This new fashion word has appeared in medicine relatively recently. What is screening for pregnancy? This is a set of tests to determine any abnormalities of the hormonal background during the gestation of the fetus. Screenings during pregnancy are conducted to identify a group of risks of congenital malformations, for example, Down's Syndrome or Edwards Syndrome.
The results of screening for pregnant women can be found after a blood test taken from a vein, as well as after an ultrasound. All details of the course of pregnancy and the physiological characteristics of the mother are taken into consideration: growth, weight, the presence of bad habits, the use of hormonal drugs, etc.
How many screenings are made for pregnancy?
As a rule, during pregnancy 2 full screenings are carried out. They are divided by time a few weeks. And they have minor differences from each other.
First trimester screening
It is carried out on the 11-13 weeks of pregnancy. This comprehensive examination is designed to determine the risk of congenital malformations in the fetus. The screening includes 2 tests - ultrasound and a study of venous blood for 2 types of homons - b-HCG and RAPP-A.
On ultrasound, you can determine the physique of the baby, its correct formation. The circulatory system of the child, the work of his heart, is investigated, the length of the body is determined relative to the norm. Special measurements are made, for example, the thickness of the cervical fold is measured.
Since the first screening of the fetus is complex, it is too early to draw conclusions on its basis. If there is a suspicion of certain genetic malformations, the woman is sent for an additional examination.
Screening for the first trimester is an optional study. It is sent to women with an increased risk of developing pathologies. These include those who are going to give birth after 35 years, who have sick people with genetic pathologies in their family or who have had miscarriages and the birth of children with genetic abnormalities.
Second Screening
It is performed on the 16-18 weeks gestation period. In this case, the blood is taken to determine the 3 types of hormones - AFP, b-HCG and free estirol. Sometimes a fourth indicator is added: inhibin A.
Estirol is a female steroid sex hormone produced by the placenta. Insufficient level of its development can talk about possible violations of fetal development.
AFP (Alpha-fetoprotein) is a protein found in the serum of maternal blood. It is produced only during pregnancy. If there is an increased or decreased protein content in the blood, this indicates a violation of the fetus. With a sharp increase in AFP, fetal death may occur.
Screening of chromosome pathology of the fetus is possible when determining the level of inhibin A. Lowering the level of this indicator indicates the presence of chromosomal abnormalities, which can lead to the syndrome of Down or Edwards syndrome.
Biochemical screening in pregnancy is designed to identify Down's syndrome and Edwards syndrome, as well as neural tube defects, defects in the anterior abdominal wall, fetal kidney anomalies.
Down syndrome AFP is usually lower,
It should be said that the biochemical test reveals only 90% of the cases of neural tube malformations, and Down's Syndrome and Edwards syndrome determine only in 70%. That is, about 30% of false negative results and 10% of false positives occur. To avoid error, the test should ideally be evaluated in conjunction with the ultrasound of the fetus.