Decoding of biochemical screening of the 1st trimester of the blood norm. When is the first pregnancy screening done? Deciphering the analysis for free estriol

Prenatal or 1st trimester screening - what is this procedure? How does it go and what does it show? These questions are often asked by expectant mothers on the eve of the examination.

Screening is just a diagnosis that is carried out in order to identify possible pathologies, disorders and genetic abnormalities of the intrauterine development of a child. The deadline for the appointment of the procedure is not earlier than 11 weeks. It is mandatory to pass it up to 13 weeks and 6 subsequent days during pregnancy:

• the age of the future mother is more than 35 years;
• cases of fetal fading;
• miscarriages;
• infectious and inflammatory past diseases;
• possible genetic risk of complications, existing pathologies of the previous fetus;
• family ties between parents;
• the presence in the family of cases of alcoholism, drug addiction, smoking;
• work in hazardous production;
• taking illegal drugs.

The very first screening is carried out in accordance with the decree of the Ministry of Health. At what week it is necessary to do it is decided by the gynecologist. Usually no later than 13 expected weeks. The scheduled screening of the 1st trimester includes an ultrasound scan, a blood test, and a thorough biochemical analysis of its composition.

Diagnosis at the first ultrasound

Usually performed when fertilization is suspected. Already from the second week of the alleged menstruation delay, an ultrasound examination shows the presence of pregnancy, the approximate timing of the fetus, its development and possible diseases or disorders. It passes abdominally, that is, the abdominal wall is used for research, without insertion into the vagina. Required preparation:

• diet. Approximately 3 days before the scheduled study. Do not eat legumes, cabbage, carbonated drinks, bakery products, fruits before ultrasound;
• filled bladder. 3 hours before the ultrasound, you can not urinate;
• carried out strictly on an empty stomach. You can not eat food 4 hours before the diagnosis.

Less commonly, a transvaginal or pelvic ultrasound may be done. More informative. Diagnosis takes place with the introduction of an ultrasound probe into the vagina. Preparation and special diet is not required. Screening indicators during pregnancy in the first weeks:

• position of the uterus. Meaning "anteflexio";
• contours. Should be defined as equal;
• uterus dimensions: 70mm x 60mm x 40mm. Correspond to length, width, diameter;
• walls. Echogenicity is homogeneous;
• fertile egg. Diameter up to 5 mm or more, depending on the period;
• decidualization of the endometrium. Indicates the onset of pregnancy;
• the uterine cavity is homogeneous;
• ovary sizes. Width, length and thickness correspond to the values: 25mm x 30mm x 15mm.

Usually, such an examination is included in a regular medical examination. Not always a gynecologist can determine pregnancy on their own. If the pregnancy test shows a positive result, further diagnosis is carried out in the early stages. It is impossible to do an ultrasound earlier than 1.5-2 weeks after a delay in menstruation.

Ultrasound at 12 weeks

Appointed by a gynecologist. It is carried out within the clinic by specialists from 11 to 13 weeks. To determine pathologies and disorders of fetal development and pregnancy. Preparation required:

• diet. For 3 days, the complete exclusion of sweets, chocolate, seafood, fatty foods, legumes and cabbage;
• do not urinate 2-3 hours before the study. When conducting abdominal, external ultrasound.

In a timely manner, ultrasound shows the possible genetic risk of having an affected child. Further study of the problem is required. The first weeks of childbearing are very important. The norm of the following values ​​should be indicated in the results:

• embryo size. The measurement is taken from the head to the coccyx. KTP indicator;
• temple to temple distance. BPR data;
• thickness, density of the collar space, TVP;
• calculation of heart contractions and their frequency, heart rate.

To find out the sex of the child through ultrasound at week 12 is the dream of all future parents. But it cannot be determined exactly. There are too many mistakes on the part of doctors. It is better in this case to conduct an ultrasound at the 16th week of fetal development.

Norm and interpretation of results

Many patients specify which week is best for ultrasound screening. If there is data from a previous ultrasound, the exact dates are assigned, which suggest 12 weeks of pregnancy. In other cases, the timing shows a gynecological examination. The norm and interpretation of the results of the first ultrasound should have indicators:

• 10 weeks. KTR 33 - 41 mm. TVP up to 2.2 mm. The nasal bone is visible. The heart rate is 161-179 beats. BPR 14 mm;
• 11 weeks. KTR up to 50 mm. TVP - up to 2.4 mm. The nasal bone is visualized. Heart rate - 153 - 177. BDP 17 mm;
• 12 weeks. KTR up to 59 mm. TVP up to 2.5 mm. The nasal bone is more than 3 mm. The heart rate is 150-174. BPR 20 mm;
• 13 weeks. KTP not more than 73 mm. TVP up to 2.7 mm. Nasal bone more than 3 mm. Heartbeat - 147-171. BPR 26 mm.

