Biochemical blood test screening 1st trimester transcript. What is screening during pregnancy: how and when it is done

Prenatal or 1st trimester screening – what is this procedure? How does it work 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 to identify possible pathologies, disorders and genetic abnormalities intrauterine development child. The deadline for scheduling the procedure is no earlier than 11 weeks. It is mandatory to take it up to 13 weeks and 6 subsequent permissible days during pregnancy:

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

The very first screening is carried out in accordance with the resolution of the Ministry of Health. The gynecologist decides which week it should be done. Usually no later than 13 expected weeks. The prescribed screening for the 1st trimester includes an ultrasound scan, blood testing, 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 delay of the expected menstruation, an ultrasound examination shows the presence of pregnancy, the approximate timing of the fetus, its development and possible diseases or violations. It passes abdominally, that is, the abdominal wall is used for examination, without insertion into the vagina. Preparation required:

diet. Approximately 3 days before the scheduled examination. You should not eat legumes, cabbage, carbonated drinks, baked goods, or fruits before an ultrasound;
full bladder. 3 hours before the ultrasound, you should not urinate;
is carried out strictly on an empty stomach. You should not eat food 4 hours before the diagnosis.

Less commonly, a transvaginal or pelvic ultrasound may be performed. More informative. Diagnosis is carried out by inserting an ultrasound sensor into the vagina. No preparation or special diet is required. Screening indicators during pregnancy in the first weeks:

location of the uterus. Meaning "anteflexio";
contours. Must be defined as smooth;
uterus dimensions: 70mm x 60mm x 40mm. Correspond to length, width, diameter;
walls. The echogenicity is homogeneous;
fertilized egg. Diameter up to 5 mm or more depending on the period;
decidualization of the endometrium. Indicates pregnancy;
the uterine cavity is homogeneous;
ovarian sizes. Width, length and thickness correspond to the following values: 25mm x 30mm x 15mm.

This examination is usually part of a regular medical examination. A gynecologist cannot always determine pregnancy on his own. If the pregnancy test shows a positive result, further diagnosis is carried out on early stages. An ultrasound cannot be done earlier than 1.5-2 weeks after a missed period.

Ultrasound at 12 weeks

Prescribed 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, complete exclusion of sweets, chocolate, seafood, fatty foods, legumes and cabbage;
do not urinate for 2-3 hours before the test. When performing abdominal, external ultrasound.

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

embryo size. Measurements are taken from the head to the tailbone. KTE indicator;
distance from temple to temple. BPR data;
thickness, density of the collar space, TVP;
calculation of heartbeats and their frequency, heart rate.

All future parents dream of finding out the sex of the baby through an ultrasound at 12 weeks. But this cannot be determined with certainty. Errors on the part of doctors are too common. In this case, it is better to perform an ultrasound at 16 weeks of fetal development.

Norm and interpretation of results

Many patients ask which week is the best time to do ultrasound screening. If there is data from a previous ultrasound, exact dates are assigned, which assume 12 weeks of pregnancy. In other cases, the timing is determined by a gynecological examination. The norm and interpretation of the results of the first ultrasound should have the following indicators:

10 weeks. KTR 33 - 41 mm. TVP up to 2.2 mm. The nasal bone is visible. Heart rate is 161-179 beats. BPR 14 mm;
11 weeks. CTE up to 50 mm. TVP – up to 2.4 mm. The nasal bone is visualized. Heart rate – 153 – 177. BPR 17 mm;
12 weeks. CTR up to 59 mm. TVP up to 2.5 mm. The nasal bone is more than 3 mm. Heart rate is 150-174. BPR 20 mm;
13 weeks. CTE no more than 73 mm. TVP up to 2.7 mm. Nasal bone more than 3 mm. Heart rate - 147-171. BPR 26 mm.

