What is the impact of nutrition interventions on incidence of anastomotic leak after colorectal surgery? A systematic review of randomized trials.

Nutrition-related factors have been associated with increased incidence of anastomotic leak (AL) following colorectal surgery; however, specific perioperative nutrition recommendations remain unclear. This systematic review examined the extent to which perioperative nutrition interventions influence the incidence of AL compared to standard care. On November 4, 2024, we searched Medline, Embase, CINAHL, Scopus, and Google Scholar. Eligible studies were randomized controlled trials involving adults undergoing colorectal surgery for any indication. Interventions included any perioperative nutrition or dietary support versus standard care, and our primary outcome was incidence of AL, defined as a failed surgical anastomosis with leakage of bowel contents. The risk of bias was assessed using the Cochrane tool, and findings were synthesized narratively. Sixteen trials (n = 2013) were included, primarily from Asia and Europe, with most trials (81 %) exclusively recruiting patients undergoing surgery for colorectal cancer. Interventions included probiotics (50 %), parenteral nutrition (25 %), enteral nutrition (6 %), oral nutrition supplements (12 %), and mixed therapies (6 %). A total of 139 (6.9 %) AL events were reported, although most trials (63 %) did not clearly define or explain AL measurement and only one listed AL as the primary outcome. Most trials (81 %) showed no difference in incidence of AL; however, two trials (13 %) saw a reduction, and one trial (6 %) reported an increase. Eight (50 %) trials were at high risk of bias. In conclusion, few low-risk-of-bias trials have evaluated the influence of perioperative nutrition on anastomotic leak. Given the infrequent occurrence of AL, large, adequately powered studies are required to detect meaningful differences. Consequently, current evidence remains insufficient to draw firm conclusions about the role of perioperative nutrition on AL risk.