In addition to these data, the circumference of the baby's head, the structure of the brain, the distance from the bones: frontal and occipital are determined. The forearms, pelvis and thigh bones are visible. Dimensions of the heart, ventricles. The doctor takes into account the amniotic fluid, the thickness of the placenta. Poor ultrasound results are also possible, which indicate the genetic risk of developing a sick fetus and the corresponding syndromes:

• Down. TVP or collar skin fold on the baby's neck has a width of up to 2.8. It is filled with liquid. With Down's syndrome, the liquid is dark in color. The nasal bone is shortened, the distance between the eyes is increased, tachycardia and heart pathologies are observed;
• Edwards. There is bradycardia or a decrease in heart rate in the fetus, there is no nasal bone, only one artery is observed in the umbilical cord, a hernia of the abdominal cavity;
• Patau. Bladder enlargement, tachycardia, impaired brain formation;
• Turner. The fetus has a rapid unnatural heartbeat, a developmental delay corresponding to 8 weeks of pregnancy;
• Smith-Lemli-Opitz. Hereditary genetic disease. The reason is a violation of cholesterol metabolism. It is characterized by mutations, craniofacial anomalies, neurological abnormalities;
• de Lange. A disease in which the genetic risk factor is 25%. The condition is possible mutations in the parents. In the fetus, a false-positive result is 5%;
• triploidy. Lack of division into the corresponding parts of the brain, holoprosencephaly. Decreased heart rate, bradycardia. Omphalocele, or misalignment of the abdominal organs. An increase in the pelvis of the kidneys and more than two cysts in the region of the skull.

For further examination, blood is taken from the pregnant woman, as well as taking samples from the fetus. If at least one of the above violations is found, the pregnancy is terminated. That is why screening is so important. Any deviation from the norm raises the suspicion of a specialist.

Biochemical screening

This examination must be done immediately after the ultrasound diagnosis. What is it: biochemical screening? When the gestational age is revealed, all indicators of fetal development are indicated, it is necessary to conduct a biochemical blood test or genetic screening. How is the preparation going:

• exclusion from the diet of foods that cause allergies. Chocolate, smoked products, seafood;
• a ban on fatty foods;
• analysis strictly on an empty stomach. It is forbidden to drink even water.

It is advisable to study the hormonal composition of the blood on the same day as the ultrasound examination. Then the doctor will be able to objectively evaluate the results and the data obtained. The norms of the biochemical composition of blood are considered according to three indicators. These values ​​are: human chorionic gonadotropin β-hCG, PAPP-A protein and MoM.

Biochemical screening results: β-hCG data

It appears as a second strip when passing a regular pregnancy test at home. HCG indicators are ambiguous. If it is elevated in the blood, it is possible that future parents should expect twins. Deciphering the results of β-hCG in ng / ml:

• 10 weeks from 25.8 to 181.6;
• 11 weeks from 17.4 to 130.4;
• 12 weeks from 13.4 to 128.5;
• 13 weeks from 14.2 to 114.7.

If beta-hCG is elevated at any stage, the fetus may develop Down syndrome, and the mother has diabetes or toxicosis. A decrease in the rate of β-hCG warns of a possible pathology, such as Edwards syndrome, the risk of miscarriage, placental insufficiency, or ectopic pregnancy. Up to 12 weeks, this hormone increases, but within the normal range. After - it goes down.

PAPP-A norm at 12 weeks

A protein, protein-A, which is produced during pregnancy by the placenta. It indicates the normal course of fetal development. If PAPP-A is elevated, a woman may have a pregnancy failure or miscarriage. A decrease in protein indicates genetic diseases. Indicators of the PAPP-A norm in the blood:

• 10-11 weeks. PAPP-A from 0.45 mU/ml to 3.73 mU/ml;
• 11-12 weeks. PAPP-A from 0.78 mU/ml to 4.77 mU/ml;
• 12-13 weeks. PAPP-A from 1.03 mU/ml to 6.02 mU/ml
• 13-14 weeks. PAPP-A from 1.47 mU/ml to 8.55 mU/ml.

Low rates are a genetic risk of pathologies. Diseases like Down syndrome, Edwards, de Lange. This analysis is only valid up to 14 weeks. In the second trimester, it becomes uninformative.

After all the data received, the doctor calculates the coefficient of deviation from the norm, MoM. It usually ranges from 0.5 to 2.5. If it is exceeded to a value of 3.5, then there are several embryos. The final form of the result can be "positive" for pathology and "negative". The follow-up examination will take place already in the 2nd trimester.

The approximate cost of this procedure depends on the location of the procedure. Prenatal type of diagnosis will cost 1600 rubles. The difference between ultrasound and biochemical blood sampling for research should not be more than 5 days. You must have all the data from previous examinations with you.

1st trimester screening: what diagnostics should show

Content

A referral for a screening examination causes panic among expectant mothers. A lot of questions arise - what is it, is it dangerous for the baby, why are they sending me? In order not to worry unnecessarily in such a crucial period, it is better to deal with this issue in advance.

What is screening

For women who are expecting a baby, the Ministry of Health recommends that they undergo examinations in the first trimester in order to identify abnormalities in the growth of the fetus in the early stages. Perinatal testing does not appear to be threatening for a mother with a child. The price of the study is affordable, so you should not risk the life of the unborn baby. Screening during pregnancy helps to identify:

• genetic pathologies;
• indirect signs of violations;
• fetal malformations.

Be sure to do screening during pregnancy in the 1st trimester of all who are at risk. These are women who have:

• the father of the child who received radiation;
• age category over 35 years;
• threat of abortion;
• hereditary diseases;
• professional hazard;
• children born with pathologies;
• previous missed pregnancy, miscarriages;
• relationship with the father of the child;
• drug, alcohol addiction.

