Obstetrics & Gynecology>>>>>Preconception Counseling, Genetics, and Prenatal Diagnosis
Question 7#

A 30-year-old G1P0 at 8 weeks’ gestation presents for her first prenatal visit. She has no significant past medical or surgical history. A 29-year-old friend of hers just had a baby with Down syndrome and she is concerned about
her risk of having a baby with the same problem. The patient reports no family history of genetic disorders or birth defects.

In order to increase the detection rate for Down syndrome in the first trimester, you may also offer her which of the following tests in addition to the NT measurement?

A. α fetoprotein (AFP) serum screening
B. First trimester screen, which includes biochemical testing with serum markers PAPP-A and free or total β-hCG, along with maternal age
C. Amniocentesis
D. Inhibin level serum screening
E. Fetal echocardiogram

Correct Answer is B

Comment:

Several large, multicenter trials have shown that, in the first trimester, a combination of NT measurement, maternal age, and serum markers (PAPP-A and free or total β-hCG) is a reliable test for Down syndrome, with a detection rate of approximately 84%. Serum AFP is available as a screen for NTDs, and should be ordered after 15 weeks. Inhibin level alone is not a screen for Down syndrome, but may be part of a Quad screen. Amniocentesis cannot be offered until the second trimester. Fetal echocardiogram is not reliable in the first trimester, may not show cardiac defects in the first trimester, and is not considered a screening test for Down syndrome. It may be ordered in fetuses suspected to have Down syndrome based on abnormal diagnostic testing