A 65-year-old male underwent acute surgery because of a partly ischaemic small intestine due to internal herniation underneath the left external iliac artery. The iatrogenic defect in the peritoneum was created 15 months earlier, when the patient had a robot-assisted radical prostat-ectomy with pelvic lymph node dissection performed. The ischaemic small bowel was resected under a laparotomy, and creation of a temporary stoma was necessary. The peritoneal defect was left open. The patient recovered, and the stoma was surgically closed two months later.