First screening during pregnancy

It is important to conduct a screening test for the first time if the price of the issue is the life of the unborn baby. What can be revealed during the examination? First trimester screening can detect:

• defects of the central nervous system;
• genetic diseases - Edwards syndrome, Down syndrome;
• the presence of an umbilical hernia;
• slow growth of the bones of the skeleton;
• violations of the formation of the brain;
• quickening or slowing of the heartbeat;
• one umbilical artery (should be two).

What is seen at the first screening

An important component of the calm state of the mother and confidence in the correct development of the baby are screenings during pregnancy. Important parameters of the fetus are measured during the first ultrasound examination:

• the size between the parietal tubercles;
• TVP - thickness dimension of the collar space;
• KTR size - from the coccyx to the bone on the crown of the head;
• bone length - forearm, thigh, lower leg, shoulder;
• heart size;
• Head circumference;
• vessel sizes;
• the distance between the frontal, occipital bones;
• heart rate.

First screening during pregnancy - timing

What determines the time of the first screening study? An important indicator in the fetus is the thickness of the collar space. The period when the first screening is done is at the beginning of the 11th week, earlier the TST value is too small. The end of the period is associated with the formation of the fetal lymphatic system. After 14 weeks, the space is filled with fluid, it can increase, as in pathology - and the results will not be objective. The end of the term is considered to be 13 weeks plus an additional 6 days.

Preparing for 1st trimester screening

Ultrasound examination does not involve preparation if the examination is carried out through the vagina. When checking through the abdominal wall, it is required to fill the bladder with three glasses of water 1.5 hours before starting. How to prepare for the screening of the 1st trimester, its second component - a blood test? To obtain an objective result, you need:

• two days before do not eat seafood, nuts, chocolate, smoked and fried foods;
• in the morning on the day of the event, do not drink anything;
• donate blood on an empty stomach.

How is the first pregnancy screening done?

Wishing to exclude defects, to determine inconsistencies in the development of the fetus, women in the first trimester are sent for examination. After deciphering the results, comparing them with the standards, a decision is made. With poor performance, abortion is possible. How is the 1st trimester screening going? The research includes two stages:

• ultrasound examination, in which measurements of the fetus are made, the characteristics of its vital activity, the condition of the uterus are established;
• biochemical analysis of maternal blood, revealing the absence of chromosomal defects.

The first screening during pregnancy - the norm

After the study, the resulting indicators are compared with the standards. An important point is the dependence of these values ​​​​on the correct gestational age: at what exact week the check was carried out. The 1st trimester screening rates for ultrasound results are:

• coccyx-parietal size - 34-75 mm;
• present, not measured at a period of 11, 12 weeks, the nasal bone, further, the value exceeds 3 millimeters;
• heart rate - 147-178 beats per minute;
• the size between the parietal bones is 13-28 mm;
• the thickness of the collar space is in the zone of 0.8 - 2.7 mm.

Biochemical hemoanalysis has its own standards. They are influenced by the week of the study. After receiving the results, the MoM coefficient is calculated using a computer, showing deviations in the development of the fetus. The parameters are proportionate to the term:

• beta hCG - 14.2-130.9 ng / ml;
• design coefficient MoM - 0.51-2.5;
• PAPP-A - 046- 8.53 mU / ml.

Ultrasound screening of the 1st trimester

The main examination of this period is ultrasound. Based on its results (with fears of chromosomal defects), blood tests are prescribed. Screening ultrasound of the 1st trimester checks the fetus, in addition to measuring parameters:

• structure and symmetry of the brain;
• blood flow of the venous duct;
• the presence of an umbilical hernia;
• position of the stomach, heart;
• the number of umbilical vessels.

During the screening study, measurements and monitoring of the condition of the pregnant woman are carried out. The indicators will tell you about the threats to the development of the fetus. An increased tone of the uterus can provoke a spontaneous abortion. During an ultrasound examination, a woman determines:

• location, thickness of the placenta;
• uterine tone;
• the amount of amniotic fluid;
• picture of the cervical os.

Biochemical screening

If abnormalities are detected during ultrasound, blood tests are prescribed to clarify the threat of chromosomal pathologies. The results are interconnected with the timing, accurately determined by ultrasound examination. Maternal venous blood serum is taken for analysis. Based on the results, the risk of anomalies is calculated. Gemotest determines 2 parameters that are compared with the standard:

• free beta subunit of hCG;
• plasma protein A - PAPP-A.

Screening of the 1st trimester - interpretation of the results

Specialists with the help of computer processing after the research make a decoding of the research. The results of screening of the 1st trimester depend on the week in which they are carried out, they have different indicators. When performing an ultrasound:

• determine the presence and size of the nasal bone - more than 3 millimeters;
• measure the thickness of the collar space - an increased indicator indicates the likelihood of pathology.

The interpretation of the results of blood biochemistry is also associated with the week in which:

• indicators of beta-hCG below the standard - the likelihood of an ectopic, missed abortion, miscarriage;
• the results are high - toxicosis, the presence of several fetuses, tumors, Down syndrome are possible;
• PAPP-A values ​​\u200b\u200bare more than normal - the threat of termination, missed pregnancy;
Video guide Week 11 First trimester screening 001

Almost every pregnant woman has heard something about screening for the first trimester of pregnancy (prenatal screening). But often even those who have already passed it do not know what exactly it is prescribed for.

