1st trimester screening when best to do. Deciphering the first ultrasound screening. When and in what cases is screening prescribed during pregnancy

In this article, we will analyze what the concept of "screening" is in general, why and in what terms prenatal screening is carried out, that it allows you to determine whether it is necessary to do this study for all pregnant women, whether it is possible to find out the sex of the child at the first screening and how to properly prepare to research.

The first screening during pregnancy what shows

Screening ("screening") is a mass examination of the population using safe methods to identify a disease or high-risk groups. Prenatal means "before birth".
Prenatal screening is a comprehensive examination of pregnant women, which allows to identify women at risk of fetal malformations before childbirth. Before the advent of this method, the experience of a woman during all 9 months of pregnancy could be defined by the phrase "pig in a poke." Only after the birth of the baby and all the hardships, inconveniences, worries and worries experienced during these 9 months, the mother could find out if her baby was healthy. Or get a terrible verdict "Down's syndrome", etc. And how to live with this?
The advantage of prenatal genetic screening is to detect fetal chromosomal disorders associated with malformations even before delivery and, if the disease is accurately identified, give the pregnant woman a choice whether to continue this pregnancy or terminate it while there is time. And in most cases, this is the most humane solution for both the parents and the child.

During the first screening, the risks of Down syndrome (trisomy 21), Patau syndrome (trisomy 13), Edwards syndrome (trisomy 18) are calculated.
And also this method allows you to suspect a number of other developmental anomalies:

Cornelia de Lange syndrome, manifested by multiple developmental anomalies, from which the child most often dies in the first months. If the child survives, then he has severe mental retardation.
Smith-Lemli-Opitz syndrome - the severity of the disease can vary from minor violations of physical and intellectual development to severe defects and profound mental retardation.
Triploidy (when the genetic set is represented by 69 chromosomes instead of the normal 46), accompanied by multiple defects and mental retardation, the surviving child lives from several months to several years.

For screening of the 1st trimester, the following data are taken into account:

questionnaires, which indicate the parameters of a woman (height, weight), the presence of bad habits (alcoholism, smoking, drug addiction), chronic diseases (that occurred before pregnancy), hormonal disorders detected before pregnancy, method of conception (whether in vitro fertilization methods were used);
a biochemical blood test, including the determination of β-hCG and the PAPP-A protein.

There are no strict recommendations as to whether tests should be taken and ultrasound done on the same day or different ones. Therefore, you can do an ultrasound scan and donate blood for hCG and PAPP-A as you like. The main thing is that each of the studies fit into the recommended time frame.

1st trimester screening when done

In order for the screening results to be reliable, it must be carried out within the strict recommended time frame: this is the beginning of 11 weeks (minimum 10 and 1 day) to 13 weeks and 6 days. Earlier screening is not recommended, because before this time the thickness of the collar space is too small. And from the 14th week, the collar space is filled with liquid and thickens, so the results will no longer be reliable. The most optimal are 11-12 obstetric weeks for this study.

Is screening necessary during pregnancy?

According to the pregnancy management protocol, prenatal genetic screening is recommended for all pregnant women. But this method is not required. Therefore, a woman may refuse to conduct it. Screening is indicated for women at risk. But no one has the right to force a woman to undergo any research. If a woman refuses this study with the available indications for it, then she assumes this responsibility. Prenatal screening is indicated:

if the expectant mother is 36 or more years old;
if one of the parents or their relatives had genetic diseases;
if a pregnant woman in the early stages suffered infectious diseases;
if earlier this woman's pregnancy died or was interrupted, or a dead fetus was born;
if the child's father is closely related to the mother;
if during pregnancy or at the planning stage, alcohol, narcotic substances or drugs were taken that cause a teratogenic effect (leading to malformations) in the fetus;
in the presence of genetic diseases in other children;
in the presence of occupational hazards.

Is it possible to find out the gender at the first screening

Since the first screening is carried out at the 11th - 14th weeks, and the earliest period at which an experienced doctor of functional diagnostics can determine the sex of the fetus (but not yet reliably) is 15 weeks, then at the first screening no doctor will be able to determine the sex of the child. We'll have to live a few more weeks, tormented by this question.

Screening 1 trimester results normal

The correct screening result is represented by an indication of the individual risks of trisomy, which are compared with the baseline. If the conclusion only indicates the levels of hCG, PAPP-A and the conclusion of an ultrasound scan, this is not a screening. These are separately conducted ultrasound and biochemical analyzes. For screening, special calculation programs (PRISCA, ASTRAIA, etc.) are used, which, based on all the data obtained, derive the individual risk of a genetic disease in a particular fetus.
For details on the results of the first screening and how to interpret them, read the article.

Preparation for 1 screening

Some sources give long lists of recommendations and restrictions that must be observed before this examination. In fact, these restrictions are much less.
Blood for analysis does not have to be taken on an empty stomach. You can donate blood throughout the day. On this day you can eat and drink. But between the last meal and blood sampling for biochemical analysis, at least 3-4 hours should pass. On the eve, it is worth limiting only the intake of fatty foods. All other products are free to use.
On the eve, you can go in for sports in the usual load (the main thing is that there is no more physical activity than usual).
If you need a systematic intake of drugs, then they do not need to be canceled. But in the questionnaire that you will fill out, you indicate this.
If the blood test was preceded by stress or a cold, this also does not affect the result of the analysis.

