Primary Peritoneal Pregnancy Requiring Conversion From Laparoscopic to Open Surgery Due to Massive Hemorrhage: A Case Report.

Ultrasound and magnetic resonance imaging are useful tools for the preoperative diagnosis of peritoneal pregnancy; however, accurate diagnosis before surgery remains challenging. We report a rare case of primary peritoneal pregnancy in which laparoscopic surgery was initiated under the suspicion of tubal pregnancy, but was converted to open surgery due to massive hemorrhage. A 40-year-old female (gravida 1, para 1) was referred to our hospital at six weeks and six days of gestation for suspected ectopic pregnancy. Despite a serum human chorionic gonadotropin (hCG) level of 10,060 mIU/mL, no intrauterine gestational sac was identified. Imaging revealed a gestational sac-like hematoma adjacent to the uterus. Laparoscopic surgery was planned for a presumed tubal pregnancy. Intraoperatively, a gestational sac was found in the pouch of Douglas, leading to the diagnosis of peritoneal pregnancy. During the attempted removal of the trophoblastic tissue, massive hemorrhage occurred, necessitating conversion to open surgery. The total blood loss was 2,450 mL, and a blood transfusion was required. The postoperative course was uneventful, and serum hCG levels declined appropriately after surgery.