In addition to these data, the baby’s head circumference, the structure of the brain regions, and the distance from the bones: frontal and occipital are determined. The forearms, pelvic bones and thighs are visible. Sizes of the heart and ventricles. The doctor takes into account amniotic fluid, thickness of the placenta. It is also possible bad results Ultrasounds that indicate the genetic risk of developing a sick fetus and corresponding syndromes:

Down. The TVP or nuchal fold of skin on the baby’s neck has a width of up to 2.8. It is filled with liquid. In Down syndrome, the fluid is dark in color. The nasal bone is shortened, the distance between the eyes is increased, tachycardia and heart pathologies are observed;
Edwards. Bradycardia or a decrease in heart rate in the fetus appears, the nasal bone is missing, only one artery is observed in the umbilical cord, an abdominal hernia;
Patau. Enlarged bladder, tachycardia, impaired brain formation;
Turner. The fetus has a rapid, unnatural heartbeat and developmental delay corresponding to 8 weeks of pregnancy;
Smith-Lemli-Opitz. Hereditary genetic disease. The reason is a violation of cholesterol metabolism. Characterized by mutations, craniofacial anomalies, neurological abnormalities;
de Lange. A disease for which the genetic risk factor is 25%. The condition is possible mutations in the parents. In the fetus, the false positive rate is 5%;
Triploidy. Lack of division into the corresponding parts of the brain, holoprosencephaly. Decreased heart rate, bradycardia. Omphalocele or malposition of abdominal organs. Enlargement of the renal pelvis and more than two cysts in the cranial area.

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

Biochemical screening

This examination must be done immediately after the ultrasound diagnosis. What is this: biochemical screening? When the timing of pregnancy has been identified, all indicators of fetal development are indicated, a biochemical blood test or genetic screening must be performed. How does the preparation go:

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

It is advisable to study the hormonal composition of the blood on the same day as an ultrasound examination. Then the doctor will be able to objectively evaluate the results and 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 line when taking a regular pregnancy test at home. HCG levels are ambiguous. If it is elevated in the blood, it is possible that future parents should expect twins. Interpretation of β-hCG results 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 have Down syndrome and the mother may have diabetes mellitus or toxicosis. A decrease in the β-hCG norm warns of a possible pathology such as Edwards syndrome, the risk of miscarriage, placental insufficiency or ectopic pregnancy. Until the 12th week, this hormone increases, but within normal limits. After that it goes down.

PAPP-A norm at 12 weeks

A protein, protein-A, which is produced by the placenta during pregnancy. He points to normal course fetal development. If PAPP-A is elevated, a woman may experience miscarriage or miscarriage. A decrease in protein indicates genetic diseases. Indicators PAPP-A standards in blood:

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

Low rates are a genetic risk for pathologies. Diseases such as Down syndrome, Edwards syndrome, de Lange syndrome. This test 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. Typically it ranges from 0.5 to 2.5. If it is exceeded to a value of 3.5, it means there are several embryos. The final type of result can be “positive” for pathology or “negative”. Subsequent examination will take place in the 2nd trimester.

The approximate cost of this procedure depends on the location where it is performed. Prenatal diagnostics will cost 1,600 rubles. The difference between ultrasound and biochemical blood sampling for research should not be more than 5 days. You must have all the information about previous examinations with you.

1st trimester screening: what should diagnostics show?

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

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

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

If the 1st trimester ultrasound screening is generally normal, but the individual risk of having a sick child is high, then the doctor may recommend waiting for the second screening or conducting invasive diagnostics, the result of which can be used to say for sure whether the child is genetically healthy.

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

After 16 weeks, amniocentesis is performed. Amniotic fluid is taken for analysis. This analysis is considered very informative and safer than chorionic villus sampling and cordocentesis. Women usually agree to the first one in order to avoid prolonged gestation of a non-viable fetus. After all, after 12-13 weeks you need to wait until the doctors can call artificial birth. And this is approximately 18 weeks.

But if you do not meet the 1st trimester ultrasound screening standards, and do not want to wait for the second screening, much less invasive diagnostics, there is the opportunity to do a non-invasive test. It is not yet widespread in Russia. And very expensive. The analysis costs about 30,000 rubles. But its reliability is approximately the same as amniocentesis. There is no risk spontaneous interruption pregnancy.

First trimester screening involves examining the levels of two hormones in the blood of the expectant mother - hCG and PAPP-A. A high hCG may indicate a high risk of Down syndrome in a child, and a low one may indicate a high risk of Edwards syndrome. At the same time, PAPP-A also turns out to be low. But the final interpretation of the 1st trimester screening results is performed only together with an ultrasound scan.