To perform an ultrasound, you just need to be present. A full bladder is not required for fetal examination.
Therefore, the main recommendation for the correct conduct of the study and obtaining reliable results is to comply with the terms of the study (11th - 14th weeks). Do not eat for 3-4 hours before donating blood for a biochemical study and it is recommended to limit fatty foods the day before.

In obstetrics, pregnancy management involves multiple examinations of the pregnant woman and the fetus. How many times is screening done? Within 9 months, a woman needs to undergo a general examination three times at different times. It is carried out to assess the basic physiological and anatomical characteristics of the fetus and determine probable pathologies.

The first trimester of pregnancy lasts 14 weeks, by the end of this period the first scheduled examination is scheduled, consisting of a mandatory first ultrasound of the fetus and various laboratory blood tests.

Order No. 457 Min. Health R.F. from 2000 says that screening should be carried out for all pregnant women. Every woman has the opportunity to file a waiver. However, such an act can only speak of the illiteracy of the future mother and indicate a negligent attitude towards her baby.

How many risk factors are there that are considered a reason for mandatory prenatal screening? The main reason for the examination is:

age criterion: 35+;
the end of previous pregnancies with miscarriage or fetal fading;
professional hazards;
diagnosing chromosomal pathologies in the fetus in a previous pregnancy or the birth of a child with intrauterine malformations;
diseases of an infectious nature, transferred at the beginning of pregnancy;
taking drugs prohibited for pregnant women;
alcoholism, drug addiction;
diseases transmitted by heredity, both in the family of the mother and in the family of the father of the child;
close family ties between the parents of the baby.

Prenatal screening is very important for those women in whose family there were genetic diseases or who gave birth to a child with chromosomal abnormalities. Screening will make it possible to diagnose the pathologies of the current pregnancy, if necessary, prescribe its termination for medical reasons

Conducting a prenatal examination

When is the examination carried out? Primary prenatal screening is given at the end of the first trimester. The choice of time is due to the fact that by this moment most of the systems and organs of the unborn child have already been formed, and the diagnostician has the opportunity to assess the development of the fetus, to identify pathologies in a timely manner. At week 13, ultrasound diagnostics makes it possible to determine neural tube defects and gene pathologies in the embryo.

Ultrasound diagnostics as 1 stage of screening

What tests are included in the first trimester screening? Screening consists of several types of mandatory diagnostic procedures and tests. Ultrasound diagnosis of the fetus is the main diagnostic procedure of the first trimester. It is carried out in two ways: transvaginal, that is, the sensor is inserted into the vagina, or abdominal, that is, through the anterior abdominal wall.

Ultrasound screening of the 1st trimester allows you to determine the anatomical features of the child, the presence of all organs, assess their location and development. The main dimensional fetometric indicators, the characteristics of the correct development of the fetus are also evaluated, the neck fold, head girth, biparietal diameter, etc. are measured. It is mandatory to determine the size of the coccygeal-parietal size and, accordingly, the approximate height of the child at this stage of development. With the help of prenatal ultrasound diagnostics, the quality of the placental-umbilical cord blood flow is assessed, the work of the heart muscle is characterized. Including determine the thickness of the collar space in the fetus, the deviation of this indicator from normal values \u200b\u200bmay indicate a high probability of developing chromosomal pathologies.

The first ultrasound examination is indispensable in the management of pregnancy, because it gives the doctor the opportunity to take the first fetometric indicators, determine the level of fetal development, its compliance with the gestational age

Biochemical blood test as stage 2 of screening

Biochemical analysis of blood is carried out in the laboratory. With the help of biochemical blood testing, carried out at week 13, the level of the PAPP-A protein and the hCG hormone is established. This study is also called the "double test".

The main hormone that begins to form after fertilization of the egg is human chorionic gonadotropin. When the level of the hCG hormone is low, this indicates that there is a placental pathology. The content of the hormone in the blood above the norm indicates fetal chromosomal pathologies, or indicates a multiple pregnancy.

The level of plasma protein in a woman's blood can also indicate various abnormalities in the development of the embryo. When there is a significant decrease in the PAPP-A index, this indicates possible chromosomal abnormalities and other congenital genetic defects.

If the results of the first prenatal screening reveal a high probability of the existence of the described pathological conditions, additional diagnostic procedures are mandatory. The expectant mother is sent to the procedure for studying the properties of amniotic fluid - amniocentesis. The technique makes it possible to determine the presence of chromosomal pathologies and some genes. They also do chorionobiopsy, i.e. a biopsy of the chorionic villi is performed. To carry out the test, cells that form the placenta are taken, and with their help, prenatal and hereditary diseases are determined.

Preparatory stage of screening

The first screening study needs a preliminary preparatory stage. Prenatal examination at other stages of pregnancy does not require such careful preparation and is much easier.

What foods should not be consumed before the first screening? The day before research activities, it is recommended to limit the use of foods that are potential allergens. These are chocolate, citrus fruits, seafood, individual intolerance products. Doctors do not advise eating fried and fatty foods.

The first prenatal ultrasound is usually done transvaginally. This diagnostic technique does not require special training. If, according to indications, an abdominal examination is prescribed - an ultrasound scan performed through the skin of the abdomen, then it is necessary to drink a certain amount of clean water without gas in advance to completely fill the bladder (about 500 ml.).

Preparation for a biochemical blood test is quite simple. Screening is done in the morning on an empty stomach, so you should come to the laboratory without breakfast. In addition, it is recommended to perform standard hygiene measures before examinations, without using flavored cosmetic and hygiene products.

