Question

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

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

Hint:

Quad test is a second-trimester screen, done at 15-20 weeks.

Answer 1

The Correct Option is C

Step 1: Place the quad test on the screening calendar. It is a second-trimester blood test, so it falls after the first-trimester combined screen. Step 2: The four markers it checks are AFP, hCG, unconjugated estriol, and inhibin A, used to estimate risk of Down syndrome, trisomy 18, and open neural tube defects. Step 3: The recommended timing is 15 to 20 weeks of gestation, which matches option c, with the sweet spot often quoted around 16 to 18 weeks. Step 4: Options offering 8 to 15 weeks belong to first-trimester or dual screening, and they are too early for accurate quad-marker interpretation, so the best answer is 15 to 20 weeks. \[\boxed{15-20 \text{ weeks}}\]