise the measurement of TVP (collar space) cannot be considered reliable for calculating the risk of having a child with chromosomal pathologies.

2. Risks should be considered, not relying only on ultrasound data, and not looking only at biochemical screening of the 1st trimester. This work must be performed by a special program. And it will give a result on the risks for various genetic and chromosomal diseases. The risks will be registered as average (where only age is taken into account) and individual. So the screening of the 1st trimester is bad if the individual risks are higher than the base (age). In this case, the doctor may refer you for a consultation with a geneticist. And already he, perhaps, will prescribe as soon as possible to repeat ultrasound, only an expert class and (or) invasive diagnostics (cordocentesis, chorionic villus biopsy or amniocentesis). Recommendations will largely be based on ultrasound data. Sometimes at this time, the doctor of ultrasound diagnostics sees very severe malformations in the fetus that are incompatible with life. In this case, a second ultrasound is prescribed and interruption is recommended. Invasive diagnosis is usually not necessary.

If the ultrasound screening of the 1st trimester is generally normal, but the individual risk of having a sick child is high, then the doctor may recommend waiting for the second screening or conducting an invasive diagnosis, the result of which will tell you exactly whether the child is genetically healthy.

In the early stages, a chorionic villus biopsy is performed - this is a rather risky procedure, in terms of a high risk of miscarriage after it. For genetic analysis, the doctor takes cells from the placenta, this procedure is also called a placental biopsy.

After 16 weeks, amniocentesis is done. Amniotic fluid is taken for analysis. This analysis is considered very informative and safer than chorionic villus biopsy and cordocentesis. Women usually agree to the first one in order to avoid prolonged bearing of a non-viable fetus. After all, after 12-13 weeks, you need to wait for the period when doctors can induce artificial labor. And that's about 18 weeks.

But if you didn’t fall into the norms of screening for the 1st trimester by ultrasound, and you don’t want to wait for the second screening, and even more so for invasive diagnostics, there is an opportunity to do a non-invasive test. While in Russia it is not common. And very expensive. An analysis costs about 30,000 rubles. But its reliability is about the same as amniocentesis. There is no risk of spontaneous abortion.

1st trimester screening involves looking at the levels of two hormones in the blood of the expectant mother - hCG and PAPP-A. High hCG may indicate a high risk of Down syndrome in a child, and low hCG may indicate Edwards syndrome. At the same time, PAPP-A is also low. But the final interpretation of the results of screening of the 1st trimester is performed only together with ultrasound.

The result of blood tests can be affected by a situation where a woman has a clear threat of miscarriage if she takes progesterone preparations. But with the threat flow very many pregnancies. In addition, a woman carries one or several fetuses, whether she has excess or underweight, whether the conception was natural or in vitro fertilization. Therefore, it is completely wrong to try to interpret and worry about separate blood tests.

When it is better to do screening of the first trimester - the gynecologist can and should calculate directly. That is why it is important to register for pregnancy before 12 weeks. It is advisable to come to the doctor for the first time no later than 8-9 weeks, since there is a shortage of coupons for free screening in many Russian regions. You may need to wait a bit to get a ticket. You just have to wait for this extra time.

But the timing of the screening of the 1st trimester has been determined. It remains only to donate blood and do an ultrasound on the specified day. Many women believe that for greater reliability of the result, some measures need to be taken. Should there be preparation for the first screening during pregnancy and what kind? As such, no preparation is needed. Some experts recommend following a diet a few days before the examination, but this is not very necessary. There is no need for a future mother to limit herself in nutrition. And one more important question - how is the first trimester screening done on an empty stomach or not, what is the best way? In general, it is advisable to take all blood tests on an empty stomach. Including this one. But sometimes it happens that the analysis is scheduled for the second half of the day. Then, of course, you should not starve from the evening of the previous day.

An ultrasound is performed. And sometimes the doctor needs not only abdominal access, but also vaginal. Indicators that are of particular interest to the doctor are the thickness of the collar space, the visualization and size of the nasal bone, and the speed of venous blood flow. In addition, the doctor looks at all the organs and systems of the fetus, the size of the limbs, the head. Measures the cervix of a woman in order to diagnose isthmic-cervical insufficiency at an early stage, if any.