Normal test scores

At the first prenatal screening, a number of characteristics are determined and special attention is paid to their compliance with generally accepted standard norms:

Using an ultrasound examination, the thickness of the collar space (TVP) is assessed.
The size of the nasal bone. This indicator, as well as the value of TVP, allows you to make a timely diagnosis of Down syndrome. Before 11 weeks, this anatomical characteristic cannot yet be assessed, and at 13 weeks, the length of the nasal bone should be at least 3 mm.
A characteristic that depends on the degree of fetal development is the heart rate (HR). The dependence of heart rate on the week of pregnancy is shown in the table below.
Also on ultrasound, the value of the coccyx-parietal size (KTR) is determined and the value of the biparietal size (BPR) of the child's head is calculated.

At the first ultrasound, the doctor necessarily checks for the presence of the nasal bone, calculates the thickness of the collar zone, and also makes other fetometric measurements. This whole complex of studies and standards makes it possible to identify genetic abnormalities and developmental delays in the early stages.

The normative values of the indicators described above are presented in the summary table:

week of pregnancy	TVP, mm	KTR, mm	Heart rate, beats per minute	BPR, mm
10	1,5 - 2,2	31 – 41	161 – 179	14
11	1,6 - 2,4	42 – 49	153 – 177	17
12	1,6 - 2,5	52 – 62	150 – 174	20
13	1,7 - 2,7	63 – 74	147 – 171	26

Screening of the first trimester of pregnancy includes a mandatory biochemical determination of the amount of the hCG hormone. The normal values of this indicator in the female body correspond to the following values:

In addition to the above indicators, at the first prenatal screening, based on ultrasound data, it is imperative to assess the degree of development of the systems and organs of the unborn child. Using laboratory techniques for blood tests, determine the content of glucose and protein A.

Possible pathological conditions detected by examinations

With the help of ultrasound diagnostics carried out in the first trimester of pregnancy, important information can be obtained about the possible development of chromosomal abnormalities.

Ultrasound determines the likelihood of the existence of Down syndrome, de Lange, Patau syndrome, Edwards syndrome, anomalies in the formation of the nervous system, the appearance of an umbilical hernia and such a chromosomal anomaly as triplodia.

Screening data interpretation

When deciphering the data obtained from an ultrasound examination and a blood test, the doctor compares the results with standard normal values and calculates the probability of possible deviations. To do this, the specialist determines the coefficients that show the discrepancy between the received data and some standard values. Usually, the resulting coefficient is abbreviated MoM:

The normal value of MoM for the first 12 - 14 weeks ranges from 0.5 - 2.5. The best MoM is 1.
The MoM value calculated for the hCG indicator below 0.5 indicates a high risk of Edwards syndrome. MoM above 2.5 is considered a sign of the development of Down syndrome.

Based on the results of the examinations, the overall probability coefficient for the existence of serious genetic pathologies is calculated. If the value of the generalized coefficient at week 13 ranges from 1:251 to 1:399, such a survey result is considered poor, and in terms of hormone levels, coefficient values below 0.5 and more than 2.5 are considered negative indicators.

The development of two fetuses, a woman's overweight, diabetes mellitus, or other diseases of the endocrine system can affect the results of screening, and many characteristics may deviate from the normative values. Sometimes even the psychological state affects the reliability of the data obtained during the research.

Unwanted screening results should not be cause for serious distress. No matter how high the risk of developing pathology, there is the same high probability of having a healthy child.

During the first trimester of fetal development, many unique processes take place. During this period, the baby develops all the systems of internal organs. In order to timely diagnose various pathologies in such an important period, ultrasound screening is used.

What is it for?

The introduction of screening examinations in our country happened quite recently. This was facilitated by high maternal and infant mortality. In order to reduce these statistical indicators, specialists from the Ministry of Health have developed special recommendations. They provide for ultrasound several times during the entire period of pregnancy.

Every expectant mother will certainly be interested in the question of what screening is. Literally translated, this term means "screening". Screening identifies all pregnant women with pathological pregnancy. Expectant mothers who have been diagnosed with any disorders should be under more careful observation by doctors.

During this type of study, doctors determine both various developmental pathologies in a baby developing in the mother's womb, and concomitant diseases of the internal genital organs in the mother. This is done in one study.

If during the examination any deviations were revealed, then recommendations are given to the expectant mother be sure to attend the second and third screenings.

With the help of such an examination, you can also determine the sex of the unborn baby - this can be done, as a rule, at 11-12 weeks of pregnancy. Experienced ultrasound specialists can see the sex of the child earlier, but they often make mistakes.

There is no need to rush to find out who "lives" in the tummy.

The intrauterine development of the baby undergoes a series of successive stages. By the end of the first trimester, when the first formation of his genitals occurs, a study should be carried out to determine the sex.

An ultrasound scan performed during this period of pregnancy also allows calculate the due date more accurately. Usually this indicator is calculated in obstetric weeks. In this case, there is a definite difference between the gestational and obstetric period. In order to avoid confusion, experts recommend using the term "obstetric" gestational age.

The first trimester is not the best time to exclude all genetic and chromosomal diseases in the fetus. However, it should be noted that during this period some signs of these pathologies can be identified. To do this, doctors and scientists have developed a whole range of different ultrasound criteria that are used to draw up a conclusion. They help doctors in a timely manner to suspect that the baby has the first signs of genetic abnormalities.

Screening ultrasound can also detect certain violations of the uteroplacental blood flow. This method will allow you to determine the pathological narrowing or other abnormalities of the blood vessels that feed the fetus. If necessary, an auxiliary method called dopplerography can also be used. It allows you to determine various pathologies of blood flow more accurately. During the first ultrasound screening, specialists can also identify quite dangerous pathologies.