And for expectant mothers who have yet to do this, this phrase in general sometimes seems frightening. And it frightens only because the woman does not know how it is done, how to interpret the results obtained later, why the doctor needs it. You will find answers to these and many other questions related to this topic in this article.

So, more than once I had to deal with the fact that a woman, having heard an incomprehensible and unfamiliar word screening, began to draw terrible pictures in her head that frightened her, making her want to refuse to carry out this procedure. Therefore, the first thing we will tell you is what the word “screening” means.

Screening (English screening - sorting) - these are various research methods that, due to their simplicity, safety and availability, can be used massively in large groups of people to identify a number of signs. Prenatal means prenatal. Thus, we can give the following definition of the concept of "prenatal screening".

Screening of the first trimester of pregnancy is a set of diagnostic studies used in pregnant women at a certain stage of pregnancy to detect gross malformations of the fetus, as well as the presence or absence of indirect signs of fetal pathologies or genetic abnormalities.

The allowable period for 1st trimester screening is 11 weeks - 13 weeks and 6 days (see). Screening is not carried out earlier or later, as in this case the results obtained will not be informative and reliable. The most optimal period is considered to be 11-13 obstetric weeks of pregnancy.

Who is referred for first trimester screening?

According to Order No. 457 of the Ministry of Health of the Russian Federation of 2000, prenatal screening is recommended for all women. A woman can refuse it, no one will forcibly lead her to these studies, but doing this is extremely reckless and speaks only of the woman's illiteracy and negligent attitude towards herself and, above all, towards her child.

Risk groups for whom prenatal screening should be mandatory:

• Women who are 35 years of age or older.
• The presence of a threat of termination of pregnancy in the early stages.
• Spontaneous (e) miscarriage(s) in history.
• Frozen (s) or regressing (and e) pregnancy (s) in history.
• The presence of occupational hazards.
• Previously diagnosed chromosomal abnormalities and (or) fetal malformations based on screening results in past pregnancies, or the presence of children born with such anomalies.
• Women who have had an infectious disease in early pregnancy.
• Women who took drugs that are prohibited for pregnant women in the early stages of pregnancy.
• The presence of alcoholism, drug addiction.
• Hereditary diseases in the family of a woman or in the family of the child's father.
• I am closely related to the relationship between the mother and father of the child.

Prenatal screening at 11-13 weeks of gestation consists of two research methods - ultrasound screening of the 1st trimester and biochemical screening.

Screening Ultrasound

Preparation for the study: If the ultrasound is performed transvaginally (the probe is inserted into the vagina), then no special preparation is required. If ultrasound is performed transabdominally (the sensor is in contact with the anterior abdominal wall), then the study is performed with a full bladder. To do this, it is recommended not to urinate 3-4 hours before it, or one and a half hours before the study, drink 500-600 ml of water without gas.

Necessary conditions for obtaining reliable ultrasound data. According to the norms, screening of the first trimester in the form of ultrasound is carried out:

• Not earlier than 11 obstetric weeks and not later than 13 weeks and 6 days.
• KTR (coccyx-parietal size) of the fetus is not less than 45 mm.
• The position of the child should allow the doctor to adequately take all measurements, otherwise, it is necessary to cough, move, walk for a while so that the fetus changes its position.

As a result of ultrasound the following indicators are studied:

• KTR (coccygeal-parietal size) - measured from the parietal bone to the coccyx
• Head circumference
• BDP (biparietal size) - the distance between the parietal tubercles
• Distance from frontal bone to occipital bone
• Symmetry of the cerebral hemispheres and its structure
• TVP (collar space thickness)
• HR (heart rate) of the fetus
• The length of the humerus, femur, as well as the bones of the forearm and lower leg
• Location of the heart and stomach in the fetus
• Dimensions of the heart and great vessels
• The location of the placenta and its thickness
• Number of waters
• The number of vessels in the umbilical cord
• Condition of the internal cervical os
• Presence or absence of uterine hypertonicity

Decryption of the received data:

What pathologies can be detected as a result of ultrasound?

According to the results of ultrasound screening of the 1st trimester, we can talk about the absence or presence of the following anomalies:

• Trisomy 21 is the most common genetic disorder. The prevalence of detection is 1:700 cases. Thanks to prenatal screening, the birth rate of children with Down syndrome has decreased to 1:1100 cases.
• Neural tube pathologies(meningocele, meningomyelocele, encephalocele and others).
• Omphalocele is a pathology in which part of the internal organs is located under the skin of the anterior abdominal wall in a hernial sac.
• Patau's syndrome is a trisomy of chromosome 13. The frequency of occurrence is on average 1:10,000 cases. 95% of children born with this syndrome die within a few months due to severe damage to the internal organs. On ultrasound - rapid fetal heart rate, impaired brain development, omphalocele, slowing down the development of tubular bones.
• Trisomy 18 chromosome. The frequency of occurrence is 1:7000 cases. It is more common in children whose mothers are older than 35. On ultrasound, there is a decrease in the fetal heartbeat, an omphalocele, nasal bones are not visible, one umbilical artery instead of two.
• Triploidy is a genetic anomaly in which there is a triple set of chromosomes instead of a double set. Accompanied by multiple malformations in the fetus.
• Cornelia de Lange syndrome- a genetic anomaly in which the fetus has various malformations, and in the future, mental retardation. The incidence rate is 1:10,000 cases.
• Smith-Opitz syndrome- an autosomal recessive genetic disease, manifested by a metabolic disorder. As a result, the child has multiple pathologies, mental retardation, autism and other symptoms. The frequency of occurrence is on average 1:30,000 cases.