The results of blood tests can be affected by a situation where a woman has a clear threat of miscarriage if she is taking progesterone drugs. But many pregnancies are at risk. In addition, it plays a role whether a woman is carrying one fetus or several, whether she is overweight or underweight, and whether the conception was natural or in vitro fertilization. Therefore, it is completely wrong to try to interpret and worry about blood tests separately.

When is it better to do screening in the first trimester? The gynecologist can and should calculate it directly. This is why it is important to register for pregnancy before 12 weeks. It is advisable to visit a doctor for the first time no later than 8-9 weeks, since there is a shortage of coupons for free screening in many Russian regions. You may need to wait a little longer to receive your voucher. You will have extra time just for this waiting.

But the timing of 1st trimester screening has been determined. All that remains is to donate blood and do an ultrasound on the specified day. Many women believe that to make the result more reliable, some measures need to be taken. Should preparation be made for the first screening during pregnancy and what kind? There is no need for any preparation as such. Some experts recommend following a diet a few days before the examination, but there is no great need for this. No need to the expectant mother limit yourself in nutrition. And one more important question - how is screening of the first trimester done on an empty stomach or not, what is better? In general, it is advisable to take all blood tests on an empty stomach. Including this one. But sometimes it happens that the analysis is scheduled for the second half of the day. Then, of course, you should not go hungry since the evening of the previous day.

An ultrasound is performed. Moreover, sometimes the doctor requires not only abdominal access, but also vaginal access. The indicators that the doctor is especially interested in are the thickness of the collar space, visualization and size of the nasal bone, and the speed of venous blood flow. In addition, the doctor examines all organs and systems of the fetus, the size of the limbs and head. Measures a woman's cervix in order to early diagnose isthmic-cervical insufficiency, if present.

The results of the 1st trimester biochemical screening are usually ready within a few days. And all this time the expectant mother is in suspense. Especially if you have read or are personally familiar with bad stories related to this examination. Typically, a woman visits a doctor once every 2-3 weeks, and if a high-risk screening result comes earlier than she should attend antenatal clinic, the doctor or midwife calls her and invites her to come over. If the first trimester screening is good, you don’t have to worry and don’t have to take anything additional or visit a geneticist. It should be noted that young women have a much lower risk of chromosomal abnormalities.

Screening for the 2nd trimester consists of taking three blood parameters. But it is usually prescribed only to those women who either did not pass the first screening or whose results were unsatisfactory.

And in conclusion, it is necessary to say how necessary the first screening is in general. Is it possible to do without it? Of course, yes, it all depends only on the desire of the woman. An ultrasound scan at 12 weeks can reveal severe malformations. Well, high or low risk does not guarantee the birth of a sick or healthy child.

However, classical screening is recommended for women over 35 years of age and those who already have children with genetic abnormalities, or cases of bearing children with chromosomal abnormalities, if there are abnormalities in the genetic code.

Prenatal screenings cause a lot of conflicting opinions and reviews. Some are convinced of their necessity, others are confident of their complete inexpediency. What are these tests, and should all pregnant women really undergo them? We decided to look into this issue.

Prenatal screening is a complex of studies, the main goal of which is to identify a risk group of pregnant women with possible malformations of the child (such as: Edwards syndrome, neural tube defects (anencephaly), Cornelia de Lange syndrome, Smith Lemli Opitz syndrome, triploidy, Patau syndrome ).

Despite the fact that screenings include two fairly proven diagnostic methods - and ultrasound, their reliability and safety still cause a lot of controversy.

Cons No. 1: Ultrasound is harmful to the baby

There is a fairly widespread belief that ultrasound has a negative effect on nervous system the child, irritates him - during the examination, children often try to hide from the device, covering their heads with their hands. Therefore, children whose mothers regularly had ultrasound scans during pregnancy are more restless compared to babies whose mothers refused ultrasound diagnostics. Is it really?

According to doctors, ultrasound cannot cause any harm to the baby - modern equipment is absolutely safe. Therefore, official medicine insists that absolutely all pregnant women undergo an ultrasound. After all, timely diagnosis allows, firstly, to see full picture the course of pregnancy, and secondly, if necessary, correct certain problems.

An ultrasound examination is performed at least three times during pregnancy (on, on, and on), but if necessary, the doctor may recommend having it more often.

