What is it?
Of all the prospective mothers that have been examined, a group of women is identified, whose results differ significantly from the norm. This suggests that in their fetus the probability of having any pathologies or defects is higher than that of the others. Prenatal screening is a complex of studies aimed at detecting developmental abnormalities or gross fetal malformations. The complex includes:
♦ biochemical screening - a blood test that allows you to determine the presence of specific substances ("markers") in the blood that change in certain pathologies, such as Down's syndrome, Edwards syndrome, and neural tube defects. Biochemical screening alone is only a confirmation of the probability, but not a diagnosis Therefore, with him additional research is being done;
♦ Ultrasound screening (ultrasound) - is performed in each trimester of pregnancy and allows to identify the majority of anatomical defects and abnormalities of the child's development. Prenatal screening consists of several stages, each of which is important, as it provides information about the development of the child and possible problems.
Risk factors for the development of pathology in the unborn child:
♦ the woman's age is more than 35 years:
♦ having at least two spontaneous abortions in the early stages of pregnancy;
♦ use before the conception or in the early stages of pregnancy of a number of pharmacological preparations;
♦ borne by the future mother bacterial, viral infections;
♦ the presence in the family of a child with genetically confirmed Down's syndrome, other chromosomal diseases, congenital malformations;
♦ family carriage of chromosomal abnormalities;
♦ hereditary diseases in the immediate family;
♦ radiation exposure or other harmful effects on one of the spouses before conception.
What investigates biochemical screening?
• Free subunit of human chorionic hormone (hCG)
• RARP A is a pregnancy-associated plasma protein A.
HGH hormone produces cells of the embryo shell (chorion). It is thanks to the analysis on hCG that pregnancy can be determined already on the 2nd-3rd day after fertilization. The level of this hormone increases in 1 trimester and reaches its maximum by 10-12 weeks. Further, it gradually decreases and remains constant during the second half of pregnancy. The hCG hormone consists of two units (alpha and beta). One of them is a unique beta, which is used in diagnostics.
If the level of hCG is elevated, it can talk about:
• Multiple fetuses (the norm of hCG increases in proportion to the number of fruits);
• Down's syndrome and some other pathologies;
♦ Toxicosis;
♦ diabetes in a future mother;
♦ incorrectly established term of pregnancy.
If the level of hCG is lowered, it can talk about:
♦ presence of an ectopic pregnancy;
♦ undeveloped pregnancy or the threat of spontaneous abortion;
♦ delayed development of the future baby;
♦ placental insufficiency;
♦ fetal death (in the II-III trimester of pregnancy).
It is calculated by the following formula:
MoM - the value of the indicator in the serum divided by the median value of the indicator for this period of pregnancy. The norm is the value of the indicator close to unity.
There are a number of factors that can influence the value of the obtained indicators:
♦ the weight of the pregnant woman;
♦ Smoking;
♦ taking medications;
• history of diabetes mellitus in a future mother;
• pregnancy as a result of IVF.
Therefore, when calculating risks, doctors use the corrected MoM value. Taking into account all the features and factors. The level of MoM ranges from 0.5 to 2.5. And in the case of multiple pregnancies, up to 3.5 MoM. Depending on the results obtained, it will be clear whether the future mother is at risk for chromosomal pathologies or not. If so, the doctor will advise further research. It is not necessary to worry beforehand if you have been given screening for the second trimester - it is recommended that all pregnant women be screened, regardless of the results of the first stage of the examination. God saves man, who save himself!
II Trimester Surveys
"Triple test"
It is carried out from the 16th to the 20th week of pregnancy (the optimal time from the 16th to the 18th week).
Combined screening
• Ultrasound examination (using data obtained in the first trimester);
• Biochemical screening;
• blood test for AFP;
Free estriol;
• chorionic gonadotropin (hCG). The second screening also aims to identify the risk of having a child with Down's syndrome, Edwards, a neural tube defect and other anomalies. During the second screening, the study of the hormone of the placenta and the fetal liver of the fetus, which also carry the necessary information about the development of the child. What are the hormones of the "triple test" and what is indicated by the increase or decrease in their level in the blood? About the hormone HCG has already been mentioned above, but the other two require explanations.Alfa-fetolrothein (AFP) is a protein present in the blood of the baby on early stages of embryonic development.Created in the liver and gastrointestinal tract of the fetus.The action of alpha-fetaprotein is aimed at protecting the fetus from the maternal immune system.
