Isolated Ascending Colon Gangrene With Persistent Ascending Mesocolon: A Case Report.

Persistent mesocolon is a rare embryological anomaly that occurs when the primitive dorsal mesocolon fails to fuse with the posterior lateral parietal peritoneum allowing for volvulus of the cecum and colon. In malrotation of the gut, the normal rotation of the embryonic gut is arrested or disturbed during in-utero development. To our knowledge, this is the first case of isolated colon gangrene with persistent ascending mesocolon to be reported, although earlier studies have documented cases of persistent mesocolon of both ascending and descending mesocolon. This case had signs of acute intestinal obstruction and peritonitis, and preoperative imaging was suggestive of sigmoid volvulus. Explorative laparotomy revealed a hugely dilated and gangrenous ascending colon; the fixed part of the small intestine was found in the subhepatic space, and the hepatic flexure was at a level below the transpyloric plane in the midclavicular line. Findings were suggestive of isolated colon gangrene with persistent ascending mesocolon and malrotation of the gut. Right hemicolectomy with terminal ileostomy was performed and postoperative follow-up showed no complications. For a young patient with no prior co-morbidities, a volvulus of ascending mesocolon diagnosis was deemed unlikely because ascending colon is a retroperitoneal organ. The medial position of ascending mesocolon and small bowel loops to the right side was a crucial intra-operative clue for diagnosis. Such cases are difficult to diagnose pre-operatively through imaging alone, hence explorative laparotomy becomes necessary. Intra-operative findings led to performing a right hemicolectomy and ileostomy to relieve the obstruction. Therefore, among other congenital reasons for intestinal obstruction, surgeons should consider persistent mesocolon and volvulus as differential diagnoses when evaluating young patients. Emergent surgery is the only approach to address this.