Is the early pregnancy Down syndrome screening accurate?

Patient's question:

No

Doctor's answer:

Down syndrome screening can generally detect 60%-80% of Down syndrome children and 85%-90% of neural tube defects. A risk factor below 1/270 only indicates a lower risk and does not guarantee complete exclusion, but from the detection rate, the significance of Down syndrome screening is still very great. The best time for the test is between 14-20 weeks of pregnancy. You are now 19 weeks pregnant and should do it as soon as possible.