The data obtained from the ultrasound of the first prenatal screening (on) are considered especially important. At this time during the study:

the number of embryos in the uterus and their viability are determined;
more accurate is set;
gross malformations are excluded;
the thickness of the collar space is determined - TVP (i.e. the amount of subcutaneous fluid on the back surface of the child’s neck is measured - normally TVP should not exceed 2.7 mm);
The presence or absence of the nasal bone is examined.

For example, in children with Down syndrome, the fluid content is much higher than normal, and the nasal bone is often not visualized.

Screening in the first trimester of pregnancy is a comprehensive examination, including ultrasound examination of the fetus and a biochemical blood test from a vein of the pregnant woman. Analyzed together, taking into account the patient’s age and medical history, the results of these procedures make it possible to identify genetic pathologies of the fetus at an early stage of development.

The first screening during pregnancy is carried out strictly from 11 to 13 obstetric weeks pregnancy. The examination results help to begin treatment in a timely manner if genetic defects of intrauterine development are detected or to make a decision to terminate the pregnancy.

Ultrasonography

Ultrasound allows you to accurately determine the gestational age, so it is prescribed before taking a biochemical blood test.

The procedure includes examination of the chorion, from which the placenta will subsequently form, assessment of the tone of the uterus and the condition of the ovaries. During the study, the symmetry of the hemispheres and the degree of development of the fetal brain, the presence and symmetry of the arms and legs, the correct position of the heart and stomach are determined, the length of the femurs, humerus, forearm and shin bones is measured.

When calculating the risks of developing genetic pathology of the fetus, the following are taken into account, depending on the week of pregnancy:

The thickness of the nuchal space (TN), that is, the distance from the inner surface of the skin of the neck to the outer surface of the soft tissues covering the cervical spine. Normally, it is 0.8 - 2.8 mm; the more the value of the collar zone exceeds the norm, the higher the risk of a chromosomal abnormality in the fetus. More accurately, this risk can be calculated in the aggregate of all screening data in the first trimester of pregnancy.
Presence of a nasal bone; for a period of 12-13 weeks of pregnancy, the length of the nasal bone is normally at least 3 mm.
Correspondence of anthropological parameters of the fetus to the gestational age:

biparietal head diameter (BPD), the distance from the forehead to the back of the head, at 13 weeks - an average of 26 mm;
coccyx-parietal size (KTR) - length from the coccyx to the crown, normally from 45 to 84 mm;
heart rate (HR); 147-171 beats per minute at 13 weeks.

NOTE. It is impossible to diagnose Down syndrome and other genetic pathologies based only on ultrasound data. It is necessary to evaluate the results obtained in conjunction with indicators of chromosomal abnormalities obtained from a blood test.

Blood biochemistry

Blood for biochemical analysis is taken from a vein, early in the morning, on an empty stomach. It checks the level of two important indicators of genetic pathologies that are part of human chorionic gonadotropin () - a hormone present only in the body of a pregnant woman:

free beta (β) hCG. Responsible for the support and development of pregnancy, secreted by the cells of the embryo membrane (chorion).
If the indicator less than normal, we can talk about the threat of miscarriage, placental insufficiency, ectopic pregnancy, the likelihood of Edwards syndrome in the fetus. Exceeding the level of free β-hCG can be not only due to chromosomal mutations, including Down syndrome, but also due to multiple pregnancy or maternal illness with diabetes mellitus.
PAPP-A protein (plasma protein). Synthesized by plasma, ensures the development and functioning of the placenta, and is responsible for immunity.
If the indicator exceeds the normal value, it may indicate possible genetic pathologies of the fetus, as well as increased tone uterus, regression of pregnancy, threat of miscarriage.

ON A NOTE! The hCG level in a woman who became pregnant as a result of in vitro fertilization (IVF) is higher than in a woman who became pregnant during natural fertilization, and PAPP is lower, by 10-15%. If a pregnant woman is overweight, the levels of all hormones are increased; if the body weight is low, the levels may be decreased. The psychological state of the pregnant woman also affects the results.

To assess the risk of developing abnormalities based on the results of an analysis for beta-hCG or PAPP-A, a coefficient (MoM) is used, calculated as the ratio of the level of hCG or PAPP-A according to a blood test to the average norm at a specific stage of pregnancy. A variant of the norm is considered to be values from 0.5 to 2.5 MΩ (up to 3.5 in case of multiple pregnancy).

