When is the唐氏筛查 performed?
Disease description:
After becoming pregnant, various examinations are required, such as the Down syndrome screening (triple test). I would like to ask the doctor, at which week is it best to undergo the Down syndrome screening?
Doctor's answer (1)
Dr. Zhao Xiaodong
Down syndrome screening, also known as prenatal screening for Down syndrome, is an important test during pregnancy used to assess the risk of fetal chromosomal abnormalities such as Down syndrome. Regarding the timing for Down syndrome screening, there are several key points to note:
1. **First-trimester screening**: Usually performed between 9 weeks and 13 weeks + 6 days of pregnancy, with the optimal time being between 10 and 12 weeks. During this period, the thickness of the fetal nuchal translucency (NT value) is primarily assessed by color ultrasound, combined with serological test results for risk assessment.
2. **Second-trimester screening**: Usually performed between 15 weeks and 20 weeks + 6 days of pregnancy, with the optimal time being between 16 and 18 weeks. During this period, maternal venous blood is primarily collected to measure the concentrations of serum markers such as alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol, combined with factors such as maternal age, weight, and gestational age for risk assessment.
