When Is a Diverting Stoma Indicated after Low Anterior Resection? A Meta-analysis of Randomized Trials and Meta-Regression of the Risk Factors of Leakage and Complications in Non-Diverted Patients

Background: Anastomotic leak (AL) is a potentially life-threatening complication after low anterior resection (LAR). This meta-analysis aimed to compare outcomes of LAR with and without diverting stoma and to determine factors associated with AL in non-diverted patients. Methods: This was a PRISMA-compliant systematic review of electronic databases (PubMed, Scopus, and Web of Science). Randomized controlled trials comparing LAR with and without diverting stoma were included. Main outcome measures were AL, complications, and operation time in the two groups and risk factors of AL in non-diverted patients. Results: Nine randomized control trials (RCTs) (946 patients; 53.2% male) were included. The diverting stoma group had lower odds of complications (OR: 0.61, 95%CI: 0.461–0.828; p < 0.001), AL (OR: 0.362, 95%CI: 0.236–0.555; p < 0.001, I² = 0), abscess (OR: 0.392, 95%CI: 0.174–0.883; p < 0.024, I² = 0), and reoperation (OR: 0.352, 95%CI: 0.222–0.559, p < 0.001, I² = 0) than the no-diversion group. Both groups had comparable odds of bowel obstruction, surgical site infection, and perioperative mortality. The weighted mean operation time in the diverting stoma group was longer than the no-diversion group (WMD: 34.804, 95%CI: 14.649–54.960, p < 0.001). Factors significantly associated with AL in non-diverted patients were higher body mass index (BMI), ASA ≥ 3, lower tumor height, neoadjuvant therapy, open surgery, end-to-end anastomosis, and longer operation time. Conclusions: Non-diverted patients with increased body mass index, high American Society of Anesthesiologists scores, low rectal cancers, received neoadjuvant therapy, underwent open surgery, end-to-end anastomosis, and longer operation times were at a higher risk of AL after LAR.