Outcomes of cases with complete hydatidiform mole coexisting with a fetus: A single-center study

Background Complete hydatidiform moles coexisting with a fetus (CHMCF) are uncommon. Although CHMCF is associated with perinatal complications and post-molar gestational trophoblastic neoplasia (GTN), necessitating post-delivery chemotherapy, live birth remains feasible. This report presents 14 cases of CHMCF in Japan. Methods We reviewed medical records of patients with CHMCF treated at our hospital from 2000 to 2020 and summarized clinical data, including maternal age, pregnancy details, delivery outcomes, fertility treatments, serum human chorionic gonadotropin (hCG) levels, and ultrasonography findings. Results Fourteen cases of CHMCF were diagnosed. The average age of the mothers was 30.6 years, with the majority conceiving following fertility treatment. The mean gestational age at diagnosis was 12 weeks. Six patients maintained their pregnancies, leading to two live births through emergency cesarean section. Eight patients exhibited spontaneous regression following treatment and pregnancy interruption, achieving negative serum hCG levels within 17.4 weeks. Six patients experienced post-molar GTN, including the two who had live births. One patient presented with FIGO stage I disease, while five patients had stage III lung metastases. All patients received chemotherapy, averaging nine courses, achieving remission within 13.7 weeks. Conclusion The occurrence of GTN was higher after CHMCF than after typical complete hydatidiform moles. Despite the heightened risk of premature birth, some patients with CHMCF who maintain their pregnancies can successfully deliver live babies. Informed consent is essential for patients with CHMCF when considering pregnancy continuation. A team approach involving gynecological oncologists, obstetricians, and neonatologists is essential for effective diagnosis and treatment.