The risk assessment is expressed as a fraction for each syndrome. For example, a 1:250 entry for Down syndrome means that in 250 pregnancies with similar screening results, 1 child will be born with Down syndrome.

IMPORTANT! In addition to the level of markers of chromosomal disorders, a biochemical blood test may reveal threats of miscarriage that appear only in the third trimester, for example, gestosis. This makes it possible to carry out timely prevention and avoid serious harm to the health of the mother and child.

Chromosomal pathologies are associated primarily with a lack or excess of chromosomes in the set, and most of them are incompatible with life: children born with such genetic defects most often die in the first months of life (Patau syndrome, Edwards syndrome) or have mental retardation. retardation (Cornelia de Lange syndrome, Smith-Opitz syndrome).

Bad results

High risks of developing a genetic pathology only indicate a greater likelihood of developing an anomaly than the population average. The examination forms a risk group of pregnant women who require increased attention from doctors and additional examinations.

Screening results can be affected by stress, nervous tension, alcohol and coffee consumption, medicines, including hormonal drugs, and smoking.

Having received high indicators of the possibility of genetic diseases, the main thing is not to panic.

It is worth consulting with a geneticist and an obstetrician-gynecologist leading the pregnancy.

Then redo the screening in a center specializing in obstetrics and gynecology, within up to 14 weeks.

Additional examinations should be carried out before a final decision is made to terminate the pregnancy. At 11-13 weeks, this is a chorionic villus biopsy, the chromosome set of which corresponds to the chromosome set of the fetus, so the data will be absolutely accurate. The collection of biomaterial for research is done through a small puncture, under anesthesia.

Geneticists often advise re-screening at 16-18 weeks of pregnancy (second trimester of pregnancy). If indicators of a high risk of having a child with genetic abnormalities persist, samples are taken for analysis to clarify the diagnosis.

amniotic fluid (amniocentesis);
or umbilical cord blood (cordocentesis).

Both of these procedures pose a threat to further pregnancy. Therefore, before prescribing them, it is important to decide what to do if the presence of fetal pathology is confirmed. If parents consciously decide to continue the pregnancy, there is no point in exposing the child to unnecessary risk, and it is better to refuse these diagnostic methods.

NOTE. If the gestational age is incorrectly determined, biochemical screening may be inaccurate. To calculate the obstetric gestational age, you need to indicate the date of the start of the last menstruation. The gestational period, that is, from conception, is determined by ultrasound and may differ from the obstetric period by 1-1.5 weeks.

A woman may be at risk due to age or other indicators, but will be able to safely carry her pregnancy to term, knowing that screening has not shown the likelihood of chromosomal abnormalities in her unborn child. Risk factors for possible chromosomal diseases in the unborn child, in the presence of which screening in the first trimester is mandatory:

marriage between close relatives;
unsuccessful previous pregnancies ( premature birth, frozen pregnancy, stillbirth); a viral or bacterial disease suffered during pregnancy;
presence of relatives suffering from genetic pathologies;
taking medications that should not be used during pregnancy;
age over 35 years.

Details about screening in the 1st trimester of pregnancy are in the video.

Screening in the first trimester of pregnancy is a set of simple and safe examinations for the health of the mother and fetus during the period from the 11th to the 13th week of pregnancy, which allows you to assess the degree of health of the unborn child. For most pregnant women, screening will confirm that they are healthy. And it will identify that small risk group of women who may have children with chromosomal abnormalities. So that, after additional examinations, future parents can make an informed decision to terminate the pregnancy or begin preparing for the birth of a special child with an incurable disease who will require great attention and long-term care.

During pregnancy, a woman is carefully monitored; she regularly undergoes various examinations that help monitor the development of the fetus and the course of pregnancy.

The first trimester is one of the first examinations that a woman undergoes after registration. The essence of screening is to identify the likelihood of developing fetal pathologies. The results of this examination largely influence the woman’s further observation.

When and in what cases is screening prescribed during pregnancy?

First trimester screening is a set of diagnostic procedures that make it possible to identify certain pathologies of fetal development. It is carried out for all pregnant women, without exception, at 10-14 weeks of pregnancy. The optimal time for screening is 12 weeks, since it is during this period that hormone levels are maximum.

