Abdominal complete hydatidiform mole following uterine evacuation: a case report

Hydatidiform mole (HM) is a form of gestational trophoblastic disease that most commonly develops within the uterine cavity. Ectopic hydatidiform mole is exceedingly rare, and abdominal implantation represents one of its rarest presentations. Due to nonspecific clinical manifestations and the lack of characteristic imaging features, abdominal HM poses significant diagnostic challenges and is frequently diagnosed only after surgical exploration.

We report the case of a 24-year-old woman with a history of polycystic ovary syndrome who conceived following ovulation induction therapy. She was diagnosed with complete hydatidiform mole and underwent uterine evacuation. Postoperatively, serum human chorionic gonadotropin (hCG) levels failed to decline appropriately and subsequently rebounded. Imaging studies revealed no definitive intrauterine lesions, but a persistent mass was detected posterior to the uterus. Diagnostic laparoscopy identified an isolated lesion located in the rectouterine pouch and rectal peritoneum, without any communication with the uterine cavity or adnexa. The lesion was completely excised laparoscopically. Histopathological examination demonstrated hydropic swelling of chorionic villi with diffuse trophoblastic proliferation, and immunohistochemical analysis revealed absence of p57^KIP2 expression, confirming the diagnosis of abdominal complete hydatidiform mole. Following surgery, serum hCG levels rapidly declined and returned to normal. The patient recovered uneventfully and remained under close postoperative hCG surveillance, with no evidence of persistent or recurrent disease.

Abdominal complete hydatidiform mole is a rare but important diagnostic consideration in patients with persistent or rising serum hCG levels after molar evacuation. This case highlights the limitations of imaging modalities and underscores the critical role of postoperative hCG monitoring in the early detection of ectopic molar disease.