Which test is used for syphilis screening in prenatal labs?

• A. HCG
• B. HepBsAg
• C. RPR
• D. Rubella IgG

Answer: (C)

Screening for syphilis in prenatal care uses a non-treponemal serologic test, chosen for rapid, inexpensive, broad screening. The Rapid Plasma Reagin (RPR) test detects antibodies to a cardiolipin-containing complex and is used to screen pregnant patients. If the result is positive, a treponemal-specific test (such as FTA-ABS or TPPA) confirms infection, since non-treponemal tests can be falsely positive in pregnancy or other conditions. In prenatal labs, all pregnant women are screened early to prevent congenital syphilis, and RPR’s speed and cost-effectiveness make it the standard initial screen. The other options measure pregnancy status (HCG), hepatitis B status (HepB surface antigen), or rubella immunity (Rubella IgG), not syphilis.