Oral antibiotics and a low-residue diet reduce the incidence of anastomotic leakage after left-sided colorectal surgery: a retrospective cohort study

Purpose Anastomotic leakage is a potential complication after colorectal surgery. We investigated the effects of oral antibiotics and a low-residue diet on the incidence of anastomotic leakage after left-sided colorectal surgery. Methods Outcomes were retrospectively compared between 64 patients who underwent mechanical bowel preparation alone (group A) and 183 patients who underwent mechanical bowel preparation with addition of oral kanamycin and metronidazole (group B) on the day before left-sided colorectal surgery. After surgery, patients in group A received a normal diet containing dietary fiber and those in group B received a low-residue diet. The primary outcome was the incidence of anastomotic leakage. Secondary outcomes were rates of other postoperative complications, length of postoperative hospital stay, and laboratory data. Results Anastomotic leakage, surgical site infection, and diarrhea were less common in group B than in group A (4.9% vs 18.8%, 6.6% vs 23.4%, and 25.7% vs 43.8%, respectively). Postoperative C-reactive protein levels were significantly lower in group B. The median postoperative hospital stay was significantly shorter in group B than in group A (8 days vs 9 days, P = 0.010). Adaptive double least absolute shrinkage and selection operator regression revealed that use of preoperative oral antibiotics and a postoperative low-residue diet were associated with lower incidence of anastomotic leakage (odds ratio 0.163, 95% confidence interval 0.062–0.430; P < 0.001). Conclusion Oral antibiotics and a low-residue diet reduced the incidence of anastomotic leakage and shortened the postoperative hospital stay by 1 day.