Rudimentary brain changes are an unfavorable clinical sign that requires timely diagnosis.

To determine the emerging pathologies at this stage of pregnancy, an expert-level ultrasound is sometimes required.

A screening test is a necessary clinical test to identify dangerous conditions, which can lead to the threat of miscarriage. Specialists with the help of special ultrasonic sensors look and identify various pathologies that contribute to the development of fetal hypoxia. This state is quite clearly visible when using high-resolution devices.

Deadlines

Doctors recommend mandatory screening for all expectant mothers, without exception. The second ultrasound screening study is also carried out, as a rule, for absolutely all expectant mothers. The third screening is usually prescribed for certain medical reasons in cases where it is really required.

To obtain more reliable results, experts recommend undergoing ultrasound screening at 11-13 weeks of pregnancy. Usually this study is supplemented by a number of biochemical tests, which are given 2-3 days before the ultrasound.

There are clinical situations where screening can be delayed by 1-2 weeks. However, the shift in the schedule for screening ultrasound must necessarily be agreed with the obstetrician-gynecologist.

Where can you do it?

The obstetrician-gynecologist who observes the expectant mother during the entire development of her pregnancy gives a referral for screening. This medical form indicates the personal data of the pregnant woman, the expected duration of pregnancy, and also makes various notes about her state of health. This direction also indicates the date and time of the ultrasound.

You can also get tested in a private clinic. A referral from a doctor is usually not required for this. A future mother can sign up for such a study on her own.

Prices for screening ultrasounds in private clinics vary. The average cost of such a study is 2000-4000 rubles. If the examination will be carried out on expert-class equipment or by a more qualified specialist, then this diagnostic procedure will cost a little more. In large cities, the cost of the first screening ultrasound sometimes reaches 8,000 rubles or more.

Proper preparation

To obtain reliable and accurate results of the study, the expectant mother should definitely carefully prepare for the screening. Usually, all recommendations are given to a woman at her next appointment with her obstetrician-gynecologist.

Basic training in the early stages of all pregnant women, as a rule, is the same for everyone. However, there may be slight differences. Usually they are associated with the filling of the bladder. Most women should not drink a lot of fluids immediately prior to a diagnostic procedure. Especially if the examination will be carried out by the transvaginal method.

However, there are a number of exceptions. In these cases, doctors recommend a few hours before the ultrasound drink about 0.5 liters of liquid. A water-filled bladder pushes the uterus forward, making it more accessible for visualization. This special training is not required for all women. If it is still necessary, then the doctor will definitely warn the expectant mother about this.

In the early stages of pregnancy, significant preparation is not required. Usually, to obtain accurate results of the study, doctors recommend expectant mothers to follow a special diet. In such a diet, all fatty and fried foods are limited.

Dinner on the eve of the diagnostic procedure should be as easy as possible. Breakfast before the morning ultrasound should not be. You can only drink a little water.

For expectant mothers with diabetes, especially with an uncontrolled course, such recommendations cannot be followed. Skipping the next breakfast can lead to a critical drop in blood sugar, which is extremely undesirable for both mom and her baby.

A few days before the screening test, pregnant women should exclude all fruits and vegetables from their menu. Also banned are any varieties of cabbage, legumes, kvass and any carbonated drinks. All of these products can lead to severe gas formation.

The intestines filled with gases will not allow the ultrasound specialist to conduct a full-fledged study. In this case, the ultrasound report that the woman will receive after the examination will contain the phrase about echonegativity.

Eating a lot of protein foods 2-3 days before the screening is not worth it. Such food, especially in large quantities, also contributes to bloating. Better to have food as light as possible, but high-calorie and nutritious. For this, lean poultry or white fish with a cereal side dish is perfect.

Exclusion of physical activity is a very important step in preparing for the procedure. Scientists have found that even the usual everyday activities that expectant mothers perform daily can lead to distorted results.

In order to minimize the risk of obtaining inaccurate test results, any physical activity should be limited. Future mothers should replace them with walks in the fresh air at a moderate pace. They will benefit not only the female body, but also the baby who is in her womb.

Any psycho-emotional stress also contributes to the disruption of metabolic processes in the body of a pregnant woman. Experts have long revealed one interesting fact: in suspicious and anxious pregnant women during an ultrasound the baby may turn away from the sensor or begin to actively move. In order to fully examine the fetus, doctors strongly recommend that pregnant women not be nervous or worried.

If during the bearing of the baby the expectant mother still continues to smoke, then on the eve of the study, the number of cigarettes smoked should be significantly limited. Doctors have found that nicotine and tar, which are contained in tobacco, cause a hypoxic state in the fetus. Also, these chemicals lead to a violation of the uteroplacental blood flow, which will be revealed on ultrasound.

Different methods

Screening studies are performed by ultrasound specialists. They have special training in this branch of medicine. It is better that the first screening is performed by a qualified and experienced doctor who has sufficient experience in conducting such studies.

This will somewhat reduce the risk of possible errors and making an incorrect conclusion after the survey. If, after the ultrasound, the obstetrician-gynecologist has any doubts about the unreliability of the results obtained, then he can refer the future mother for re-examination to another specialist.

There are certain situations when a screening test is not performed in a regular antenatal clinic. Expectant mothers with severe concomitant diseases of internal organs or gestation pathologies can be sent for examination to the perinatal center. The specialists of this medical institution will be able to more accurately and efficiently identify all the “hidden” pathologies or emerging anomalies in the intrauterine development of babies.

