Difficult diagnosis: internal herniation of the terminal ileum through the foramen of Winslow into the lesser sac.

Herniation of the bowel through the foramen of Winslow is rare and accounts for 8% of all internal herniae. It typically presents clinically and biochemically as small bowel obstruction. It carries a high mortality as diagnosis is often delayed, despite bowel strangulation, as clinical signs are not typical and imaging may not be diagnostic. In the case presented here, a healthy 25-year-old man was admitted with sudden onset right-sided abdominal and back pain. He denied vomiting, and had opened his bowels. His bloods were normal and venous lactate <2; CT was not diagnostic. At laparotomy, he was found to have internal herniation of the terminal ileum through the foramen of Winslow, which was gangrenous and required resection. This paper discusses the difficulty in diagnosing internal herniation and poses the question as to whether we are too dependent on CT findings in the setting of an acute abdomen. 2015 BMJ Publishing Group Ltd.