Technical risk factors for benign anastomotic strictures in colorectal and/or coloanal anastomosis: A retrospective case–control study

Aim: Anastomotic stricture occurs in up to 30% of colorectal resections; however, evidence on risk factors and preventive measures remains scarce. This study aimed to identify technical factors responsible for increasing the risk for colorectal and coloanal anastomotic strictures. Method: This was a retrospective cohort study of patients with anastomotic stricture who underwent resection and/or redo anastomosis between January 1, 2011 and August 1, 2021 in a tertiary referral centre. Patients with anastomotic stricture were compared with an equal number of randomly selected patients without anastomotic complications, who were operated on during the same time period. The main outcome measures were technical risk factors of anastomotic stricture. Results: Each group included 50 patients who were similar for age, sex, American Society of Anesthesiologists score, distance of anastomosis to the dentate line and indication for surgery. Median follow-up was significantly longer in the non-stricture group (38.6 months vs. 12.6 months, p = 0.04). Splenic flexure mobilization [hazard ratio (HR) = 0.18 [2], 95% CI: 0.08–0.39, p < 0.001], high ligation of the inferior mesenteric artery (HR = 0.22, 95% CI: 0.09–0.5, p < 0.001) and high ligation of the inferior mesenteric vein (HR = 0.21, 95% CI: 0.09–0.50, p < 0.001) were associated with a lower likelihood of anastomotic stricture. Conversely, use of a 25-mm-diameter circular stapler (HR = 22.69, 95% CI: 2.69-191.10, p < 0.001), clinically significant anastomotic leak (HR = 3.94, 95% CI: 2.04–7.64, p < 0.001), firing the stapler more than once for rectal division (HR = 24.75, 95% CI: 6.85–89.38, p < 0.001) and diverting stoma (HR = 3.087, 95% CI: 1.736–5.491, p < 0.0001) were predictive of an anastomotic stricture. Conclusion: Failure to mobilize the splenic flexure and to perform high ligation of the inferior mesenteric vessels were associated with higher odds of anastomotic stricture. A small-diameter circular stapler and multiple distal stapler firings were also associated with anastomotic stricture. These data support routine splenic flexure ligation and high ligation of the inferior mesenteric vessels as well as avoidance of both multiple stapler firings for rectal transection and a 25-mm circular stapler for anastomosis.