Abstract:

Persistent descending mesocolon(PDM) refers to the failure of the descending mesocolon to fuse with the lateral or posterior abdominal wall peritoneum by the end of the fifth month of pregnancy. This condition is characterized by the descending colon moving towards the midline or to the right, adhesions and shortening of the descending mesocolon, rightward displacement of the inferior mesenteric artery (IMA) with a higher incidence of multiple branches sharing a common trunk, and the inferior mesenteric vein lying closely adjacent to the marginal vessels, among other anatomical features. PDM may increase the difficulty of laparoscopic colorectal cancer surgery and the risk of colonic ischemia and postoperative anastomotic leakage. Here we discuss the embryological etiology, anatomical characteristics, diagnosis and classification, and strategies for laparoscopic colorectal cancer surgery in the presence of PDM, based on the author's practical experience. Understanding the variations in the course of the intestinal tract, adhesion characteristics, and vascular branching patterns of PDM can improve preoperative diagnostic rates, facilitate preoperative planning, and ensure the protection of blood supply to the intended resection margins during surgery. During laparoscopic colorectal cancer surgery, attention should be paid to adhesiolysis between the descending mesocolon and the ileocecum in right-sided colon cancer cases. In left-sided rectal cancer cases with concomitant PDM undergoing D3 surgery, preserving the origin of the inferior mesenteric artery and dissecting the No. 253 lymph nodes may reduce the risk of colonic ischemia.

Key words: Colorectal neoplasms, Persistent descending mesocolon, Intestinal malrotation, Persistent ascending mesocolon, Colonic ischemia