One of the most exciting and disturbing activities for pregnant women is prenatal screening. And especially frightening expectant mothers are screening for the second trimester of pregnancy. For what it is needed and whether it is worth it to be afraid - we will analyze in our article.
Who is at risk?
On the recommendation of the World Health Organization prenatal screening is conducted in Russia by all pregnant women. Mandatory research is conducted for women who have the following risk factors:
- age over 35 years;
- presence in the family of a child with chromosomal pathologies;
- marriage between close relatives;
- drugs in the first trimester contraindicated in pregnancy;
- prolonged threat of termination of pregnancy;
- two or more miscarriages;
- irradiation of one of the spouses before conception.
Screening for pregnancy - timing and analysis
Usually prenatal screening for pregnancy is carried out twice: at 10-13 and 16-19 weeks. Its goal is to identify possible severe chromosomal pathologies:
- trisomy of the 21st chromosome (Down syndrome);
- trisomy of the 18th chromosome (Edwards disease);
- defect of the neural tube of the fetus (spinal cord non-proliferation).
Screening consists of the following stages: ultrasound, blood test, interpretation of the data. The last stage is very important: on how well the doctor assesses the fetus's condition, not only the baby's future depends, but also the psychological state of the pregnant woman.
The second screening for pregnancy is, first of all, the so-called triple test, a biochemical blood test, which determines the presence of three indicators:
- alpha-fetoprotein (AFP);
- total hCG;
- free estriol (E3).
Depending on the level of these indicators in the blood of a future mother, they talk about the risk of developing genetic pathologies.
| Violation | AFP | E3 | HCG |
|---|---|---|---|
| Down syndrome (trisomy 21) | Low | Low | Tall |
| Edwards disease (trisomy 18) | Low | Low | Low |
| Nerve tube defects | Tall | Normal | Normal |
The second screening during pregnancy also involves an ultrasound exam Specialist will carefully examine the fetus, its limbs, internal organs, assess the condition of the placenta and amniotic fluid. The timing of the second screening for pregnancy for ultrasound and biochemical blood test do not match: ultrasound is most informative between 20 and 24 weeks, and the optimal time for a triple test is 16-19 weeks.
Let's figure out the figures
Unfortunately, not all doctors decipher the results of the triple test to future mothers. In the second screening for pregnancy, the following indicators are the norm:
- AFP at 15-19 weeks of gestation - 15-95 U / ml and at 20-24 weeks - 27-125 U / ml.
- HCG at the 15-25th week of pregnancy - 10000-35000 mU / ml.
- Free estriol at 17-18 weeks - 6,6-25,0 nmol / l, at 19-20 week - 7,5-28,0 nmol / l and at 21-22 week - 12,0-41,0 nmol / l.
If the indicators are within normal limits, then the child is likely to be completely healthy. Do not worry if the numbers in the results of the tests go beyond the limits of the norm: the triple test is very often "mistaken". In addition, there are a number of factors that seriously affect the results of biochemical research:
- multiple pregnancies;
- ECO;
- weight of the pregnant woman (in full women, the indices are increased, in the case of lean ones, they are lowered);
- bad habits (smoking during pregnancy);
- diabetes mellitus in pregnant women;
- incorrect definition of the gestational age.
Experiencing about possible pathologies of the fetus is not worth it. No doctor has the right to make a diagnosis, let alone interrupt pregnancy, on the basis of screening. The results of the studies allow only to assess the risk of having a child with congenital defects. Women with high-risk appoint additional tests (detailed ultrasound, amniocentesis, cordocentesis).