The results of the 1st trimester biochemical screening are usually ready within a few days. And all this time, the expectant mother is in suspense. Especially if you read or personally know the bad stories associated with this survey. Usually a woman visits a doctor once every 2-3 weeks, and if a high-risk screening result arrives before she is due to attend an antenatal clinic, the doctor or midwife calls her and invites her to come. If there is a good screening of the first trimester, you don’t have to worry and don’t take anything extra and don’t visit genetics. It should be noted that young women have a much lower risk of chromosomal abnormalities.

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

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

Ultrasound is only one examination of the screening complex. To get complete information about the health of the baby, the doctor must check the blood of the future woman in labor for hormones, evaluate the result of a general urine and blood test

Standards for ultrasound diagnostics I screening

In the process of conducting the first prenatal screening in the 1st trimester, the ultrasound diagnostician pays special attention to the anatomical structures of the fetus, specifies the gestation (gestation) period based on fetometric indicators, comparing with the norm. The most carefully evaluated criterion is the thickness of the collar space (TVP), since. 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 collar space is usually expanded. Weekly TVP norms are shown in the table:

When conducting ultrasound screening of 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 is from 2 to 3 mm. The baby's maxillary bone size is evaluated and compared with the norm, because a noticeable decrease in jaw parameters in relation to the norm indicates trisomy.

On ultrasound 1 screening, the fetal heart rate (heart rate) is recorded and also compared with the norm. The indicator depends on the gestational age. Weekly heart rate rates are shown in the table:

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


Fetal age (week)Average CTE (mm)Average BPR (mm)
10 31-41 14
11 42-49 13-21
12 51-62 18-24
13 63-74 20-28
14 63-89 23-31

The first screening involves an ultrasound assessment of blood flow in the venous (Arancius) duct, since in 80% of cases of its violation, a child is diagnosed with Down syndrome. And only 5% of genetically normal fetuses show such changes.

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 that ultrasound screening is performed. Although this is not a requirement. Blood sampling is carried out on an empty stomach. The 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, the following hormones and proteins are determined:

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

These figures 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 this region, the level of indicators fluctuates within the following limits: 0.5-2.2 MoM. When calculating the threat and deciphering the data, not just the average value is taken for analysis, all possible amendments to the anamnestic data of the expectant mother are taken into account. Such an adjusted MoM allows you to more fully determine the threat of developing a genetic pathology of the fetus.


 A blood test for hormones is necessarily performed on an empty stomach and is often scheduled on the same day as the ultrasound. Due to the presence of standards for the hormonal characteristics of the blood, the doctor can compare the results of the tests of a pregnant woman with the norms, identify a deficiency or excess of certain hormones

HCG: assessment of risk values

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

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

Pregnancy-Associated Plasma Protein-A Guidelines

This is a specific protein that the placenta produces throughout the entire gestational period. Its growth corresponds to the period of development of pregnancy, 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 a reason to suspect the threat of developing a chromosomal abnormality in the fetus (Down and Edwards disease). The norms of PAPP-A indicators for normal gestation are indicated in the table:

However, the level of pregnancy-associated protein loses its information content after the 14th week (as a marker for 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 a normal indicator - as in the blood of a woman who has healthy pregnancy.

Description of 1st trimester screening results

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

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

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



 Chromosomal disorders of fetal development are most easily detected using a biochemical blood test. However, if the ultrasound did not confirm the fears, it is better for the woman to repeat the study after a while, or wait for the results of the second screening.

Risk assessment

The information received 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 fetal chromosomal abnormalities (low, threshold, high). It is important to remember that the resulting transcript of the results is only a forecast, and not the final verdict.

In each country, the quantitative expressions of the levels vary. We consider a high level to be less than 1:100. 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 the threat of the birth of a baby with malformations in the range from 1:350 to 1:100.

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

The information described above should not scare expectant mothers, nor should you refuse to undergo first trimester screening. Since most pregnant women have a low risk of carrying a sick baby, they do not need additional invasive diagnostics. Even if the examination showed a poor condition of the fetus, it is better to find out about it in a timely manner and take appropriate measures.



 If studies have revealed a high risk of having a sick child, the doctor must honestly convey this information to parents. In some cases, an invasive study helps to clarify the situation with the health of the fetus. With unfavorable results, it is better for a woman to terminate the pregnancy at an early stage in order to be able to bear a healthy child.

