Background <p>Hemorrhagic ascites is a rare manifestation of endometriosis. Here, we present an unusual case in a perimenopausal woman that was successfully managed laparoscopically, and summarize its clinical characteristics to provide guidance for early diagnosis of the disease.</p> Case presentation <p>A 48-year-old Han Chinese woman experienced hemorrhagic ascites for 6 months. During surgery, the uterus was found adhered to the anterior walls of the sigmoid colon and rectum, forming an encapsulated cyst. Laparoscopic hysterectomy and bilateral oophorectomy were performed, with histopathology confirming endometriosis. The patient recovered well after surgery.</p> Conclusion <p>This case emphasizes the importance of excluding malignant tumors. Diagnosis relies on surgical pathology. For perimenopausal or postmenopausal women, total hysterectomy with bilateral adnexectomy is recommended to reduce the risk of recurrence and malignant transformation.</p>