High risk of Down syndrome screening - Is amniocentesis required?

Patient's question:

No

Doctor's answer:

Down syndrome, also known as trisomy 21, refers to a condition where the patient has an extra chromosome in the 21st pair (while the normal number is one pair). Down syndrome screening is calculated by measuring the levels of AFP and HCG in the pregnant woman's serum, combined with the mother's age, weight, and gestational age to determine the risk value. The critical value is 1/275. A value greater than this indicates a high risk, while a value lower than this indicates a low risk. The probability of having Down syndrome (DS) in the general population (under 37 years old) is 1/750.