What to do if a pregnant woman is at critical risk for Down syndrome screening

If the Down syndrome screening shows a borderline risk, then women are advised to pay attention to further screening and diagnosis. The diagnosis methods include chorionic villus sampling, biopsy and amniocentesis. Further diagnosis can be made through these tests, and do not rush to define it.

Diagnosis method after high-risk screening for Down syndrome

1. Chorionic villus sampling

Chorionic villus sampling is usually performed in the early stages of pregnancy, approximately between the 6th and 9th weeks of pregnancy. Samples are taken from the uterus to obtain chorionic villus tissue with strong proliferation capacity, and the chorionic villus tissue is then subjected to chromosome analysis and genetic diagnosis. Infant birth defects such as Down syndrome, familial Tay-Sachs disease, cystic fibrosis, etc. can be diagnosed through chorionic villus sampling.

2. Amniocentesis

Amniocentesis is a test that involves extracting 20 ml of amniotic fluid between 16 and 20 weeks of pregnancy, culturing the cells shed by the fetus in the amniotic fluid, and testing the chromosomes of the cells. This invasive test carries the risk of amniotic fluid leakage infection and miscarriage, but the probability of this risk is very low, only about 0.1%. In addition, if you miss the appropriate gestational age, you will no longer be able to do it.

3. Non-invasive DNA genetic testing

Non-invasive prenatal genetic testing is performed in the early or mid-pregnancy, approximately 12 to 24 weeks, by performing B-ultrasound and collecting 5 ml of peripheral blood from the pregnant woman, extracting free DNA, and analyzing to determine whether the status of the fetal chromosomes is normal, with an accuracy rate of 99%. It is non-invasive, has a short cycle, no risk of miscarriage, and is highly accurate. It also provides a new option for pregnant women who do not accept or miss invasive testing.