The advantages of screening are its simplicity and accessibility. Essentially it includes 2 simple procedures, which are held on the same day: and. Based on both examination methods, the doctor makes a conclusion about the child’s possible diseases.

It is worth remembering that despite the high information content of screening, it only shows possible diseases and not always existing ones. So, for example, with the help of screening you can determine how high the risk of developing Down syndrome is, but whether this syndrome exists can be found out at a later stage. later.

1st trimester screening, which takes only 1-2 days to decipher, helps to identify early and early various diseases and fetal pathologies.

Screening is carried out for everyone, but women should pay special attention to the procedure and preparation in the following cases:

Age over 35 years. If a woman gives birth for the first time after 35 years, she is carefully examined for various genetic abnormalities. With age, the risk of genetic diseases increases.
A history of problems with pregnancy. If a woman has already had miscarriages, missed abortions, or premature births before her current pregnancy, special attention is paid to screening in the first trimester.
Women who have taken drugs prohibited during pregnancy. A woman does not always find out about pregnancy right away. In the very early stages, she may unknowingly take drugs that could harm the fetus. Screening helps identify these harms.
Presence of hereditary diseases. If the woman herself or the father of the child has any hereditary diseases, the development of the fetus is monitored especially closely. The presence of diseases in the parents' immediate relatives is also taken into account.

Preparation and procedure

The procedures are carried out on an empty stomach. First, it is usually done with a full bladder. Before the examination, it is recommended to drink 2 glasses of still water. After the procedure itself, you can go to the toilet and then go to donate blood.

If the ultrasound procedure is performed transvaginally, then filling the bladder is not required. Screening is prescribed to a woman by a doctor. The timing of screening for the 1st trimester is strictly limited: from the 10th week to the 6th day of the 13th week. It is best to carry out screening at 12 weeks, at which time the likelihood of error is minimal. The doctor calculates the gestational age and screening date.

It is carried out on an empty stomach. It is advisable to maintain an interval of 4-6 hours after the last meal. It is recommended to go on a diet for some time before screening: exclude everything fatty, creamy, chocolate, fried. By following these simple rules, the accuracy of the results increases.

In the first trimester, a woman may suffer from toxicosis, nausea, and her taste preferences change. It is not recommended to eat anything before donating blood, even to reduce nausea, as the blood will quickly clot and be unsuitable for examination.To avoid the urge to urinate before an ultrasound, you need to go to the toilet 2 hours before the examination, and then drink a couple of glasses of water. It must be clean still water, but not tea, coffee, juice.The ultrasound screening procedure itself is no different from any other, but the equipment is more powerful, and the doctor has the specialization of a sonologist.

Ultrasound can be performed either transvaginally or transabdominally.

In any case, there will be no pain. A woman walks into a doctor's office, bares her belly or takes off all her clothing to the waist and lies down on the couch. The doctor lubricates the surface of the abdomen with gel and runs a sensor over it.

With transvaginal ultrasound, the sensor has an elongated shape. The doctor puts a special disposable nozzle on it and lubricates it with gel. The sensor is inserted shallowly into the vagina, so there should not be any unpleasant sensations. If bloody discharge appears, the doctor will stop the procedure. It is normal to have a small amount of discharge on the day of the ultrasound or the next day.

During the procedure, the size of the embryo and the size of the heart and brain are assessed. Sometimes the position of the fetus does not allow us to evaluate all its parameters. In this case, the expectant mother is recommended to stand up, walk around, and cough so that the embryo changes its position.

It is advisable to carry out screening no earlier than 11 complete obstetric weeks, so that the size of the embryo allows its organs to be clearly examined.

During the ultrasound procedure, the following parameters are assessed:

