2025 Volume 78 Issue 7 Pages 292-297
Persistent descending mesocolon (PDM) is characterized by embryologic failure of fusion of the left-sided colon, wherein the descending colon does not fuse with the parietal peritoneum and becomes displaced to the right. The patient was a 76-year-old woman who underwent laparoscopic high anterior resection (D3 dissection) for rectosigmoid cancer. During the procedure, the left-sided colon was deviated to the right side and adherent to the mesentery of the small intestine and appendix, leading to a diagnosis of PDM. Intraperitoneal ligation of the root of the inferior mesenteric artery, inferior mesenteric vein, and left colonic artery (LCA) was performed, and the patient was then transitioned to extracorporeal manipulation. Deficiency of the marginal artery connecting the LCA to the first branch of the sigmoid artery was observed. To prevent colon necrosis, extensive enterectomy was performed, followed by anastomosis after mobilization of the splenic flexure. In cases of PDM, the anatomical characteristics, including the potential for marginal artery defects, should be understood to perform surgery more cautiously and avoid complications.