An increase in the level of AFP indicates the probability of existence:
♦ malformation of the neural tube of the fetus (anencephaly, spina bifida);
♦ Meckel syndrome (a sign - an occipital craniocerebral hernia;
♦ esophagus atresia (pathology of fetal development, when the esophagus in the fetus blindly ends, not reaching the stomach (the child can not take food through the mouth) 1 ";
♦ umbilical hernia;
♦ non-affection of the anterior abdominal wall of the fetus;
♦ Fetal liver necrosis due to viral infection.
Lowering the level of AFP suggests:
♦ Down's syndrome - trisomy 21 (term after 10 weeks of pregnancy);
♦ Edwards syndrome - trisomy 18;
♦ incorrectly defined pregnancy period (greater than necessary for research);
♦ death of the fetus.
- Standards of AFP in serum
Free estriol - this hormone produces first the placenta, and later the liver of the fetus. In the normal course of pregnancy, the level of this hormone is constantly growing.
An increase in the level of estriol can talk about:
♦ Multiple pregnancy;
♦ a large fruit;
♦ liver disease, kidney disease in a future mother.
A decrease in the level of estriol may indicate:
♦ fetoplacental insufficiency;
♦ Down's syndrome;
♦ Anencephaly of the fetus;
♦ the threat of premature delivery;
♦ Adrenal hypoplasia of the fetus;
♦ intrauterine infection. Norms of estriol in the serum.
Ultrasound III Trimester Screening
It is carried out from the 30th to the 34th week of pregnancy (the optimal time is from the 32nd to the 33rd week). The ultrasound examines the condition and location of the placenta, determines the amount of amniotic fluid and the location of the fetus in the uterus. According to the indications, the doctor can prescribe additional studies - dopplerometry and cardiotocography. Doppler - this research is done starting from the 24th week of pregnancy, but most often doctors prescribe it after the 30th week.
Indications for carrying out:
♦ fetoplacental insufficiency;
♦ insufficient increase in the height of the standing of the uterine fundus;
♦ Circumference of the umbilical cord;
♦ gestosis, etc.
Doppler is an ultrasound method that provides information on the fetal blood supply. The speed of blood flow in the vessels of the uterus, the umbilical cord, the middle cerebral artery and the aorta of the fetus is investigated and compared with the rates for this period. According to the results, conclusions are drawn about whether the fetus blood supply is normal, whether there is a lack of oxygen and nutrients. If necessary, drugs are prescribed to improve the blood supply of the placenta. Cardiotocography (CTG) is a method of recording the fetal heart rate and its changes in response to uterine contractions. It is recommended to spend from the 32nd week of pregnancy. This method has no contraindications. CTG is carried out with the help of an ultrasonic sensor, which is fixed on the abdomen of a pregnant woman (usually used external, the so-called indirect CTG). The duration of CTG (from 40 to 60 minutes) depends on the phases of activity and rest of the fetus. CTG can be used to monitor the condition of the baby and during pregnancy, and during the birth itself.
Indications for CTG:
♦ diabetes in a future mother;
♦ pregnancy with a negative Rh factor;
♦ detection of antiphospholipid antibodies during pregnancy;
♦ delay in fetal growth.
The doctor directs to screening and (if necessary) recommends a further examination, but he must not influence the decision of the woman. Many future mothers initially refuse screening studies, arguing that they will give birth in any case, regardless of the results of the study. If you enter into their number and do not want to do screening, then this is your right, and no one can force you. The role of the doctor is to explain why prenatal screenings are carried out, what diagnoses can be made as a result of ongoing research, and in case of invasive diagnostic methods (chorionic biopsy, amniocentesis, cordocentesis), tell about possible risks. After all, the danger of abortion after such examinations is about 2%. The doctor must also warn you about this. Unfortunately, doctors do not always have time to explain in detail the results of screening. We hope that in this article we have been able to clarify some aspects of this important study.