If adverse results are obtained, what should be done?

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

First of all, it is hardly worth spending the time and money to get re-screened in another lab. If the risk analysis shows a ratio of 1:100, you can not hesitate. You should immediately contact a geneticist for advice. The less time wasted, the better. With such indicators, most likely, a traumatic method of confirming the data will be prescribed. At 13 weeks, this will be an analysis of the chorionic villus biopsy. After 13 weeks, it may be recommended to perform cordo- or amniocentesis. Analysis of the chorionic villus biopsy yields the most accurate results. The waiting time for results is about 3 weeks.

If the development of fetal chromosomal abnormalities is confirmed, the woman will be recommended artificial termination of pregnancy. The decision is definitely up to her. But if a decision is made to terminate the pregnancy, then the procedure is best done at 14-16 weeks.

Screening helps to identify pathology in the early stages of fetal development. This set of diagnostic measures is aimed at assessing the rate of intrauterine development of the baby by comparing the indicators with the gestational age. The procedure is mandatory and is carried out for all expectant mothers.

Why is screening necessary during pregnancy?

Screening during pregnancy is a mandatory procedure, during which the risk of developing abnormalities in the fetus is established. Diagnostic procedures help to identify a predisposition to the development of genetic abnormalities of the fetus, to establish a discrepancy between the development of the internal organs of the baby and the gestational age.

The procedure is advisory in nature, but women never refuse to conduct it, knowing the significance of such studies. There are also indications, the presence of which determines the mandatory conduct of the study:

  • the age of the woman is more than 35 years;
  • Availability ;
  • history of spontaneous abortion;
  • the presence of fetal chromosomal abnormalities in past pregnancies;
  • transferred infections in the short term;
  • forced intake of drugs that are contraindicated for short periods;
  • the presence of bad habits (alcoholism, drug addiction);
  • close relationship between the father and mother of the child.

1st trimester screening - what is it?

The first screening during pregnancy is a comprehensive examination of the maternal body. In its implementation, doctors pursue the goal of early diagnosis and further correction of anomalies in the development of the fetus. In parallel, an assessment of the health status of the expectant mother is also carried out. Screening of the 1st trimester consists of an ultrasound and a biochemical study of the blood of a pregnant woman. The evaluation of blood parameters is carried out at the second stage, in the presence of deviations and suspicions of pathology based on the results of ultrasound. The stages are carried out sequentially, it is allowed to carry out two procedures on the same day.

Ultrasound screening 1st trimester

Ultrasound during pregnancy is important. With the help of ultrasound, doctors manage to look into the mother's womb, assess the state of a small organism, its internal organs. In the course of such a study, as part of the screening of the 1st trimester, doctors pay attention to anthropometric indicators, which are an indicator of the correct development of the fetus, the correspondence of the size of its body to the gestational age. When the screening of the 1st trimester is carried out, the doctor pays attention to the following parameters:

  • KTP (coccyx-parietal size);
  • the size of the fetal head;
  • symmetry of the cerebral hemispheres;
  • the size of long tubular bones;
  • the size of the heart and the diameter of the vessels departing from it;
  • localization of the stomach and other internal organs.

Biochemical screening of the 1st trimester

Doctors prescribe such tests during pregnancy after receiving a bad ultrasound result. Suspecting a pathology on the monitor screen, doctors want to make sure the objectivity of the assumptions put forward. It is worth noting that this study should be carried out exclusively at a certain gestational age, since the norms of indicators directly depend on the stage of gestation. In a biochemical blood test, attention is paid to the following indicators:

What does the first screening show?

During the first screening, doctors try to exclude possible chromosomal abnormalities. These violations do not manifest themselves outwardly, their presence does not affect the condition of a pregnant woman. However, they can be identified by characteristic changes in the appearance of the fetus and by the presence of certain markers in the blood of the expectant mother. Among the possible pathologies that screening of the 1st trimester helps to identify:

  1. Down syndrome- chromosomes, occurs in 1 out of 700 cases.
  2. Neural tube pathologies(encephalocele).
  3. Omphalocele- with this pathology, part of the internal organs is placed under the skin of the anterior abdominal wall, in the hernial sac.
  4. Patau Syndrome- trisomy on chromosome 13. Rare, 1 in 10,000 pregnancies. Accompanied by severe damage to internal organs. 90% of babies born with this pathology die during the first year of life.
  5. Edwards syndrome Trisomy 18 chromosome. Occurs in 1 out of 7000 cases. It often occurs in old-born mothers (pregnant women after 35 years).
  6. triploidy- the baby is diagnosed with a triple set of chromosomes, which is accompanied by multiple malformations.
  7. Cornelia de Lange syndrome- characterized by the development of numerous defects in the fetus with the onset of mental retardation in the future.

