How many weeks is the best to do Down syndrome screening?

I believe that pregnant women should have a certain understanding of Down syndrome, especially those who have experienced it. They are very afraid of Down syndrome because it is related to the future and health of the fetus after birth. Therefore, it is important to do relevant examinations during pregnancy to rule out the possibility of Down syndrome. So, which week is the best time to do Down syndrome screening?

In which week is it best to do Down syndrome screening?

1: Down syndrome screening is done around 17 weeks to check for abnormalities. Down syndrome screening is usually done at 16-18 weeks of pregnancy. It takes more than 2 weeks to cultivate somatic cells. If there is a problem, amniocentesis should be scheduled around 20 weeks, and the results will take about 3-4 weeks. After 20 weeks, it is too late for this screening.

2: When doing B-ultrasound, the biparietal diameter of the fetal head, the brachiocephalic diameter and the length of the femoral head can be measured to estimate the gestational age and calculate the date of delivery (this method is mostly used by doctors for B-ultrasound examination and diagnosis). Medicine often uses the first day of the last menstrual period as the starting time for calculating the expected date of delivery, so the doctor calculated it to be 17 weeks on September 22. The method is different.

Down screening refers to a special testing method that is aimed at special groups that do not have any corresponding disease signs (such as all pregnant women). Through testing, key subjects who are most likely to suffer from a certain disease are selected for subsequent diagnosis-related examinations. One thing that needs to be established is that the purpose of screening is not to diagnose a certain disease, but to select people who are very likely to have a certain disease.

The current screening and diagnosis of Down syndrome, trisomy 18 and congenital neural tube defects is a systematic approach. First, for all pregnant women, the pregnant women with a higher risk of having their fetuses suffer from congenital idiocy, tongue-throwing dementia and other three diseases are screened out through the screening method, and the next step of diagnosis-related examinations is carried out. If the fetus is finally diagnosed with these congenital diseases, the pregnant woman can make her own decision whether to get pregnant again.

The above-mentioned diseases usually use the same screening method, that is, based on your age, weight, AFP and β-HCG levels in your venous blood, combined with some other conditions (such as whether you smoke or drink alcohol, etc.), the risk of your fetus suffering from the above three congenital diseases is calculated. Depending on the risk score you will get a positive (high risk) or negative (low risk) result.

The actual method is to draw chorionic blood or amniotic fluid of the pregnant woman for cell culture, and then do chromosome karyotype analysis. If the 21-trisomy syndrome map is found, the fetus can be diagnosed with Down syndrome. 2. The Chinese name of AFP is alpha-fetoprotein. If the AFP levels in the mother's blood and the amniotic fluid of the fetus are elevated, it is confirmed that the fetus has a neural tube defect, namely spina bifida, meningocele, anencephaly, microcephaly, and hydrocephalus.