Association between anastomotic leak after rectal resection and bowel dysfunction, a systematic review, meta-analysis and meta-regression.

Anastomotic leak (AL) after colorectal anastomosis can be a risk factor for bowel dysfunction, namely low anterior resection syndrome (LARS). The present study aimed to assess bowel dysfunction in patients who developed AL after anterior resection compared to patients without AL. We conducted a PRISMA-compliant systematic review of PubMed, Scopus and Cochrane Library for randomized and observational studies investigating the association between AL after anterior resection and bowel dysfunction. The main outcomes were LARS, faecal incontinence and urgency. Pairwise meta-analyses were conducted to calculate the relative risk (RR) of the study outcomes and their 95% confidence intervals (CI). This review included 20 retrospective studies comprising 4764 patients (61.6% male, median age 63 years). AL was detected in 14% of patients and those who experienced AL had a higher risk of LARS (six studies; 1329 patients, RR: 1.27 95%CI: 1.02, 1.58, p = 0.035), major LARS (seven studies; 1395 patients, RR: 1.38, 95%CI: 1.07, 1.79, p = 0.012), urgency (five studies; 955 patients, RR: 1.15, 95%CI: 1.04, 1.27, p = 0.005) and had higher LARS scores (seven studies; 1450 patients, WMD: 6.64, 95%CI: 3.76, 9.52, p < 0.001) and Wexner incontinence scores (seven studies; 1045 patients, WMD: 1.72, 95%CI: 0.16, 3.28, p = 0.031). Based on low to moderate certainty evidence, AL after colorectal and coloanal anastomoses was significantly associated with an increased risk of LARS, particularly major LARS, urgency and higher LARS and Wexner/Cleveland Clinic Florida-Fecal Incontinence Scores.