How is first trimester screening done?

Screening during pregnancy in the 1st trimester is carried out in a strict time frame. The woman is informed in advance of the time of its holding. At the appointed time, she comes to the consultation and first undergoes an ultrasound scan. This study can be carried out transvaginally (through the vagina) or transabdominally (through the anterior abdominal wall). In general, the procedure for the patient does not differ from conventional ultrasound. After receiving the results, if a pathology is suspected, a biochemical blood test is prescribed. The material is taken from a vein, on an empty stomach in the morning.


First screening during pregnancy - timing

To set themselves up, to prepare in advance for the study, women often ask doctors when they do screening for the 1st trimester. The timing of this examination is very limited - in order to obtain objective results, it must be carried out strictly at certain times of pregnancy. The optimal period for a screening study is from the first day of the 10th week of pregnancy to the 6th day of the 13th week. In most cases, the first screening during pregnancy, the terms of which are mentioned above, is carried out at 11–12 weeks of gestation. At this time, the error in the calculations is minimal.

Preparing for 1st trimester screening

In order for the screening of the first trimester to be objective, doctors insist on following the rules for preparing for the study. In the case of ultrasound, everything is simple: if it is carried out with a transvaginal sensor, then special preparation is not required; if through the anterior abdominal wall - it is required to fill the bladder before the ultrasound procedure.

Preparation for a biochemical blood test is more complex and includes:

  1. Compliance with the diet: exclusion from the diet of citrus fruits, seafood, chocolate.
  2. Refusal of fried and fatty foods.
  3. Blood is given in the morning, on an empty stomach. The last meal should take place no later than 12 hours before the expected time of analysis.

Screening results of the 1st trimester - transcript, norm

After the screening of the 1st trimester is carried out, the interpretation of the results is carried out exclusively by the doctor. The pregnant woman is unable to objectively evaluate the obtained values, even when comparing them with the normal values. Each pregnancy has its own characteristics, so the result should be evaluated taking into account the course of gestation, its duration, the state of the female body, and the number of fetuses.

When evaluating the indicators of the individual development of the baby, obtained using ultrasound, doctors pay attention to the following parameters:

  • KTP - the size of the fetus from the crown to the coccyx;
  • body length - the size of the baby's body from the crown to the heels;
  • Head circumference;
  • BDP (biparietal size) - the distance between the dark tubercles;
  • TVP - collar space thickness;
  • HR is the baby's heart rate.

When conducting biochemical screening during pregnancy, two main indicators are paid attention to:

  • β-hCG - chorionic gonadotropin;
  • PAPP-A is pregnancy-associated protein-A.

Screening norms of the 1st trimester - ultrasound transcript, table

In each individual case, doctors, when evaluating the results of ultrasound screening of the 1st trimester, make an adjustment for the individual characteristics of the development of the fetus. Given this fact, doctors allow a slight deviation of the indicators from the established norms. In addition, another factor may also affect the results of the studies - the error in calculating the term carried out by the obstetrician. When conducting the first screening during pregnancy, the norms of which are shown in the table below, doctors first determine the exact gestational age.


1st trimester screening - interpretation of blood results

As noted above, a pregnant woman’s blood is used when a pathology is diagnosed or there is a suspicion of it with ultrasound. At the same time, doctors pay attention to the following indicators:

  1. β-hCG- chorionic gonadotropin, a hormonal substance synthesized by the chorion. With the help of it, pregnancy is diagnosed at an early stage. However, an important indicator is it during the entire 1 trimester. Every day, the concentration of hCG increases, reaching a maximum by 11-12 weeks of gestation.
  2. PAPP-A- protein-A associated with pregnancy. This protein compound is produced by the placenta, responsible for its normal development and functioning. After the biochemical screening of the 1st trimester has been carried out, the interpretation of the results is carried out by the doctor observing the pregnant woman. The values ​​of these indicators by gestational age are given in the tables below.

