Mirrored Appearance of Complete Common Mesentery Discovered on CT Scan for Crohn's Disease.

Incomplete 90° intestinal rotation in a clockwise direction results in complete common mesentery being placed in a mirror image to and with a similar appearance to complete common mesentery. This rotation places the colon in the right half of the abdominal cavity and the small intestine in the left half of the abdominal cavity. We report the case of a 19-year-old patient with a history of cerebral palsy secondary to meningitis who presented with melaena and inflammatory anaemia. CT enterography was performed which showed regular, non-stenosing circumferential wall thickening of the sigmoid colon and rectosigmoid junction compatible with Crohn's disease, which was confirmed by pathophysiology. It also revealed transposition of the colon to the right hemi-abdomen and the small intestine to the left hemi-abdomen, the caecum to the right iliac fossa, and the third portion of the duodenum to the left of the mesenteric vessels. LEARNING POINTS: Complete common mesentery in the mirror image is an anomaly of intestinal rotation, placing the colon in the right half of the abdomen and the small intestine in the left half of the abdomen.It can be asymptomatic and discovered incidentally during assessment for other conditions. © EFIM 2021.