Hydrops Fetalis Caused by Congenital Syphilis: Case Series and a Comprehensive Review

A total of 30 hydropic fetuses, including 25 cases from published reports and 5 from our own series, were reviewed, validated, and analyzed. This review yielded the following key findings: (1) Unlike most cases of nonimmune hydrops fetalis (NIHF), hydrops caused by syphilis is not only preventable but also treatable, with complete resolution possible when appropriately managed. (2) Syphilis-associated hydrops carries a poor prognosis if timely and appropriate treatment is not administered. (3) Based on limited data, intravenous penicillin G is probably more effective than intramuscular benzathine penicillin in treating hydropic fetuses. (4) Middle cerebral artery peak systolic velocity (MCA-PSV) measurements are increasingly used as a reliable and noninvasive tool for assessing fetal anemia, determining the need for intrauterine transfusion (IUT), and monitoring treatment response. (5) A significant number of cases did not receive prenatal treatment due to false-negative serologic results caused by the prozone effect, as well as the omission of syphilis from the differential diagnosis of NIHF, leading to missed prenatal diagnoses. (6) IUT may help mitigate cellular damage in developing vital organs caused by anemic hypoxia, particularly while awaiting the effects of medical treatment. In conclusion, the modern approach to managing this ancient disease includes: (1) prioritizing intensive intravenous penicillin G therapy over conventional intramuscular benzathine penicillin G; (2) utilizing MCA-PSV in conjunction with other indicators of anemia to monitor its severity; and (3) implementing IUT to prevent anemic hypoxic injury in cases where the hematocrit falls below 30%.