Gender of the baby at the first screening

Prenatal screening of the 1st trimester does not allow you to reliably determine the gender of the unborn baby. Given this fact, doctors do not attach much importance to this indicator. However, at the request of the mother herself, a specialist with a convenient location of the fetus can make his own assumptions about the sex of the fetus. In practice, they do not always coincide with reality and are often erroneous, so when the first screening is done, this parameter is not taken into account.


Pregnancy is always considered the main event in the life of every person. Especially for the female. As soon as the second strip appears on the test, according to the definition of pregnancy, it is already known that life will change and everyone is looking forward to the first ultrasound examination. If, of course, it is interesting to look at the future baby, then you can contact any paid clinic. In addition to the fact that they will give the result of an ultrasound on their hands, they will also give a picture of the baby.

Those who have reached the age of 35 years and above undergo all the necessary examinations in more specialized clinics. For example, if in the city of Nizhny Tagil they are sent for screening in the 1st trimester to the perinatal center of the city of Nizhny Tagil, then women over the age of 35 are sent to the city of Yekaterinburg. And there are more surveys.

The first ultrasound is performed at an early stage of pregnancy, this period reaches 11-13 weeks, that is, this is the third month of pregnancy. In the field of medicine, such an ultrasound is usually called screening.

First ultrasound

Screening in the 1st trimester is not just an ultrasound, as many people think. Screening is an advanced test that will tell you how well your pregnancy is going. Since screening is aimed at recognizing whether the baby has congenital malformations or serious diseases that will later develop into pathologies.

Many people ask why this examination is carried out at such an early stage and why it is carried out in specialized centers.

At this time, if violations are detected in a child, a certain course of treatment can be prescribed in a timely manner, or, in an accident, it can be done. Of course, such cases are rare, but still they have a place to be.

And the examination in the center is carried out due to the fact that the antenatal clinic is not equipped with such equipment, which can detect violations. Perhaps in the future such a survey will be carried out in antenatal clinics, but not now.

The examination consists of a visit to the ultrasound diagnostics room, a treatment room and a final consultation with an obstetrician-gynecologist.

How to prepare for screening

What is required for this screening? The main thing is a positive moral attitude. Since every girl during the examination, of course, is nervous and worried. And this is not surprising, because there are many situations when girls are told far from the most pleasant result of the examination.

In the antenatal clinic, in which the girl is observed, they will issue a referral for an examination. Among which there will be an instruction with instructions on what you need to have with you during the examination, as well as the referral from the antenatal clinic itself. The direction also contains several spectra:

  • is the direction to ;
  • referral for blood donation to determine pathologies through chromosomes;
  • referral required for examination by an obstetrician-gynecologist.

In addition to all of the above areas, you must have with you:

  • exchange notification card of a pregnant woman;
  • 2 copies of the passport;
  • 2 copies of the policy and a diaper.

How the examination is carried out

First, go to the registry office, where you give all the necessary documents. I would like to note right away that if you plan to undergo medical treatment with your soulmate, then this will not work. Since doctors prohibit the presence of another person during the passage of this particular screening. In the future, when screening in the 2nd trimester, you can have an ultrasound with someone.

Also, in specialized centers, the development of any diseases often occurs, which leads to the fact that the center will be closed for quarantine. When closed for quarantine, only pregnant women will be allowed to enter the premises.

After registration, you will be given a list of rooms that must be completed in a certain order. Initially, it will be an ultrasound diagnostic room.

When you visit the ultrasound room, you are initially weighed on the scales, and then go to the couch. According to doctors, they are initially sent for an ultrasound in order to determine whether the size of the baby corresponds to the deadline for undergoing a full examination. Since the obstetrician-gynecologist could incorrectly calculate the term and issue a referral. In this case, the center will re-register for a more suitable time for the examination. But if, nevertheless, the period corresponds to passing the screening, then the doctor will consider the necessary indicators at the ultrasound.

Visit to the ultrasound diagnostic room

To begin with, you will need the exact date of the last one, since doctors enter this data into the protocol of an expert ultrasound examination. At the time of the study, the type of pregnancy is determined, as you know, it can be ectopic and uterine. Next, the cardiac activity of the fetus is considered, that is, whether the baby has a heartbeat and with what frequency.

