Modulation of the gut microbiota as a novel strategy to prevent anastomotic leak after colorectal surgery: Systematic scoping review.

BACKGROUND

Anastomotic leak (AL) remains a major source of morbidity following colorectal surgery. Increasing evidence implicates the gut microbiome in the pathogenesis of AL, with certain microbial species disrupting tissue repair through collagen degradation. Perioperative modulation of the microbiome may offer a novel strategy to improve anastomotic healing. This scoping review aimed to map available evidence on microbiome-targeted interventions, synthesise mechanistic insights, and identify translation gaps in relation to anastomotic outcomes.

METHODS

A systematic scoping review was performed. MEDLINE, Embase and Cochrane Central Registry of Controlled Trials databases were searched from database inception to 5th August 2025. Studies were eligible if they investigated perioperative interventions that modulated the gut microbiome and evaluated anastomotic healing or leak rates. Both clinical and preclinical studies were included. A narrative synthesis was performed by charting key findings.

RESULTS

Of 4209 records screened, 27 studies met the inclusion criteria: 9 clinical and 18 preclinical. Interventions included bowel preparation, probiotics, synbiotics, arginine/omega-3 supplementation, dietary modification, faecal microbiota transplantation (FMT), phosphate, tranexamic acid, morphine and infliximab. Among clinical studies, only oral antibiotics combined with mechanical bowel preparation were associated with a significant reduction in leak rates. Preclinical studies showed interventions such as high-fibre diets, FMT, rectal tranexamic acid and phosphate supplementation improved anastomotic healing via enhanced microbial diversity, suppression of pathogenic organisms, or inhibition of collagenolytic activity.

CONCLUSION

This review highlights a range of microbiome-targeted interventions with potential to reduce AL. While clinical evidence remains limited, several preclinical strategies demonstrate promise and warrant evaluation in early-phase human trials.