Syphilis in Pregnancy

Syphilis is caused by the spirochete Treponema pallidum subspecies pallidum. During pregnancy, the bacterium can cross the placenta; transmission can also occur at delivery when the infant contacts an infectious maternal lesion. Untreated maternal transmission risk is greater than 70% with primary or secondary disease, approximately 40% with early latent disease, and less than 10% with late latent disease. The risk is therefore greatest in early maternal infection, but no untreated stage is a safe category. Untreated or inadequately treated infection can cause miscarriage, fetal growth restriction, non-immune hydrops, preterm birth, stillbirth, neonatal death, and ocular, neurologic, hepatosplenic, or musculoskeletal disease in a surviving infant. Congenital syphilis rates have risen in Canada, so a single early prenatal screen is not sufficient when repeat testing is indicated by ongoing exposure risk, an outbreak, or provincial or territorial policy. The clinical model is straightforward: the prescriber and specialist establish the maternal stage and regimen; the nurse helps obtain the treatment history and quantitative titres, administers prescribed penicillin safely and on schedule, monitors maternal and fetal status, reinforces follow-up, and communicates urgent changes...