Currently, the study can be carried out in several ways. In the early stages, in most cases it is used transvaginal. The technique of this procedure involves the use of a special ultrasound probe inserted into the vagina. There is no need to be afraid of this type of examination. With the right technique, it will not cause a woman any soreness and discomfort.

The transvaginal method allows you to identify various pathologies in both the mother and the fetus quite effectively and accurately. There are a number of contraindications for this diagnostic procedure; it is not suitable for women with exacerbation of colpitis or vaginitis. In these situations, it is better to resort to an alternative method - transabdominal.

In this case, an ultrasonic sensor is used, with which the doctor drives along the "pregnant" tummy. This method is also an excellent way to diagnose various intrauterine developmental defects. Most expectant mothers prefer this particular method of ultrasound. As a rule, a screening study in this way is also carried out if during the diagnostic procedure, the patient's spouse is present.

To obtain a high-quality picture, a special diagnostic gel. It is transparent and slightly sticky to the touch. The gel is applied to the tummy of the expectant mother immediately before the procedure.

This substance helps ultrasonic waves to be better reflected and penetrate well into the internal environment of the body. The chemical composition of the gel is completely hypoallergenic and cannot cause allergic manifestations.

What to bring?

If the study will be carried out in a women's clinic, then the future mother should take a towel from the house. It will be needed in order to lay it on a special couch on which the study will be conducted.

The ultrasound is usually performed in the supine position. Only with certain pathologies of the uterus in a woman, the specialist conducting the study can ask her to turn on her left or right side. After the procedure, you may need paper napkins. They are necessary to remove the remnants of the gel from the abdomen.

If the study will be conducted in a private clinic, you do not need to take anything with you. All necessary things are already included in the cost of the procedure and will be provided. The doctor performing the ultrasound may ask for medical documentation. To do this, the expectant mother should not forget to take her card with her.

Evaluation of results

After the study, the doctor who conducted the screening examination will definitely issue his opinion. It will indicate only those changes that the doctor saw during the study. Also, in the conclusion, the dimensions of all the studied parameters that can be determined at this stage of pregnancy should be indicated.

Expectant mothers should remember that such a conclusion is not considered a diagnosis. It requires a mandatory interpretation of an obstetrician-gynecologist. Decoding can only be done by a doctor who observes the expectant mother and performs a clinical examination. It is he who determines the presence of pathologies and makes diagnoses.

In some cases, after the study, the doctor may refer the woman for additional additional examination. Usually in such a situation, some biochemical tests are performed. You may also need to consult a therapist or a "narrow" specialist.

Norms

To assess the intrauterine development of the fetus at this time, doctors use special ultrasound indicators. They were developed by scientists taking into account the peculiarities of the physiology and anatomy of the fetus. The use of these indicators helps specialists to suspect genetic and chromosomal pathologies in a timely manner, as well as to identify developmental anomalies in the baby in the early stages:

Coccyx-parietal size (KTP) is the baseline that is used in the first trimester prenatal study. Many experts prefer to use special tables in which the normal values \u200b\u200bof this indicator are entered. With the growth of the baby, this parameter increases. This indicates the normal course of pregnancy and the optimal intrauterine development of the fetus.

For a period of 11 weeks, this figure is 34-50 mm. It is important to note that these values are averages. By week 12, the values of this indicator are already increasing to 42-59 mm. After 7 obstetric days, the CTE becomes equal to 51-75 mm.

heartbeat is another measure to be measured. It shows how well the fetal heart muscle contracts. The baby's myocardium begins to work from the 6th week of its intrauterine development. This ensures that the doctor conducting the study can easily count the number of heartbeats in one minute. Normally, this figure by the 9th week of intrauterine development is already 130-140 per minute. Any deviations from normal values may indicate a problem in the child's body. In this case, additional diagnostics may be required. Heartbeat is a very important indicator that must be evaluated.

Collar space thickness- also a very important ultrasound - a criterion that allows you to determine various gross developmental defects. This indicator is used to predict the risk of various genetic indicators. At the 11th week of intrauterine development, this ultrasonic criterion becomes equal to 0.8-2.4. A week later, its values change to 0.7-2.7.
During the study, doctors can identify a rather dangerous condition called hypertonicity. It can lead to spontaneous miscarriage or threatened miscarriage. In this situation, the obstetrician-gynecologist will send the expectant mother for hospitalization. To normalize the tone of the uterus, complex therapy and normalization of the daily routine are required.

Screening of the 1st trimester is a diagnostic study that is carried out by pregnant women at risk from 10 to 14 weeks. Being the first of two screening observations, it allows you to determine with great accuracy how high the risk of having a sick fetus is. Such an examination consists of two parts - blood donation from a vein and ultrasound. Based on them, taking into account many of your individual factors, the geneticist makes his verdict.

Screening (from the English "screening") is a concept that includes a number of activities to detect and prevent diseases. For example, screening during pregnancy provides the doctor with complete information about the various risks of pathologies and complications in the development of the child. This makes it possible to take full measures in advance to prevent diseases, including the most severe ones.

Who needs 1st trimester screening

It is very important that the following women undergo the study:

consanguineous with the child's father
who have had 2 or more spontaneous abortions (premature births)
had a missed pregnancy or stillbirth
a woman had a viral or bacterial disease during pregnancy
have relatives suffering from genetic pathologies
this couple already has a child with Patau, Down syndrome or other
there was an episode of treatment with drugs that should not be used during pregnancy, even if they were prescribed for vital signs
pregnant over 35 years
both future parents want to check the probability of having an affected fetus.

