EP167 - Systematic Review on the Impact of Perioperative Microbiome-Targeted Interventions on Colorectal Surgery Anastomotic Leaks

Purpose/Background: Anastomotic leak remains a major source of morbidity and mortality following colorectal surgery, with its pathogenesis increasingly linked to changes in gut microbiome and perioperative dysbiosis. Recent studies have demonstrated that perioperative microbiome-targeted interventions, such as probiotics, synbiotics, and selective decontamination of the digestive tract may reduce postoperative infectious complications, though their effect on anastomotic leak rates is less clear and may depend on intervention type and patient factors. Despite these advances, the precise relationship between microbiome modulation and anastomotic healing remains elusive and no prior systematic review has comprehensively synthesized the randomized trial evidence specifically addressing anastomotic leak as an outcome. This review is the first to systematically evaluate all eligible randomized controlled trials investigating the impact of perioperative microbiome-targeted interventions on colorectal surgery anastomotic leaks, addressing a critical gap in the literature and informing future research and clinical practice.

Methods/Interventions: RCTs examining the effects of perioperative microbiome-targeted interventions on colorectal surgery anastomotic leaks were identified using a systematic database search (PubMed, Cochrane Library) according to PRISMA guidelines. Screening and data extraction were conducted by four independent reviewers. Risk of bias was assessed using the revised Cochrane risk of bias tool (RoB 2).

Results/Outcomes: A total of 8 studies were included. Across these studies, perioperative microbiome-targeted interventions included probiotics, mechanical bowel preparation or oral antibiotics. These interventions consistently reduced overall postoperative infectious complications in colorectal surgery, but their impact on anastomotic leak rates was variable. Three studies examining oral antibiotic decontamination found significantly reduced rates of anastomotic leak in comparison to two trials which found no difference in anastomotic leak. However, it should be noted that each study utilized different antibiotic regimens, and some were single-agent trials while others used a combination. Among studies of probiotics, one study found a significant reduction in anastomotic leak, while two found no difference. Again, each study utilized a unique regimen of probiotics, including cultures and timing of administration. The single study examining use of mechanical bowel prep alone found no difference in the rate of anastomotic leak. Two studies examined antibiotic effects on the microbiome, however these effects were variable and were not directly correlated with changes in rates of anastomotic leak.

Conclusion/Discussion: Preoperative microbiome-targeted strategies show consistent benefit in reducing infectious complications after colorectal surgery, while their effect on anastomotic leak remains promising but variable. Thus far, antibiotic decontamination demonstrates the most consistent benefit for anastomotic leak prevention while the data on probiotics remains mixed. These findings highlight microbiome-targeted strategies as a modifiable factor in surgical recovery and underscore the need for larger, well-designed RCTs to determine the optimal intervention for improving anastomotic healing.