Does mechanical bowel preparation really prevent complications after colorectal surgery depending on the lesion localization? A myth or fact?

Objectives: Despite being routinely used before elective colorectal surgery in most surgical clinics, mechanical bowel preparation (MBP) remains controversial. This study aimed to investigate postoperative complications and outcomes of right, left, or rectosigmoid resection without MBP. Material and Methods: Patients who underwent elective colorectal surgery without mechanical bowel preparation and oral antibiotics between January 2011 and December 2021 were included in the study. Patients were categorized according to the side of resection, and these subgroups were compared for anastomotic leakage, surgical site infections (SSI), and overall morbidity measured using the Clavien-Dindo complication grade. Results: Data of 422 patients were analyzed. Overall anastomotic leakage was found in 14 patients (3.3%), SSI in 46 (10.9%), collection in 14 (3.3%), mortality in 18 (4.3%), and reoperation in 17 (%4) patients. Anastomotic leakage was observed in six (3.9%) in right colectomy, two (1.9%) in left colectomy, and in six (3.7%) patients in the rectosigmoid resection group when the groups were evaluated separately. There was no statistical difference between the groups (p= 0.630). Furthermore, there was no statistical difference between the groups regarding collection and reoperation (p values were p= 0.31, and p= 0.251, respectively). Conclusion: Study results showed that anastomotic leakage, surgical site infection, intra-abdominal collection, reoperation, and mortality rates were similar to the current literature obtained from the studies with mechanical bowel preparation. In addition, these results were found to be similar according to the resection site.