Does hindgut not rotate? Descending colon transposition and persistent ascending mesocolon: clinical implication and...

The positional anomaly of the intestine is rare in adult patients, which poses challenges to clinical practice and surgery. We report a female patient diagnosed with low rectal cancer, who was found to have a right-sided retroperitoneal descending colon, right-sided sigmoid colon, and a persistent intraperitoneal ascending mesocolon, a combined anomaly never previously documented. The anomaly was not identified until laparoscopic investigation, which led to manipulation difficulties and a compromised extent of the surgical resection. The embryological basis of this rare anomaly is postulated to be an abnormal 180° rotation of the hindgut following the return of the midgut loop, resulting in the descending colon occupying the normal position of the ascending colon. This hypothesis challenges the conventional understanding of intestinal development and warrants further investigation.