What to look for at the first ultrasound screening during pregnancy

What is seen at the first screening? The length of the embryo is estimated (this is called the coccygeal-parietal size - KTP), the dimensions of the head (its circumference, biparietal diameter, the distance from the forehead to the back of the head).

The first screening shows the symmetry of the cerebral hemispheres, the presence of some of its structures, which are mandatory at this time. Look at 1 screening also:

long tubular bones, the length of the shoulder, femur, bones of the forearm and lower leg is measured
whether the stomach and heart are in certain places
the size of the heart and the vessels emanating from them
belly sizes.

What pathology does this examination reveal?

The first pregnancy screening is informative in terms of detecting:

pathology of the rudiment of the central nervous system - the neural tube
patau syndrome
omphalocele - umbilical hernia, when a different number of internal organs are outside the abdominal cavity, and in the hernial sac above the skin
down syndrome
triploidy (triple set of chromosomes instead of double)
Edwards syndrome
Smith-Opitz syndrome
de Lange syndrome.

Terms of the study

When should the first screening be done? The terms of diagnosis of the 1st trimester are very limited: from the first day of the 10th week to the 6th day of the 13th week. It is better to do the first screening in the middle of this range, at 11-12 weeks, since an error in the calculations significantly reduces the correctness of the calculation.

Your doctor should once again scrupulously and thoroughly, depending on the date of the last menstruation, calculate at what time you should do the first study of this kind.

How to prepare for research

Screening of the first trimester is carried out in two stages:

The first step is an ultrasound screening. If this is to be done transvaginally, no preparation is required. If in the abdominal way, then it is necessary that the bladder is full. To do this, you need to drink half a liter of water half an hour before the study. By the way, the second screening during pregnancy is carried out transabdominally, but it does not require preparation.
Biochemical screening. This word refers to the drawing of blood from a vein.

Given the two-stage nature of the study, preparation for the first study includes:

bladder filling – before 1 ultrasound screening
fasting at least 4 hours before blood sampling from a vein.

In addition, you need a diet before the diagnosis of the 1st trimester in order for the blood test to give an accurate result. It consists in excluding the intake of chocolate, seafood, meat and fatty foods the day before you plan to attend a screening ultrasound during pregnancy.

If you plan (and this is the best option for perinatal diagnostics of the 1st trimester) to undergo both ultrasound diagnostics and donate blood from a vein on the same day, you need to:

the whole previous day to deny yourself allergenic foods: citrus fruits, chocolate, seafood
exclude completely fatty and fried foods (1-3 days before the study)
before the study (usually blood is taken for screening for 12 weeks before 11:00) go to the toilet in the morning, then either do not urinate for 2-3 hours, or drink half a liter of water without gas an hour before the procedure. This is necessary if the study will be performed through the abdomen
if ultrasound diagnostics is done with a vaginal probe, then preparation for 1st trimester screening will not include filling the bladder.

How the study is done

How is a study for malformations done in the 1st trimester?

It, like the 12-week examination, consists of two stages:

Ultrasound screening during pregnancy. It can be performed both vaginally and through the abdomen. It feels no different from an ultrasound at 12 weeks. The difference is that it is performed by sonologists, who specialize specifically in prenatal diagnostics, using high-class equipment.
Blood sampling from a vein in the amount of 10 ml, which should be done on an empty stomach and in a specialized laboratory.

How is the screening diagnosis of the 1st trimester? First, you go through the first ultrasound during pregnancy. It is usually performed transvaginally.

Deciphering the results

1. Normal ultrasound data

Deciphering the first screening begins with the interpretation of ultrasound diagnostic data. Ultrasound rules:

Coccyx-parietal size (KTR) of the fetus

At screening at 10 weeks, this size is in the following range: from 33-41 mm on the first day of week 10 to 41-49 mm on day 6 of week 10.

Screening 11 weeks - KTR norm: 42-50 mm on the first day of the 11th week, 49-58 - on the 6th day.

During pregnancy of 12 weeks, this size is: 51-59 mm at 12 weeks exactly, 62-73 mm - on the last day of this period.

2. Thickness of collar area

Norms of ultrasound of the 1st trimester in relation to this most important marker of chromosomal pathologies:

at 10 weeks - 1.5-2.2 mm
screening 11 weeks is represented by the norm 1.6-2.4
at week 12, this figure is 1.6-2.5 mm
at 13 weeks - 1.7-2.7 mm.

3. Nasal bone

Deciphering ultrasound of the 1st trimester necessarily includes an assessment of the nasal bone. This is a marker due to which the development of Down syndrome can be assumed (for this, screening of the 1st trimester is done):

at 10-11 weeks, this bone should already be detected, but its size has not yet been estimated
screening at 12 weeks or a week later shows that this bone is at least 3 mm normal.

4. Heart rate

at 10 weeks - 161-179 beats per minute
at 11 weeks - 153-177
at 12 weeks - 150-174 beats per minute
at 13 weeks - 147-171 beats per minute.

5. Biparietal size

The first screening study during pregnancy evaluates this parameter depending on the term:

at 10 weeks - 14 mm
in 11 - 17 mm
screening at 12 weeks should show a result of at least 20 mm
at 13 weeks BPD is 26 mm on average.

According to the results of ultrasound of the 1st trimester, it is assessed whether there are any markers of fetal abnormalities. It also analyzes what period the development of the baby corresponds to. At the end, a conclusion is made whether the next screening ultrasound in the second trimester is necessary.

