A Case of Latent Syphilis in Early Pregnancy: An Incidental Finding at Seven Weeks Gestation

Treponema pallidum, the bacteria that causes syphilis, is typically acquired through sexual contact but can also be transmitted transplacentally (through the placenta), causing congenital infection. Syphilis in pregnancy is a major contributing factor to perinatal morbidity and mortality. Untreated neonates may develop complications affecting the central nervous system, bones, joints, teeth, eyes, and skin. This report highlights the incidental discovery of syphilis in an asymptomatic 22-year-old primigravida (pregnant for the first time) at seven weeks gestation through a positive Treponema pallidum hemagglutination assay and treponemal antibody test during routine antenatal screening, while testing negative for human immunodeficiency virus (HIV). A rapid plasma reagin (RPR) test confirmed the infection with a titer of 1:32, though her partner tested negative for syphilis and HIV. She had a genital rash five months ago treated by a gynecologist in Thailand and remained asymptomatic. The patient was managed with benzathine penicillin G 2.4 million units intramuscularly once weekly for three weeks. Three months post-treatment, the RPR titer decreased to 1:16; however, the patient developed pre-eclampsia and required a cesarean delivery at 30 weeks and five days. Before delivery, the titer increased to 1:32. To prevent congenital syphilis, she received one prenatal and two postnatal benzathine penicillin G injections. The newborn was born without deformities, as confirmed by comprehensive evaluation, and follow-up revealed a successful reduction of the RPR titer to 1:8 three months postpartum. This case underscores the importance of routine antenatal screening for early syphilis detection and treatment, even in asymptomatic patients, to prevent maternofetal complications.