The coccyx-parietal size (KTR) is an integral part of the ultrasound examination. Because according to the KTR data, they put the estimated date of birth and determine what is the exact date at the time of the examination.

The thickness of the collar space (NTP) at screening in the 1st trimester is a necessary indicator. After all, passing this examination is necessary to confirm the presence and absence of the most terrible disease, such as. It is by the indicator of TVP that one can determine the presence or absence of this syndrome. In the future, we will consider what data on this indicator should not attract special attention.

  • biparietal size (BDP);
  • head circumference (OG);
  • abdominal circumference (OC);
  • thigh length (DLB).

Doctors also attach particular importance to the location of the chorion. Which is also determined by ultrasound. In the following, we will consider why the location of the chorion is important information.

Also, ultrasound determines the length of the cervical canal and the umbilical cord, more precisely, how many vessels there are.

At the end of the protocol, items are observed: markers of fetal chromosomal pathology and an assessment of the fetal anatomy. In the protocol, these items are highlighted in bold, as they require special attention from the doctor.

Most often, the markers of fetal chromosomal pathology indicate the identified abnormalities in the fetus, but almost everyone notes that the nasal bone is determined. There is nothing to worry about, it's just that the doctor during the examination could not consider the size of the nose bone, but the presence of this bone is available. The very meaning of the word “determined” means that which is actively visualized, that is, it is clearly visible. But it is impossible to determine the size of the nose bone.

A fetal anatomy assessment describes what the head (brain), spine, heart, stomach, bladder, kidneys, arms, and legs look like. When considering the arms and legs, the description is made by quantity. That is, in relation to the quantity, the protocol indicates that two arms and two legs.

Deadline for ultrasound

At the end of the protocol, a conclusion is drawn, which describes what the deadline is. Since the term for ultrasound is determined precisely by the size of the baby.

After ultrasound, a picture and protocol of an expert ultrasound examination. If you wish, you can take a picture with your phone, because when you go through the procedure room, the picture will be taken away and sent for blood sampling for biochemical material.

After blood sampling, an examination by an obstetrician-gynecologist follows. The result of the blood sampling will be in the antenatal clinic at the obstetrician-gynecologist. Usually the result is ready in 2 weeks, but this result will not be handed out.

When visiting an obstetrician-gynecologist, blood pressure, weight are measured at screening and they will consider what chronic diseases are present. The result of the consultation is handed over, signed by the doctor. As a result, an examination by a doctor, a diagnosis and recommendations will be described.

In the end, the protocol and the result of the visit to the obstetrician-gynecologist will remain on hand. Be sure to make photocopies of the results and give them to your obstetrician-gynecologist when visiting the antenatal clinic. The originals will remain on the exchange card.

This completes the 1st trimester screening. It remains only to wait for the results of blood sampling. If the ultrasound has already given a positive answer, then as a result of good tests, you can be sure. But if any abnormalities are reported, then the blood result must be awaited to confirm the presence or absence of these abnormalities. I would also like to note that blood is taken on an empty stomach, and the entire examination can take 3-4 hours.

Therefore, be patient and have some chocolate so that you can have a snack after donating blood. Also, the instructions will indicate what should not be eaten the day before the examination. In no case do not eat sweets and citrus fruits. Since blood sampling will also be carried out for the presence of sugar.

During the screening in the 2nd trimester, it will take much less time. Since you just have to go through the ultrasound diagnostic room, they will also issue a protocol, but without a picture. In some centers, you can ask for a picture in your hands, but for a fee.

Interpretation of 1st trimester screening results

All experiences are already left behind, and many girls begin to actively study the data that are described in the ultrasound protocol. Although on the right side it is indicated whether there are deviations from the norm, in the form of a segment on which the norm is indicated by a bar and the measured indicators as a bold dot.

The KTP indicator is correlated with the weight of the fetus, and what is the gestational age by the date of the last menstruation. It was already mentioned earlier that this indicator is important in the survey. This indicator is oriented by measuring the distance from the baby's crown bone to his tailbone. Of course, a longer gestation period corresponds to a larger coccygeal-parietal size.

  • at week 10 - from 33 to 49 mm;
  • at week 11 - from 42 to 58 mm;
  • 12 weeks - from 51 to 83 mm;
  • at 13 weeks of gestation - from 63 to 89 mm.

