EP04.11: Placenta/liver/spleen changes in fetuses exposed to maternal syphilis infection

Syphilis infection (SI) triggers an inflammatory response in the host, often exacerbated after treatment with the release of Treponema pallidum byproducts. There is limited information on the longitudinal effects of SI exposure on fetal organs. The aim of this study is to report on changes in the placenta, liver, and spleen in fetuses suspected to have congenital syphilis (CS). Prospective study of 52 pregnant subjects diagnosed and treated for SI according to the CDC 2021 guidelines. Serial ultrasound (US) scans were performed >20 weeks gestation either prior to, or within 7 days of indicated treatment, and thereafter every 4 weeks until delivery. Only 42 (81%) cases underwent follow up US evaluation. Placenta thickness was measured at the site of cord insertion and placentomegaly defined as > 2 standard deviations; liver length in a coronal plane of the fetal abdomen, from the lower edge of the right lobe to the highest point in the right diaphragm dome, and hepatomegaly defined as > 95th percentile; spleen circumference in a cross-sectional plane of the abdomen with the spleen visible behind the stomach, and splenomegaly was defined as >95th percentile. All measurements were plotted according to available reference standards. Placentomegaly was observed in 46.1% of cases, 8/52 (15.3%) at first scan, 38% (16/42) developed placentomegaly throughout gestation, and 4 cases resolved during pregnancy. Hepatomegaly was observed in 38% (10/52) of fetuses at first scan, 10/42 (24%) developed hepatomegaly during pregnancy, and 5 fetuses showed normalisation of liver size. Splenomegaly was observed in 7 cases (13%), 3/52 at first scan, 4 developed splenomegaly throughout gestation, and 2 showed normalisation of the spleen size. Approximately 46% of fetuses with suspected CS demonstrated an inflammatory response detected by sonographic evaluation, manifested as either placentomegaly, hepatomegaly, or splenomegaly. This response may be related to exposure time, treatment response, or reinfection.