A very rare case of endometriosis presenting with massive hemoperitoneum.

Endometriosis is a cause of acute abdomen because of the leakage or rupture of endometriotic cyst and tubo-ovarian abscess. However, massive hemoperitoneum as a cause of acute abdomen with endometriosis is very rare. We herein present a case of a 48-year-old woman who was urgently referred to our clinic with colic, abdominal distension, and hypovolemic shock during menstruation. Ultrasonography revealed massive hemorrhagic ascites. Exploratory laparoscopy was urgently performed to achieve hemostasis. The volume of hemoperitoneum evacuated from the pelvis was 1,890 mL. Although the uterus and bilateral ovaries were normal, fresh bleeding was observed from endometriosis on the left cul-de-sac peritoneum, and hemostasis was successfully performed. The potential occurrence of hemorrhagic shock associated with endometriosis, depending on the implantation site, needs to be recognized.