You can ask to have a 1st trimester ultrasound video recorded for you. You also have every right to receive a photo, that is, a printout of the image that is either the most successful (if everything is normal), or most clearly demonstrates the found pathology.

What hormone norms are determined by 1 screening

First trimester screening does not only evaluate the results of ultrasound diagnostics. The second, no less important stage, by which it is judged whether the fetus has serious defects, is a hormonal (or biochemical) assessment (or a blood test in the 1st trimester). Both of these steps constitute genetic screening.

1. Chorionic gonadotropin

This is the hormone that colors the second strip on a home pregnancy test. If the first trimester screening revealed a decrease in its level, this indicates a pathology of the placenta or an increased risk of Edwards syndrome.

Elevated hCG at the first screening may indicate an increased risk of developing Down syndrome in the fetus. Although with twins, this hormone is also significantly increased.

The first screening during pregnancy: the rate of this hormone in the blood (ng / ml):

Week 10: 25.80-181.60
11 weeks: 17.4-130.3
decoding of the perinatal study of the 1st trimester at week 12 regarding hCG shows the figure 13.4-128.5 is normal
at 13 weeks: 14.2-114.8.

2. Pregnancy-associated protein A (PAPP-A)

This protein is normally produced by the placenta. Its concentration in the blood increases with increasing gestational age.

How to make sense of the data

The program, into which the data of ultrasound diagnostics of the first trimester, as well as the level of the two above hormones, is entered, calculates the analysis indicators. They are called "risks". At the same time, the transcript of the results of screening for the 1st trimester is written in the form not in the level of hormones, but in such an indicator as “MoM”. This is a coefficient that shows the deviation of the value for a given pregnant woman from a certain calculated median.

To calculate MoM, divide the indicator of a particular hormone by the median value calculated for a given area for a given gestational age. MoM norms at the first screening are from 0.5 to 2.5 (for twins, triplets - up to 3.5). The ideal MoM value is close to "1".

Are there any risks in the study

Normally, the results of the diagnosis of the 1st trimester end with a risk assessment, which is expressed as a fraction (for example, 1:360 for Down syndrome) for each syndrome. It is this fraction that reads like this: in 360 pregnancies with the same screening results, only 1 baby is born with Down's pathology.

Deciphering the norms of screening of the 1st trimester. If the child is healthy, the risk should be low and the screening test result should be described as "negative". All numbers after the fraction must be large (greater than 1:380).

A poor first screening is characterized by a high-risk report, a level of 1:250-1:380, and hormone results of less than 0.5 or more than 2.5 median values.

If the 1st trimester screening is poor, you are asked to visit a geneticist who decides what to do:

appoint you a second study in the second, then screening for the 3rd trimester
offer (or even insist) on an invasive diagnosis (chorionic villus biopsy, cordocentesis, amniocentesis), on the basis of which the question will be decided whether this pregnancy should be prolonged.

What influences the results

As with any study, there are false-positive results from the first perinatal study. So, when:

IVF: hCG results will be higher, PAPP - lower by 10-15%, first screening ultrasound results will increase LZR
obesity of the expectant mother: in this case, the levels of all hormones increase, while with low body weight, on the contrary, they decrease
1st trimester screening for twins: normal outcomes for such pregnancies are not yet known. Therefore, risk assessment is difficult; Only ultrasound diagnostics is possible
diabetes mellitus: 1st screening will show a decrease in hormone levels, which is not reliable for interpreting the result. In this case, pregnancy screening may be canceled.
amniocentesis: the rate of perinatal diagnosis is not known if the manipulation was carried out within the next week before blood donation. It is necessary to wait a longer period after amniocentesis before undergoing the first perinatal screening of pregnant women.
psychological state of the pregnant woman. Many write: "I'm afraid of the first screening." This can also affect the result, and unpredictably.

Some features in pathology

The first pregnancy screening for fetal pathology has some features that ultrasound doctors see. Consider perinatal screening of trisomies as the most common pathologies detected by this survey.

1. Down syndrome

most fetuses do not see the nasal bone at 10-14 weeks
from 15 to 20 weeks this bone is already visualized, but it is shorter than normal
smoothed facial contours
with dopplerometry (in this case it is possible to carry out it even at this time), a reverse or other pathological blood flow in the venous duct is noted.

2. Edwards syndrome

tendency to decrease heart rate
have an umbilical hernia (omphalocele)
no visible bones of the nose
instead of 2 umbilical arteries - one

3. Patau Syndrome

almost everyone has a rapid heartbeat
impaired brain development
the development of the fetus is slowed down (discrepancy between the length of the bones for the term)
impaired development of certain parts of the brain
umbilical hernia.

Where to take the study

Where is 1st trimester screening done? Many perinatal centers, medical genetic consultations and private clinics are involved in this study. To choose where to get screened, see if there is a laboratory in the clinic itself or near it. It is recommended to take it in such clinics and centers.

For example, in Moscow, the CIR has proven itself well: it also conducts screening of the 1st trimester at this Center.

Ultrasound screening of the 1st trimester: the average price is 2000 rubles. The cost of the first perinatal examination (with the determination of hormones) is about 4000-4100 rubles.

How much does screening for the 1st trimester cost by type of analysis: ultrasound - 2000 rubles, hCG determination - 780 rubles, analysis for PAPP-A - 950 rubles.

The main purpose of the first screening during pregnancy is to detect congenital fetal malformations at an early stage. Screening results are obtained from different patterns of blood tests and ultrasound. The individual characteristics of the woman (age, weight, bad habits (if any), hormone therapy (if any) are taken into account).