Coccyx-parietal size. The size of the embryo from the coccyx to the crown is the most important indicator of its normal development. At the 11th week of pregnancy, this size can reach 42-58 mm, depending on the period. At the end of the 12th week of pregnancy, the CTE already reaches 60-70 mm.
Heart rate. The fetal heart rate may increase, but more often the heart rate decreases as the fetus grows. So, in the 10th week the norm is 160-179 beats per minute, and in the 12th week – 150-174 beats per minute.
. The thickness of the collar zone at the 13th week should be no more than 3. A thickened collar zone may indicate the risk of the child developing Down syndrome and other serious congenital diseases, which can only be reliably identified in late pregnancy.
Biparietal size. This is the distance between the parietal bones. At the 13th week of pregnancy it should not exceed 26 mm. A slight deviation in the normal range of this indicator does not always indicate pathology; more often it is a developmental feature or an incorrectly established period. The increased size of the fetal head indicates either that it is large (if the other sizes are also larger than normal), or that it may develop hydrocephalus.
Nasal bone size. The size of the nasal bone can only be assessed from the 12th week of pregnancy. Therefore, the bone is visible, but its size has no diagnostic value. At week 12, the normal size of the nasal bone is more than 3 mm.
Brain. Normally, the cerebral hemispheres of the embryo develop symmetrically. Its structures are assessed.

Explanation: normal blood test

A blood test during pregnancy is an important indicator of the health status of the pregnant woman and the fetus.

When screening in the first trimester, it primarily shows the level of hormones necessary for the normal development of the fetus. is carried out before and clarifies the duration of pregnancy, whether it coincides with the obstetric one. This is important, since blood counts depend on the period.

Since the test is performed on an empty stomach, it is recommended to take some food with you so that you do not feel sick after the blood is drawn.

It is advisable to exclude all foods that may be strong allergens 2-3 days before donating blood. This should be done even if the woman has never had an allergic reaction. Seafood (especially shrimp and mussels), chocolate, citrus fruits, and honey are excluded from a pregnant woman’s diet.

The main blood parameters that are taken into account during screening in the first trimester are hCG and PAPP-A.

The hormone is called pregnancy hormone or human chorionic gonadotropin. The level of this hormone helps determine pregnancy even before the delay. At 12 weeks of pregnancy hCG level reaches its maximum and then gradually decreases. The boundaries of this hormone are very wide and often depend on the individual characteristics of the mother’s body and the fetus itself. For example, at the 12th week of pregnancy the hCG level ranges from 13 to 128 units. Both indicators will be considered the norm.

Blood levels increase not only with Down syndrome, but also with severe toxicosis and multiple pregnancies, which are determined in advance by ultrasound. A low hCG level may indicate ectopic pregnancy which an ultrasound will show, as well as a high risk of miscarriage. In this case, the woman can be kept for safekeeping.

Useful video - First screening during pregnancy:

PAPP-A is the one that is produced. He is responsible for its normal development and functioning. A deviation from the normal range of this indicator may indicate the presence of chromosomal diseases in the fetus. At week 12, the level of this protein normally reaches 1-6 mU/ml. A reduced level of PAPP-A is considered potentially dangerous due to the high risk of miscarriage.

Possible fetal pathologies

First trimester screening helps identify a large number of fetal pathologies. Not all pathologies require termination of pregnancy; some are corrected and monitored.

The doctor should also warn that the first screening indicates possible pathologies or a high risk of their occurrence, but as a result of the following ultrasound they may be absent:

Down syndrome. Children with Down syndrome have an extra chromosome. On ultrasound during the first screening, the nasal bone is not visualized in the fetus, and the nuchal space is thickened. The thicker the nuchal space, the greater the likelihood of having a child with developmental anomalies. About a third of all pregnancies where the baby has Down syndrome end spontaneous miscarriage or fetal death. Children with this syndrome have serious developmental delays, character traits faces: flat face, flat bridge of the nose, weakly defined brow ridges.
Edwards syndrome. If Down syndrome is known to everyone, then many women have not heard of Edwards syndrome. This is a genetic disease in which one of the chromosomes is duplicated. The reasons for the development of this disease are unknown. A child with this disease can be born to completely healthy parents. In children with Edwards syndrome little weight at birth, underdeveloped jaw, cleft palate or cleft lip, developmental delay. The prognosis is unfavorable; children with this syndrome do not often survive to adulthood.
Pathology of neural tube development. Neural tube developmental defects are quite common among other developmental anomalies. To prevent the development of these defects, mothers are advised to start drinking folic acid while preparing for pregnancy. Children with these defects have various developmental anomalies: from cleft lip to brain cysts.

As a result, the MoM coefficient is indicated, indicating the level of deviation in fetal development. Next, using a special program, taking into account all the data and the woman’s medical history, the ratio is calculated. For example, if 1:300 is indicated, this means that one in 300 women with the same data gives birth to a child with genetic disorders.