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

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.