Abstract
PURPOSE: Anastomotic leakage (AL) remains a serious complication following low anterior resection (LAR) for rectal cancer. Although several risk factors for AL have been identified, the role of preoperative anal sphincter function remains unexplored. We hypothesized that elevated maximum resting pressure (MRP) and maximum squeeze pressure (MSP), measured preoperatively via anorectal manometry (ARM), might increase AL risk by inducing functional outlet obstruction. METHODS: This single-center retrospective cohort study included patients who underwent LAR without a diverting stoma between January 2010 and December 2015. We analyzed the associations between preoperative ARM parameters and early major AL events. Independent predictors of AL were also identified. Receiver operating characteristic curve analysis was performed to evaluate the predictive value of ARM parameters for AL. RESULTS: Among 1,396 patients, early major AL occurred in 41 (2.9%). Patients with AL demonstrated significantly higher median MRP (55.7 vs. 42.6 mm Hg, p = 0.001) and MSP (186.5 vs. 150.3 mm Hg, p = 0.008) values. Multivariable analysis revealed that higher MRP (odds ratio [OR], 1.021 per mm Hg increase; 95% confidence interval [CI], 1.004-1.039; p = 0.017) and shorter tumor distance from the anal verge (OR, 0.815 per cm; 95% CI, 0.718-0.925; p = 0.002) were independent predictors of AL. An optimal MRP cutoff value of 55.65 mm Hg yielded 53.7% sensitivity and 75.1% specificity (area under the curve, 0.657). CONCLUSION: Preoperative MRP is an independent predictor of early major AL after LAR. Elevated resting anal pressure may create functional outlet obstruction, increasing intraluminal pressure at the anastomotic site and compromising healing. Preoperative ARM could identify high-risk patients who may benefit from protective interventions.