More about diagnosing Down syndrome

Mostly, an ultrasound scan at 11-13 weeks of gestation is performed to detect Down syndrome. The main indicator for diagnosis is:

• The thickness of the collar space (TVP). TVP is the distance between the soft tissues of the neck and the skin. An increase in the thickness of the collar space may indicate not only an increased risk of having a child with Down syndrome, but also that other genetic pathologies in the fetus are possible.
• In children with Down syndrome, most often for a period of 11-14 weeks, the nasal bone is not visualized. The contours of the face are smoothed.

Before 11 weeks of gestation, the thickness of the collar space is so small that it cannot be adequately and reliably assessed. After 14 weeks, the lymphatic system is formed in the fetus and this space can normally be filled with lymph, so the measurement is also not reliable. The frequency of occurrence of chromosomal abnormalities in the fetus, depending on the thickness of the collar space.

When deciphering the screening data of the 1st trimester, it should be remembered that the thickness of the collar space alone is not a guide to action and does not indicate a 100% probability of a child having a disease.

Therefore, the next stage of screening of the 1st trimester is carried out - taking blood to determine the level of β-hCG and PAPP-A. Based on the obtained indicators, the risk of chromosomal pathology is calculated. If the risk according to the results of these studies is high, then an amniocentesis is suggested. This is the taking of amniotic fluid for a more accurate diagnosis.

In particularly difficult cases, cordocentesis may be required - taking cord blood for analysis. A chorionic villus biopsy may also be used. All of these methods are invasive and carry risks for the mother and fetus. Therefore, the decision to conduct them is decided by the woman and her doctor jointly, taking into account all the risks of conducting and refusing the procedure.

Biochemical screening of the first trimester of pregnancy

This stage of the study is carried out necessarily after ultrasound. This is an important condition, because all biochemical parameters depend on the gestational age up to the day. Every day the standards change. And ultrasound allows you to determine the gestational age with the accuracy that is necessary for a proper study. At the time of blood donation, you should already have the results of an ultrasound scan with the indicated gestational age based on the KTP. Also, an ultrasound scan may reveal a frozen pregnancy, a regressing pregnancy, in which case further examination does not make sense.

Study preparation

Blood is taken on an empty stomach! It is undesirable even to drink water in the morning of this day. If the study is carried out too late, it is allowed to drink some water. It is better to take food with you and have a snack immediately after blood sampling, rather than violate this condition.

2 days before the appointed day of the study, all foods that are strong allergens should be excluded from the diet, even if you have never had an allergy to them - these are chocolate, nuts, seafood, as well as very fatty foods and smoked meats.

Otherwise, the risk of obtaining false results is significantly increased.

Consider what deviations from the normal values ​​of β-hCG and PAPP-A may indicate.

β-hCG - human chorionic gonadotropin

This hormone is produced by the chorion (“shell” of the fetus), thanks to this hormone, it is possible to determine the presence of pregnancy in the early stages. The level of β-hCG gradually increases in the first months of pregnancy, its maximum level is observed at 11-12 weeks of pregnancy. Then the level of β-hCG gradually decreases, remaining unchanged throughout the second half of pregnancy.

PAPP-A, pregnancy-associated protein-A

This is a protein produced by the placenta in the body of a pregnant woman, is responsible for the immune response during pregnancy, and is also responsible for the normal development and functioning of the placenta.

MoM coefficient

After receiving the results, the doctor evaluates them by calculating the MoM coefficient. This coefficient shows the deviation of the level of indicators in this woman from the average normal value. Normally, the MoM-coefficient is 0.5-2.5 (with multiple pregnancy up to 3.5).

The data of the coefficient and indicators may differ in different laboratories, the level of the hormone and protein can be calculated in other units of measurement. You should not use the data in the article as norms specifically for your study. It is necessary to interpret the results together with your doctor!

Then, using the PRISCA computer program, taking into account all the indicators obtained, the woman’s age, her bad habits (smoking), the presence of diabetes and other diseases, the woman’s weight, the number of fetuses or the presence of IVF, the risk of having a child with genetic abnormalities is calculated. A high risk is a risk of less than 1:380.

Example: If the conclusion indicates a high risk of 1:280, this means that out of 280 pregnant women with the same indicators, one will have a child with a genetic pathology.

Special situations where the indicators may be different.

• IVF - β-hCG values ​​​​will be higher, and PAPP-A - below average.
• When a woman is obese, her hormone levels may increase.
• In multiple pregnancies, β-hCG is higher and the norms for such cases have not yet been precisely established.
• Maternal diabetes can cause hormone levels to rise.

