A pregnant woman in the third trimester is diagnosed with latent syphilis of unknown duration. She gives a history of anaphylaxis to penicillin. The correct management is:
- A Doxycycline 100 mg BD for 28 days — safe in third trimester
- B Penicillin desensitisation followed by benzathine penicillin G 2.4 MU IM weekly x3 ✓
- C Azithromycin 2 g single dose — alternative for pregnancy
- D Erythromycin 500 mg QID for 30 days and treat infant after birth
Explanation
Penicillin is the ONLY proven treatment for syphilis in pregnancy — no alternative achieves reliable transplacental cure of fetal infection. In penicillin-allergic pregnant women, penicillin desensitisation (oral or IV) is mandatory, followed by benzathine penicillin G 2.4 million units IM weekly for 3 doses (latent syphilis of unknown duration). Doxycycline is contraindicated in pregnancy (third trimester risk of inhibiting fetal bone growth, dental staining). Azithromycin is NOT recommended due to macrolide resistance. Erythromycin does not cross the placenta sufficiently to treat the fetus.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.