Question

What is the best time to perform the quadruple (quad) test?

• A. 8-12 weeks
• B. 11-15 weeks
• C. 15-20 weeks
• D. 18-22 weeks

Hint:

It is a second-trimester serum screen.

Answer 1

The Correct Option is C

Step 1: Place the test in its trimester; the quad test is a hallmark of second-trimester serum screening.
Step 2: Its optimal window is $15$ to $20$ weeks, when the four analytes give the most accurate risk estimate for Down syndrome and open neural tube defects.
Step 3: Earlier ranges ($8$ to $12$ and $11$ to $15$ weeks) are first-trimester territory, and $18$ to $22$ weeks runs past the ideal point. The $15$ to $20$ week band fits best.
\[\boxed{\text{15 to 20 weeks}}\]