This type of examination is prescribed for women who are diagnosed with 11-13 weeks of pregnancy. The initial stage of the first screening during pregnancy is an ultrasound examination. After that, the pregnant woman is sent for a biochemical blood test.

Such events make it possible to identify genetic defects, pathologies in the structure of the embryo and respond to them in a timely manner.

How to prepare for the first screening?

The procedure under consideration includes two types of examination, each of which needs a certain preparation.

ultrasound

Can be done in two ways:

1. External (abdominal). It is given with a full bladder, therefore, 30-60 minutes before the start of the procedure, the pregnant woman must drink at least half a liter of purified water without gas, or not urinate 3-4 hours before the start of the ultrasound.
2. Vaginal. This type of examination does not require special preparation. Some clinics require patients to come to the appointment with their own diaper, sterile gloves and a condom for the ultrasound transducer. All this can be purchased at almost any pharmacy.

(double test)

It provides for the following preparatory measures, ignoring which can significantly affect the test results:

• 2-3 days before the analysis, a pregnant woman should refrain from fatty, salty foods (meat, seafood), citrus fruits and chocolate. The same goes for multivitamins.
• Blood must be donated on an empty stomach. The last meal should be at least 4 hours before the test.
• Doctors also advise to exclude sexual intercourse a couple of days before the screening.

How does the first screening in pregnant women go and what does it show?

The specified type of examination must begin with. After all, it is ultrasound diagnostics that makes it possible to determine the exact gestational age - and this very important for the second stage of screening: the double test. After all, the indicators of the blood norm, for example, for 11 and 13 weeks will be different.

In addition, if an ultrasound scan detects the fetal fading or the presence of serious anomalies in it, there will be no need for a biochemical blood test.

Thus, at the time of passing the second stage of the first screening, the pregnant woman should have the conclusion of an ultrasound doctor in her hands.

Ultrasonography

The type of examination under consideration favors the identification of such physical defects of the fetus:

• developmental delay.
• The presence of serious pathologies.

Also thanks to ultrasound the gestational age is determined, the number of fetuses in the uterus, the approximate date of birth is set.

In the first third of pregnancy, the following indicators are checked on an ultrasound machine:

1. The distance from the coccyx to the parietal part of the head. This parameter is also called the coccygeal-parietal size (KTR). At the 11th week of pregnancy, the CTE varies within 42-50 mm, at the 12th week - 51-59 mm, at the 13th - 62-73 mm.
2. The size of the nasal bone. At the 11th week, it is not visualized. At 12-13 weeks, its parameters are more than 3 mm.
3. The distance between the tubercles of the parietal region, or biparietal size (BDP). Normally, this indicator should be 17 mm at the 11th week; 20 mm at 12 weeks; 26 mm at the 13th week of pregnancy.
4. Embryo head circumference.
5. The distance from the forehead to the back of the head.
6. The structure of the brain, symmetry and size of its hemispheres, the quality of the closed skull.
7. Heart rate (HR). By means of this parameter, cardiac arrhythmia can be detected. When measuring the heart rate, the sonographer must be very careful: due to the short duration of pregnancy, it is possible to confuse the pulsation of the patient's vessels with the heartbeat of the embryo. Normally, the indicator in question varies between: 153-177 at the 11th week of pregnancy; 150-174 - at the 12th week; 147-171 - on the 13th.
8. Parameters of the heart and its arteries.
9. The structure of the femur, shoulder, tibia.
10. The distance between the inner and outer surface of the skin of the neck, or the thickness of the collar space (TVP). Normally, this indicator will be: at the 11th week of pregnancy 1.6-2.4 mm; at the 12th week - 1.6-2.5 mm; at the 13th week - 1.7-2.7 mm.
11. The structure of the chorion (placenta), its location. Upon detection of exfoliation of the chorion, its volumes are established and whether there is a tendency to progress. A similar phenomenon can provoke spotting and complaints of a pregnant woman about pain.
12. Shape and size of the yolk sac, the quality of supply of the umbilical cord with vessels. The yolk sac normally decreases in size by the 12th week of pregnancy, and at the time of ultrasound diagnosis, it should be a tiny (4-6 mm) cystic neoplasm of a rounded shape.
13. The structure of the uterus, its appendages. Particular attention is paid to the ovaries: in the later stages of pregnancy, it is problematic to examine them.

At the time of the first screening ultrasound the fetus must be positioned correctly so that the specialist can carry out a qualitative inspection and make the necessary measurements.

If the child is not positioned correctly, the patient is asked to roll over from her back to her side, cough, or squat.

Double test (norms and interpretation)

For this type of examination, blood is used from a vein, which is taken on an empty stomach.

Biochemical screening is needed to determine the following parameters:

1.Protein Pregnancy (PAAP) -A )

This protein is produced by the placenta and increases with the course of pregnancy.

Normally, the indicators of this protein will be as follows:

• 11-12 weeks: 0.77-4.76 honey / ml.
• 12-13 weeks: 1.04-6.01 mU / ml.
• 13-14 weeks: 1.48-8.54 mU / ml.

A reduced amount of PAAP-A may be due to the following deviations:

1. There is a threat of miscarriage.
2. The developing embryo has Down syndrome, Edwards syndrome, or another genetic disease.

An increase in the level of PAAP-P in the blood of a future mother often does not have an important diagnostic value.

