Successful Management of a Massive Second-Trimester Subchorionic Hematoma: A Case Report

A massive subchorionic hematoma is associated with an increased risk of adverse pregnancy outcomes, including spontaneous abortion, preterm birth, and intrauterine fetal demise. However, current clinical guidelines lack standardized diagnostic criteria and evidence-based management recommendations for massive subchorionic hematomas, particularly during the second trimester. A 34-year-old pregnant woman at 12 weeks and 6 days' gestation presented with acute-onset vaginal bleeding of 1-h duration. Color Doppler ultrasonography revealed an anteriorly located placenta and identified a hypoechoic, well-defined subchorionic collection measuring 109 × 41² mm beneath the chorionic plate of the gestational sac, which was considered a massive subchorionic hematoma at the second trimester. Following written informed consent, intramuscular progesterone was administered to suppress uterine activity, and intravenous cefuroxime was initiated for prophylaxis against infection. Serial monitoring of maternal hemoglobin concentration and subchorionic hematoma dimensions was performed. Following more than 3 months of active fetal surveillance and supportive obstetric management, the patient remained clinically stable. The subchorionic hematoma resolved completely by 28 weeks and 3 days' gestation, and a viable female neonate was delivered by cesarean section at 39 weeks and 1 day's gestation. In conclusion, this study provides a detailed, real-world example of managing a high-risk, massive subchorionic hematoma in the absence of standardized guidelines, which lays a practical foundation for future research.