Persistent Descending Mesocolon as An Intraoperative Risk Factor in Laparoscopic Surgery for Left‐Sided Colon and Rectal Cancer

Abstract

Introduction Persistent descending mesocolon (PDM) represents a failure of fusion of the descending mesentery, leading to anatomical abnormalities. This study aimed to examine the effects of anatomical features of PDM on laparoscopic surgical outcomes. Methods Patient backgrounds, surgical outcomes, anatomical characteristics, and operative findings were retrospectively compared between 186 patients classified into PDM and non‐PDM groups who underwent primary resection for left‐sided colon and rectal cancer at our hospital from January 2019 to December 2020. Results PDM was diagnosed in nine patients (4.8%). The operative time (337 ± 165 vs 239 ± 107 min, p = 0.010) was significantly different between PDM and non‐PDM groups, but bleeding loss was not different (108 ± 97 ml vs 53 ± 142 ml, p = 0.259). In PDM patients, in addition to abnormal fixation of the sigmoid‐descending colon junction, adhesion of the mesentery of the colon and small intestine in 100%, and adhesion between the mesocolon in 33% patients was confirmed intraoperatively. Ileus was more common in the PDM group (two cases, 22%) and in the non‐PDM group (10 cases, 5.6%), but there was no significant difference in overall postoperative complications between the two groups (p = 0.215). The duration of postoperative hospital stay (28 ± 20 vs 16 ± 11 days, p = 0.002) was significant between the two groups. The left colonic artery (LCA) could not be preserved in six patients in the PDM group, one of whom had anastomotic leakage and two of whom required additional resections due to intraoperative intestinal blood flow failure. Conclusion PDM prolonged operative times and duration of postoperative stay in laparoscopic surgery for left‐sided colon and rectal cancer. Division of the LCA in PDM patients should be considered an intraoperative risk factor for injury to the marginal artery.

Vascular anatomical study of persistent descending mesocolon in patients undergoing laparoscopic surgery for colorectal cancer

“…The exact cause of the variations in the vascular running direction in PDM cases remains unknown, but they may be related to the displacement of the left‐sided colon and the shortening of the colonic mesentery. In PDM, the lack of fixation of the descending mesocolon to the dorsal abdominal wall during the fifth month of gestation results in the medial movement of the descending colon 1–9 . This medial displacement of the descending colon is also expected to cause a concomitant displacement of the sigmoid colon to the right, therefore PDM is sometimes called a “right‐sided sigmoid colon”, 6 resulting in a right‐sided traveling deviation of the SA in such cases.…”

“…The anatomic features of PDM can clarify the importance of preoperative evaluation of vascular anatomy in patients with PDM. PDM is characterized not only by fixation abnormalities but also by anatomical variations, such as the shortening of the mesentery 1–12 . The shortening of the mesentery results in a closer than usual proximity of the marginal vessels with the arteries involved in lymph node dissection, that is, IMA, LCA, and SA 3,4,8–10,12 .…”

“…Regarding short‐term outcomes in laparoscopic colorectal surgery for PDM, studies reported various results 3–7 . Wang et al 6 reported that PDM cases increased blood loss and prolonged operative times than non‐PDM cases.…”

“…Persistent descending mesocolon (PDM), the surgical findings of which were initially reported in 1960 by Morgenstern, 1 is a rare congenital atypia of fixation of the descending colon. In a patient with PDM, the descending to sigmoid colon is displaced medially toward the right side of the abdomen and adheres to the small intestinal mesentery or right pelvic wall 1–12 . PDM shows no Toldt's fusion fascia because the descending mesocolon does not fuse with the retroperitoneum, which results in the shortening of the left‐sided colonic mesentery 8 .…”

Persistent descending mesocolon as a vital risk factor for anastomotic failure and prolonged operative time for sigmoid colon and rectal cancers

“…Persistent descending mesocolon (PDM) is a congenital disease rst reported by Morgenstern in 1960 [1]. The incidence of PDM varies from 1.3-4.0% [2][3][4]. For patients with PDM, the descending colon is often medially located toward the failed fusion with the dorsal abdominal wall.…”