2. Amounts of human chorionic gonadotropin (hCG)

This hormone is produced in the first weeks of pregnancy, reaching a maximum level at the 12th week of pregnancy, after which the amount of the hormone in question decreases.

By studying the indicators of the amount of hCG in the blood of a pregnant woman, it is possible to determine the presence / absence of chromosomal abnormalities.

In the conclusion sheet, this parameter is written in the column “free β-hCG”.

In the first trimester of pregnancy, the norm of this hormone is as follows:

• 11th week: 17.3-130.2 ng / ml.
• 12th week: 13.3-128.4 ng / ml.
• 13th week: 14.3-114.7 ng / ml.

Elevated levels of hCG may indicate several phenomena:

• A developing fetus has Down syndrome.
• The mother-to-be has diabetes.
• The pregnant woman suffers from severe toxicosis.

A decrease in the level of the hormone in question may occur against the background of the following factors:

• There is a risk of miscarriage.
• Pregnancy formed outside the uterine cavity
• Failure of the placenta to perform its basic functions.
• The fetus has Edwards syndrome.

What pathologies can be detected on the screening of the first trimester?

In the first three months of pregnancy, through examinations, it is possible to identify or suspect the presence of the following ailments:

• Errors in the structure of the neural tube (meningocele).
• Down Syndrome. The prevalence of this disease: 1:700. Timely detection of this pathology made it possible to reduce the birth rate of sick babies (1 per 1100 cases).
• Umbilical hernia (omphalocele). Ultrasound examination shows that the internal organs are in the hernial sac, and not in the abdominal cavity.
• Edwards syndrome (1:7000). It is characterized by a reduced heart rate, omphalocele, insufficient number of blood vessels on the umbilical cord, absence (inability to visualize) the nasal bone. Pregnant women over 35 years of age are at risk.
• triploidy. With this pathology, instead of 46, there are 69 chromosomes in a fertilized egg. Such a phenomenon may occur due to an incorrect structure of the egg, or when two spermatozoa penetrate one egg. Often, with such anomalies, women do not bear a fetus, or give birth to dead children. In those rare cases when it was possible to give birth to a live baby, the period of his life is limited to a few days / weeks.
• Patau disease (1:10000). Ultrasound ascertains retardation in the structure of the brain, tubular bones, increased heart rate, omphalocele. Often, babies that are born with a similar diagnosis live a maximum of a couple of months.
• Smith-Lemli-Opitz syndrome (1:30000). It is the result of genetic disorders, due to which the qualitative assimilation of cholesterol is impossible. The pathology under consideration is capable of provoking many malformations in development, the most serious of which are errors in the functioning of the brain and internal organs.

To confirm some of the above pathologies, it is required additional diagnostic measures, and in most cases they are invasive.

What can affect the results, and can the doctor make a mistake at the first screening?

Screening for the first trimester of pregnancy has certain disadvantages.

On the other hand, it is still necessary to conduct an examination: timely detection of a particular pathology will make it possible to terminate the pregnancy (if the fetus is with severe abnormalities), or take measures to maintain the pregnancy (if there is a threat).

In any case, it will be useful for any expectant mother to know that false positive screening results can occur in the following situations:

1. ECO. With artificial insemination, the parameters of the occipital part of the embryo will be 10-15% higher than normal. A double test will show an increased amount of hCG, and a low level (up to 20%) of PAAP-A.
2. Weight of the expectant mother: severe thinness is a consequence of a decrease in the amount of hormones, and with obesity, the opposite phenomenon is observed.

Many women who are preparing to undergo their first examinations during pregnancy are interested in what are the 1st trimester screening rates.

If you want to know what indicators characterize the fetus at this time, what the result of an ultrasound scan and blood tests can be, and how to properly prepare to donate blood, then read this article.

Screening of the first trimester is a responsible event that should not be neglected.

The results of the tests that you will receive after passing it will allow the doctors to assess the actual condition of your child and draw the right conclusions regarding the further course of the pregnancy.

Women in the first trimester of pregnancy are often surprised to learn that the first screening of their condition and fetal development is carried out using two procedures: ultrasound diagnostics and blood sampling.

Most often, at this time, ultrasound of the fetus is performed abdominally - through the abdominal walls of the mother's abdomen.

A woman who is going to undergo such an ultrasound should prepare for it - drink a few glasses of cool non-carbonated clean water.

The fluid that has entered the bladder will create a certain load on the uterus, and an ultrasound will be performed with more accurate data.

The sonologist conducting the ultrasound evaluates the development of the child, which should correspond to his gestational age, and the biometrics of the fetus, comparing the actual size of the fetus with the normative ones.

After that, the doctor measures various parameters, the analysis of which can give an informative conclusion about the actual state of the fetus, confirm or exclude the presence of pathologies in its development.

The optimal time for the first pregnancy screening is the twelfth to thirteenth week of its development. The result of the study is based on several factors.

Below you can find the average data that are normative for children with this gestational age.

The normative thickness of the collar space, measured at this time, should range from one and a half to two and a half millimeters.

If the VP is thicker, doctors may suspect various fetal chromosomal abnormalities. You can clarify their presence by visiting a number of additional prenatal non-invasive diagnostics.

It is important to pay attention to the fact that TVP is measured only at the first pregnancy screening, since it cannot be determined at subsequent ultrasounds.

