A 36-year-old, previously healthy, parous woman was admitted as a gynaecological emergency with an 8-day history of dull and constant pain in the left lower abdomen. The onset was insidious. The pain was associated with constipation, radiated to the small of the back and was aggravated by movement. The woman complained of loss of appetite and there was no significant relieving factor.She had had a normal menstrual period 3 weeks before admission. Six years prior to this episode she had undergone a second-trimester, prostaglandin-induced termination of pregnancy. Expulsion of the products of conception was incomplete. Evacuation of the uterus and immediate laparoscopic tubal sterilisation using one clip on each tube were carried out. Two years later she attended the outpatient department with complaints of pelvic pain and deep dyspareunia. On physical examination at that time there was tenderness in the suprapubic region and the anterior vaginal fornix. The clinicians arranged a diagnostic laparoscopy but she did not attend and was discharged from follow-up.On examination at the time of her index admission the patient was in moderate discomfort. Her temperature was 37.6ºC. Her lower abdomen was markedly tender. She required opioid analgesia to allow further examination. There was guarding in the lower abdomen but no rebound tenderness. On palpation a firm, very tender midline mass, possibly arising from the pelvis, was felt. This extended up to the umbilicus and had restricted mobility. Bimanual examination was extremely uncomfortable and there was cervical excitation tenderness. The uterus felt enlarged but the exact size was difficult to define because of tenderness. The patient's haemoglobin level was 10.5 g/dl. Neutrophils and monocytes were elevated and lymphocytes were decreased on differential white cell count of blood. A urine specimen contained a trace of protein and a urine pregnancy test was negative. There were no significant pathogens in a high vaginal swab and an endocervical swab was negative for chlamydia. An abdominal ultrasound scan revealed a 6 × 10 cm thick-walled, septated, cystic mass extending from above the fundus of the uterus along the anterior abdominal wall.In view of the acute symptoms and the abdominal mass, an urgent exploratory laparotomy was arranged. Entry into the peritoneal cavity was difficult. Because the mass was densely adherent to the parietal peritoneum and the urinary bladder, the rectus muscles were difficult to mobilise from the midline. To minimise risk of inadvertent entry, the urinary bladder was filled with methylene blue solution. Needle aspiration of stained fluid revealed that the urinary bladder was adherent up to midway between the symphysis pubis and the umbilicus. Above this level the surgeon could enter the peritoneal cavity. When the rectus muscles were retracted laterally the mass ruptured, releasing pus. A Filshie clip was found within a pus-filled cavity of about 8 cm diameter with thick walls. The mass was also adherent to the bladder dome and the omen...