The first screening or, as it is also called, the first trimester screening is a comprehensive examination.

It is carried out by examination of venous blood and ultrasound examination between the eleventh and fourteenth weeks of pregnancy. The first screening allows you to determine the level of risk of pathological fetal changes. It is aimed, first of all, at identifying such defects as Down syndrome and Edwards syndrome, that is, the most gross and uncorrectable violations in genetics, as well as at identifying malformations in other organs and systems of the fetal body.

Ultrasound examination of the first screening

With the help of the first ultrasound examination of a pregnant woman, the physique of the future baby is determined, it turns out whether all the organs are in place, their correct location. In this case, various measurements are also made (for example, cervical crease, head circumference, distance from the occiput to the forehead, biparietal diameter, and so on). Be sure to look and measure the coccyx-parietal size, and the growth of the embryo.

Ultrasound examination of the first screening allows the doctor to examine the fetal blood flow, the work of his heart and determine the correspondence of the body length of the fetus to the gestational age.

Also in this study, the thickness of the collar space in the embryo is determined. And if its value deviates from the norm, the level of risk of genetic diseases increases.

First screening venous blood test

When analyzing blood from a vein in the first trimester of pregnancy, the content of plasma protein (PAPP-A) and is determined. This analysis is called in medicine a double test.

Human chorionic gonadotropin is the main hormone of pregnancy. With a reduced level, that is, a deviation from the norm to the lower side, indicates a placental pathology. With a deviation towards an increase in the level of this hormone in the blood, it is usually due to chromosomal fetal disorders or multiple pregnancy.

The plasma protein test measures the level of A-protein in the blood. If its level is significantly reduced in the blood of a pregnant woman, this indicates a risk of such abnormalities as Down syndrome, Edwards syndrome and other congenital fetal malformations.

If, based on the results of screening of the first trimester, a high level of risk of the above pathologies is determined, additional diagnostics are mandatory. The woman is sent for amniocentesis, that is, for the study of amniotic fluid. This test allows you to diagnose chromosomal and certain gene pathologies. Then the woman is sent for a chorionbiopsy, that is, a biopsy of the chorionic villi. For this study, cells are obtained that form, which are studied for congenital and hereditary fetal diseases.

What else is found out at the first screening?

In addition to all of the above, screening of the first trimester provides data on the symmetry of the cerebral hemispheres of the fetus, on the presence of certain structures that should form by this time. At the first screening, an assessment is made of the correct location of the internal organs of the child: stomach, heart, blood vessels. The length of the lower leg, forearm, femur and humerus bones, as well as the length of the tubular bones of the fetus, are measured.

What pathologies can be detected at the first screening?

The first screening can provide information about the following pathologies, which are likely to develop in this case:

de Lange's syndrome;
Smith-Opitz syndrome;
Patau syndrome;
pathology of the formation of the neural tube;
Edwards syndrome;
umbilical hernia or omphalocele (at the same time, ultrasound in the results gives a picture that clearly shows the location of the internal organs not in the abdominal cavity, but in the hernial sac, above the skin);
a triple set of chromosomes (instead of a double one), that is, triploidy.

How to prepare for this study?

The first screening is carried out in two stages - an ultrasound examination and a blood test from a vein.

May be transvaginal in the first trimester. In this case, preparation is not required at all. If the ultrasound is performed abdominally, that is, through the outer wall of the peritoneum, for this you need to fill your bladder. Before starting the study, you need to drink a lot of water (clean, non-carbonated), up to two liters.

The second stage of the study - blood is taken from a vein - this stage is called biochemical screening. Blood sampling is carried out on an empty stomach. Nothing should be taken from food for at least four hours.

It is advisable to follow a diet for several days before the first screening. This is important for the accuracy of the blood test. A couple of days before the start of the study, chocolate, meat, seafood, fatty foods should be excluded from the diet of a pregnant woman.

Timing of the first screening

There are time limits for first trimester screening. This study is carried out between the first day of the tenth week of pregnancy and the fifth day of the thirteenth week of the term.

The most optimal time for its implementation is the middle of the indicated period. The exact date should be calculated by the doctor who prescribes the screening and leads the pregnancy.

Who is screened for the first trimester?

The first screening is not mandatory for all pregnant women. It is carried out only with those expectant mothers who are at risk of any pathologies. This group usually includes women:

after the age of thirty-five;
those who have hereditary diseases in the family;
mothers with viral diseases transferred at an early stage of pregnancy;
those who had earlier miscarriages and terminations of pregnancy;
those who have had cases of fetal fading or stillbirth;
those women whose husband is a relative;
those who use drugs and other drugs prohibited during pregnancy;
those who have already had children with genetic pathologies and abnormalities;
and those who just want to have complete confidence that everything is in order with the child.

What can affect the results?

The first screening can give false results for several reasons:

when diagnosing obesity in a pregnant woman. In this case, the level of hormones will be significantly overestimated;
at . Protein in this case will be ten to fifteen percent lower, human chorionic gonadotropin is overestimated, and ultrasound will show an increase in LZR;
in multiple pregnancies (to date, there are no established norms for first screening indicators for multiple pregnancies0;
the psychological mood of the expectant mother (panic fear of all studies can lead to false results);
with amniocentesis. If the manipulation is carried out within seven days before venous blood sampling for screening, then the rate of perinatal diagnosis in this case is not known;
with diabetes. In this case, the first screening will show an underestimated level of human chorionic gonadotropin.