In addition, the following fetal indicators are analyzed (at the twelfth to thirteenth week of pregnancy):

1. the size of the nasal bone is at least three millimeters;
2. heart rate - from one hundred and fifty to one hundred and seventy beats per minute;
3. spectrum of blood flow in the venous duct of the fetus;
4. the size of the baby's upper jaw bone;
5. bladder capacity.

The result of an ultrasound, signaling possible deviations upwards from the norm, may indicate the presence of various gene anomalies, in particular, Down syndrome.

Fetal biometry performed at the twelfth to thirteenth gestational week of development must comply with the following standard indicators:

• biparietal size - from fourteen to twenty-six millimeters;
• coccygeal-parietal size - from thirty-two to seventy-four millimeters;
• head circumference - from sixty-two to ninety-eight millimeters;
• abdominal circumference - from fifty-one millimeters to seventy-eight millimeters;
• the length of the thigh bone is from five and a half to twelve and a half millimeters;
• the height of the child is from ninety to one hundred and ten millimeters;
• weight - around seventy grams.

HCG norms during the first screening (blood test)

The best time to take a blood test is the day on which you will have an ultrasound.

In order for the data to be as accurate as possible, you should prepare for blood sampling - do not eat for twelve hours before the procedure, and also follow a mandatory diet.

Eliminate from your diet:

• chocolate and other sweets;
• meat, fish, smoked meats;
• carbonated drinks.

Doctors who take blood from pregnant patients send it to a special laboratory.

In this place, it is tested for two indicators:

1. human chorionic gonadotropin (hCG);
2. RAPP-A.

Ideally, screening for the first trimester of pregnancy should take place on one day. In the early morning, you must donate blood from a vein, then undergo an ultrasound procedure.

Due to this, the result of dual diagnostics will be accurate and will help doctors to reliably determine the condition of the fetus.

Human chorionic gonadotropin is a hormone that is present in the blood of every pregnant woman. Its amount allows you to set the exact gestational age of the fetus.

The norm of human chorionic gonadotropin at the twelfth - thirteenth week of pregnancy is from thirteen and a half to one hundred and fifteen ng / ml.

Elevated levels of hCG may indicate various gene abnormalities in the development of the child.

However, the level of hubbub, which differs upwards from the norm, may also indicate other factors:

• multiple pregnancy;
• acute toxicosis;
• intoxication with various drugs taken by a woman during the first trimester of pregnancy;
• maternal diabetes;
• various tumor neoplasms of unknown origin;
• the presence of Down syndrome in the fetus;
• bubble drift.

In turn, a reduced level of human chorionic gonadotropin may indicate:

• for an ectopic pregnancy;
• for a frozen pregnancy;
• for the presence of a threat of miscarriage;
• for the presence of Edwards syndrome in the fetus.

If the result of the tests causes serious concern to the gynecologist in charge of the pregnancy, then most likely he will prescribe an additional invasive procedure, which consists in a biopsy of the chorionic villi.

This procedure will more likely clarify the condition of the fetus and confirm or exclude the presence of anomalies in its development.

PAPP-A norms during the first screening (blood test)

PAPP-A is a protein compound that is produced by the outer layer of the placenta of a pregnant woman.

The presence of this protein is fixed in the blood throughout pregnancy. The level of PAPP-A increases with each gestational stage of development of a child in the womb.

If the result of blood sampling, checked for the presence and level of PAPP-A, worries the doctor, the doctor will prescribe a number of additional prenatal non-invasive diagnostics.

The result of a blood test for the presence of PAPP-A, carried out at the first pregnancy screening, should range from one to eight and a half mU / ml.

The lag of the level of PAPP-A from the normative indicators corresponding to the current gestational age of the fetus may indicate the presence of Down syndrome or Edwards syndrome.

The result of an analysis that revealed an elevated level of PAPP-A may signal a missed pregnancy or a very real threat of miscarriage.

It should be remembered that the best time to donate blood tested for PAPP-A is the twelfth to thirteenth week of pregnancy.

After the fourteenth gestational week, the result of the PAPP-A analysis may lose its information content.

It is best if you go through all the stages of screening for the first trimester of pregnancy in one medical institution.

Computer programs designed to organize the data obtained during examinations, which are used in various medical institutions, have different settings.

Therefore, to maintain the reliability of the data, you should sign up for blood sampling and ultrasound in the same clinic. These tests can be done both in the city and in a private hospital.

If the result of blood biochemistry, which you receive after taking the tests, alerts the doctor, despite the fact that the first ultrasound will not cause him any complaints, then the doctor will recommend that you undergo an additional examination.

At the first stage, it consists in repeated ultrasound diagnostics.

If the result of this procedure is uninformative and cannot clarify the picture, then most likely you will be referred for an ultrasound with dopplerometry.

Combined screening, carried out at the end of the first trimester of pregnancy at the twelfth to thirteenth week of the gestational age of the fetus, will assess vital signs and draw a conclusion about the health of the child in the womb.

Every woman who cares about the baby's condition must undergo an ultrasound scan and donate blood for PAPP-A and human chorionic gonadotropin.

These procedures are absolutely safe and do not cause any harm to either the condition of the woman or the health of the fetus.