The birth of a healthy child is the natural desire of every pregnant woman. But, unfortunately, the hopes for happy motherhood are not always fulfilled. About 5% of newborns have various congenital diseases. Screening in the 1st and 2nd trimesters of pregnancy allows us to determine the extent of the risk of congenital abnormalities in the fetal.
Currently, there are fairly effective methods of prenatal diagnosis of many fetal diseases that can be identified from 11 weeks of pregnancy. Timely screening examinations make it possible to detect a wide range of fetal abnormalities and see ultrasound signs of chromosomal anomalies.
What is early prenatal screening and when is it done?
Screening is a set of tests that identify groups of pregnant women who are at risk of having a baby with chromosomal abnormalities and birth defects. But early screening is only the initial, preliminary stage of screening, after which women who have been identified as being at risk for congenital anomalies are recommended for a more detailed diagnostic examination that will accurately confirm or rule out the presence of abnormalities.
This diagnostic test is carried out in pregnant women at 11-13 weeks +6 days (when the fetal coccyoptic-parietal dimension is between 45 and 84 mm). The most optimal time for screening is between 12 and 13 weeks, as this examination assesses both the signs of chromosomal abnormalities in the fetus and the anatomical structures of the future child and at 11 weeks – 11 weeks +4 days it is very difficult.
What does early prenatal screening include
The comprehensive screening includes:
- Ultrasound examination of the fetus for markers (signs) of chromosomal abnormalities and congenital malformations;
- Determination of the level of biochemical markers of chromosomal abnormalities in the blood of a pregnant woman: beta hCG and PAPP-A. The study is conducted using special high-tech equipment of Cobas e, Roshe, authorized for calculation of the risk of chromosomal syndromes in the Astraia program (FMF);
- uterine artery Dopplerometry;
- cervicometry – measurement of the length of the cervix;
- history taking (age, height, weight, number of pregnancies and births, smoking, diabetes mellitus, arterial hypertension, etc.)
- measurement of blood pressure in both arms.
The data obtained: anamnesis, ultrasound and biochemical markers are placed in a specially developed program Astraia, which calculates the risk of birth of a child with congenital anomalies. The combination of these studies increases the efficiency of detecting fetuses with Down syndrome and other chromosomal diseases.
Early prenatal screening can calculate the following risks:
- Down syndrome (trisomy 21) in the fetus;
- Edward syndrome (trisomy 18) in the fetus;
- Patau syndrome (trisomy 13) in the fetus;
- Risk of early (before 34 weeks) and late (after 37 weeks) pre-eclampsia in the pregnant woman. Learn all about pre-eclampsia here
What is assessed by a first-trimester ultrasound scan
1- Fetal Coccyoparietal Dimension (FCD)
This reading accurately determines the gestational age (pregnancy), especially if the woman can’t remember the first day of her last menstrual period, or if her menstrual cycle is irregular. In the report, gestational age is determined by fetal NT and not by the date of the last menstrual period.
2- Markers of chromosomal abnormalities:
- The thickness of the collar space (TVP) is a major sign of chromosomal abnormality in the fetus. An increase in NTT greater than the 95th percentile for each gestational age is considered abnormal. Each increase in NTD increases the risk of fetal chromosomal abnormality.
- Nasal bone Fetuses with Down syndrome may have no nasal bone or a reduced nasal bone (hypoplasia). Very rarely this can also occur in perfectly healthy children. The exact diagnosis can only be determined by genetic testing.
- Blood flow in the venous duct is a small vessel in the fetal liver. If there is a reverse (retrograde) blood flow in this vessel we can assume that the fetus has a chromosomal syndrome or a congenital heart defect.
- Blood flows through the tricuspid valve into the fetal heart Retrograde (reverse) blood flow here also indicates a chromosomal abnormality or can be seen in congenital heart disease.
3- fetal anatomical structures and exclusion of major birth defects
4- Cervical length
5- Walls of the uterus and appendages (ovaries)
6- Blood flow in the uterine arteries
What to do if there is a high risk of chromosomal abnormality in the fetus
If the set of early antenatal check-ups reveals a high risk of fetal congenital pathology, we recommend that you consult a geneticist, followed by invasive diagnostics (chorionic villus sampling before 14 weeks or amniocentesis performed after 16 weeks) and a genetic test. It is the genetic analysis that determines the exact chromosomal diseases and congenital abnormalities of the fetus.
