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Syphilis in Pregnancy
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7. Treatment of Syphilis in Pregnancy
Case Scenario 3
D. F. is a 21 y/o G4P1 at 14 weeks gestation who has NOB labs that reveal a positive RPR at a titer of 1:8 with a negative FTA. She has no history of STD and her physical exam is normal. How should you manage?
Treatment of Syphilis in Pregnancy
Penicillin is the only effective treatment for syphilis in pregnancy because other antibiotics do not adequately penetrate into the fetal compartment. Patients who have a history of penicillin allergy require desensitization (see below). Even with appropriate penicillin therapy, up to 10 per cent of infants will be found to have active disease after birth. This underscores the difficulty in treating this infection during pregnancy, the importance of strict adherence to the therapeutic regimen, and why alternative therapies cannot be relied upon to prevent fetal death. It should also be remembered that treatment may result in an acute febrile reaction due to a host response to rapid lysis of the spirochetes accompanied by a release of their cell wall products into the circulation. This is referred to as “the Jarisch-Herxheimer reaction”. This may result in preterm contractions or worrisome fetal heart rate changes. It may be treated with hydration and antipyretics, or steroids if necessary, but should not prevent or delay appropriate therapy.
It should be remembered that all the treatment recommendations detailed below are based on over 50 years clinical experience, not on data from randomized controlled trials.
Primary syphilis (chancre present, low titer, no history of previous treatment), or secondary syphilis (rash, lymphadenopathy, alopecia, condylomata lata, high titer), may both be treated with long acting benzathine penicillin (LA Bicillin) 2.4 million units IM as a single dose. Some authorities recommend a second dose one week later. Sexual partners should be treated with this same therapy if not allergic to penicillin.
Latent syphilis (positive serology without other evidence of disease) is the stage most practitioners will commonly see. Early latent syphilis (<1 year duration) can be treated with the same regimen as early syphilis, one injection of LA Bicillin. However, since it is often difficult to determine the exact duration of infection, it is most commonly treated the same as late latent (>1 year duration) syphilis. For HIV negative patients, the recommended treatment is a total of 7.2 million units of benzathine penicillin, administered as three doses of 2.4 million units IM each at one-week intervals. As noted above, patients who have previously been treated may have persistent low titers for life. If documentation of their prior treatment can be obtained, they do not need to be retreated. Nevertheless, it is probably prudent to repeat their titers in 2-3 weeks looking for a two-tube dilution (fourfold) change in titer to be sure they have not been reinfected. What if the patient misses one of her weekly doses? In non-pregnant patients, if no more than 10-14 days have elapsed since the last injection, therapy may be continued. In pregnant women however, missed doses are not considered acceptable, and the full course of therapy must be repeated.
Neurosyphilis is not commonly seen in obstetric practice. It requires a significantly higher dose of penicillin to adequately penetrate the CNS. The currently recommended regimen is 10-14 days of therapy with either intravenous aqueous penicillin or intramuscular procaine penicillin. Details of all the current CDC recommendations can be found in the MMWR supplement, “Sexually Transmitted Diseases Treatment Guidelines 2002” (Vol. 51, No.RR-6).
