Screening includes safe and simple research methods used for mass screening.
The first screening for pregnancy is aimed at identifying various pathologies in the fetus. It is conducted at 10-14 weeks of pregnancy and includes ultrasound (ultrasound) and a blood test (biochemical screening). Many doctors recommend screening all pregnant women without exception.
Biochemical screening for the first trimester of pregnancy
Biochemical screening is the determination in blood of markers that change in pathologies. For pregnant women, biochemical screening is particularly important, since it is aimed at detecting chromosomal abnormalities in the fetus (such as Down syndrome, Edwards syndrome), and also in detecting malformations of the brain and spinal cord. It represents a blood test for hCG (human chorionic gonadotropin) and on RAPP-A (pregnancy-associated protein-A plasma). At the same time, not only absolute indicators are considered, but also their deviation from the average value established for a given period. If RAPP-A is reduced, this may indicate fetal malformations, as well as Down syndrome or Edwards syndromes. Elevated hCG may indicate a chromosomal disorder or a multiple pregnancy. If the indices of HCG are lower than normal, this may indicate a placental pathology, a threat of miscarriage, the presence of an ectopic or undeveloped pregnancy. However, carrying out only biochemical screening does not make it possible to establish a diagnosis. His results speak only of the risk of developing pathologies and give the doctor an excuse to assign additional studies.
Ultrasound is an important part of 1 screening for pregnancy
For ultrasound examination, determine:
- correctness of the internal organs of the child;
- correct position of the handles and legs;
- Correspondence of the sizes of a body to terms of pregnancy;
- structure and location of the placenta.
And:
- measure blood flow and heart function;
- Measure the collar zone (the neck area between the soft tissues and the skin). The measurement is very important, since liquid can accumulate in this zone, and exceeding the values above the norm (the norm is up to 3 mm) indicates developmental deviations;
- scan and measure the nasal bone. At the time of 11 weeks, it is seen in 98% of children and can not be seen in 70% of children with Down syndrome.
When screening for the first trimester of pregnancy, the probability of identifying Down syndrome and Edwards syndrome is very high and is 60%, and together with the results of ultrasound increases to 85%.
It is important to note that the results of the first screening during pregnancy can be influenced by the following factors:
- Multiple pregnancy (the indices are increased, and biochemical screening does not make any sense);
- weight of a woman (with a large weight, the indicators are usually increased);
- bad habits;
- maternal diseases (for example, a cold at the time of testing or chronic diseases);
- taking medicines;
- improperly set deadlines (rates depend on the period of pregnancy).
These factors need to be considered when considering the results of the first screening of pregnant women. With a slight deviation from the norm, doctors recommend screening for the second trimester. And with a high risk of pathologies, as a rule, repeated ultrasound, additional tests (chorionic villus sampling or amniotic fluid research) are prescribed. It is not superfluous to consult with a geneticist.