Rare case of peritoneal complete hydatidiform mole.

A 23-year-old woman, gravida 1, para 1, was transferred to our hospital with acute lower abdominal pain and vital signs consistent with shock. Her urine concentration of human chorionic gonadotrophin was 8000 mIU/mL. Transvaginal ultrasound revealed an echo-free space with mosaic echo pattern in the right adnexal area and no gestational sac in the uterus. With a preoperative diagnosis of ruptured ectopic pregnancy, emergency laparotomy was performed. The rectouterine pouch was filled with many clots containing small amounts of villous tissue. After removal of the conceptus, which was infiltrating into the peritoneum of the Pouch of Douglas, bleeding was controlled by Argon laser. Histological examination of the conceptus by immunohistochemical staining with p57(kip2) showed features of complete hydatidiform mole. This case demonstrates that the peritoneum in the Pouch of Douglas is a possible site of ectopic complete hydatidiform mole occurrence and that immunohistochemical stain is useful to confirm the diagnosis of ectopic complete hydatidiform mole.