A young woman with abdominal distension.

We present the case of a 34-year-old woman with haemorrhagic ascites and an extrinsic rectal mass on endoscopy. Endometrioma was subsequently confirmed by laparoscopy and biopsy. Intestinal endometriosis is common, and often mimics other gastrointestinal pathology. Haemorrhagic ascites or intestinal masses are rare presentations of endometriosis, and this is the only reported case of both occurring together. Endometriosis and ascites are more common in women of African descent, and although histological diagnosis requires laparoscopy, MRI has a high negative predictive value; 95% for intestinal endometriosis. Re-accumulation of ascites were prevented by starting a gonadotrophin antagonist.