Bowel perforation with a serendipitous revelation: A case report on a rare developmental anomaly

During fetal development, the dorsal mesentery of the ascending colon and descending colon gets resorbed, and both the right colon and the left colon get attached to the posterior and lateral parietal peritoneum by the 5 th month of gestation. Failure of fixation can lead to persistent colonic mesentery. In case of the left colon, this developmental variant is termed as persistent descending mesocolon (PDM), which is an uncommon congenital anomaly. PDM is associated with right-sided sigmoid colon and medialization of the descending colon, medial to the left renal hilum. PDM has multiple clinical and surgical implications, especially in patients who undergo left hemicolectomy. It is also associated with prolonged surgical time during left hemicolectomy due to variant vascular anatomy and associated multiple congenital adhesions. Few studies also suggest that PDM is associated with anastomotic failure in patients who undergo left hemicolectomy. Pre-operative identification of this anatomical variant would help the surgeon in optimal planning of the surgery and also helps in prognostication.