Persistent Descending Mesocolon as a Key Risk Factor in Laparoscopic Colorectal Cancer Surgery

Background: Persistent descending mesocolon (PDM) is a rare colonic anatomical variant. However, PDM's impact on the technical aspects and outcomes of laparoscopic colorectal cancer resection are unclear.

Patients and methods: This retrospective clinical cohort study was conducted at a high-volume cancer center in Japan to evaluate intra- and postoperative outcomes of laparoscopic colorectal cancer surgery in patients with (PDM+) or without (PDM-) PDM over the past 7 years.

Results: Between January 2012 and September 2019, 2,775 patients underwent laparoscopic colorectal cancer resection at our center, including 60 (2.1%) cases of PDM. Preoperative detection was achieved in only 5 patients (8.3%), 39 patients were men, and 21 patients were women. The average age was 67 years. Twenty patients had a history of prior abdominal surgery (33.3%), with little or no subsequent adhesions. The average duration of sigmoidectomy in PDM+ patients (n=17; 217.7±14.2 min) was significantly longer than that in PDM- patients (n=547; 176.2±2.4 min; p=0.003), as was average blood loss (32.3±10.6 ml vs. 16.7±2.8 ml; p=0.03). Likewise, average operative time for high anterior resection in PDM+ patients (n=11; 227.1±20.2 min) was significantly longer than that in PDM- patients (n=294; 195.6±3.0 min; p=0.048). Rates of postoperative anastomotic leakage and postoperative recurrence did not differ in both groups. In PDM+ patients, retention of left colic artery had no impact on proximal specimen margins or occurrences of anastomotic leakage.

Conclusion: PDM prolongs operative times and increases bleeding in laparoscopic colorectal cancer surgery and should be considered a risk factor when encountered.