How much blood is needed for the Down syndrome screening?

Patient's question:

No

Doctor's answer:

The Down syndrome screening requires a blood draw of 2~5ml. The purpose of the Down syndrome screening is to determine the risk level of the fetus suffering from congenital idiocy through blood tests on the pregnant woman. If the results of the Down screen show a high risk of the fetus having Down syndrome, further confirmatory tests should be conducted.