As you can see, the data on KTR vary among themselves. For example, if the indicator is 71.4 mm, then experts will attribute these data to the thirteenth week of pregnancy.

When this figure is slightly above the norm or, on the contrary, slightly less, then there is no particular reason for panic. It's just the development of the baby.

If the KTR indicator is much higher than the norm, then this indicates that in the future the child will be quite large in size, that is, at birth, the child may exceed the usual body weight. But if the KTR is much lower, then this can indicate a lot of problems. Among which are:

  • abnormal development of pregnancy;
  • insufficient amount of hormones;
  • infectious diseases;
  • genetic abnormalities.

The latter cause will only be confirmed when blood results are received.

Biparietal size

The distance between the walls of the parietal bones of the skull

BDP is determined by the distance between the walls of the parietal bones of the skull, that is, in other words, the size of the head. BDP demonstrates not only how correct the development of the baby is, but also helps medical workers prepare for the next. That is, whether the girl herself will give birth or will

C-section. According to normal indicators, the data varies as follows:

  • 10 weeks - 14 mm;
  • 11 weeks - 17 mm;
  • 12 weeks - at least 20 mm;
  • 13 weeks - 26 mm.

For example, if the indicator is 23.5 mm, then the obstetrician-gynecologist will set a period of 13 weeks. This confirms the data on the KTP indicator.

When BDP data deviate from the established measures, this indicates the presence of a cerebral hernia or tumor, spasmodic development, a large size of the baby, a violation of the development of the brain, which arose in the presence of infectious diseases in the expectant mother. If deviations are observed in a smaller direction, then this indicates that the development of the brain is carried out incorrectly.

Collar space thickness

The collar space in a child or the size of the cervical fold (CNT) is the place located between the neck and the upper skin of the baby's body, in which there is an accumulation of fluid. This indicator is necessary for the early diagnosis of Down syndrome. Normally, this indicator should be:

  • at week 10 - 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 to 2.7 mm.

For example, if the indicator is 1.96 mm, then of course it can be equated to any period. But since the two previous indicators show the gestational age, then we equate our indicator precisely to the 13th week.

Deviations in TVP may indicate the presence of:

  • Patau syndrome;
  • Down syndrome;
  • Shereshevsky-Turner syndrome;
  • Edwards syndrome.

Confirmation of the presence of these syndromes in a child is possible only after receiving blood tests. Since in the treatment room blood is donated for the presence or absence of diseases. If you notice, on one of the directions that they will ask in the treatment room, it says "Screening for Down Syndrome." It is in this direction that blood is taken.

Fetal heart rate

Heart rate is also the main indicator of the proper development of the baby. Therefore, it is important to constantly monitor the baby's heartbeat. If the pregnancy proceeds without consequences, then the results of the study are approximately as follows:

  • 10 weeks - from 161 to 179 beats / min;
  • 11 weeks - from 153 to 177 beats / min;
  • 12 weeks - from 150 to 174 beats / min;
  • 13 weeks - from 147 to 171 beats / min.

The longer the gestation period, the lower the baby's heart rate. Since the heartbeat of a child will tend to the heartbeat of an adult. For example, if the indicator is 158 beats / min, then, like the previous indicator, we equate it to the set deadline and observe whether there are deviations or not. In this case, there are no deviations. Violation of these indicators can show malformations in the development of the heart.

Today, for expectant mothers, many pharmacies and Internet sites offer the purchase of a Doppler. This device helps the expectant mother to independently control the heart rate of the baby at home. Doppler looks like a player for listening to audio recordings. The kit includes an instruction manual, earphones, charger and lubricant gel.

It is not expensive in terms of cost, but if you are really worried about the development of the baby, then do not pay attention to the price. If a deviation from the norm is detected using a Doppler, you can immediately consult a doctor and report a violation of the heartbeat.

Location of the chorion

The last indicator that we will consider in this article is the chorion. Chorion is one of the indicators of a normal pregnancy. Without it, the child will not be able to develop as expected and will simply die. The chorion can be located on the back wall, anterior location and lateral location.

Many have chorion previa. With this detection, it is necessary to observe physical rest, sexual rest (lack of intimate relationships), and taking medications. Compliance with the recommendations of the doctor will help to avoid irreversible consequences, and the birth will be successful.