28.08 Bowel Preparation with Antibiotics Decreases Surgical-Site Infection for Both Left & Right Colectomy

A. J. Hjelmaas1, A. Kanters1, R. Anand1, J. Cedarbaum1, Y. Chen1, L. Ly1, N. Kamdar1, D. Campbell1, S. Hendren1, S. Regenbogen1  1University Of Michigan,Michigan Medicine,Ann Arbor, MI, USA

Despite recent studies demonstrating the effectiveness of mechanical bowel preparation with oral antibiotics for decreasing rates of surgical site infections (SSI) after colectomy, there remains inconsistency in practice with particular controversy over the role of bowel preparation in right-sided resections. Generally, bacterial concentration and stool solidity increases with progression through the colon, and there persists a belief that bowel preparation is needed only for left-sided resections. To understand whether there is heterogeneity in the efficacy of bowel preparation, we evaluate rates of SSI by the anatomy of resection and type of bowel preparation.

We conducted a retrospective cohort study of patients who underwent elective colorectal resection with anastomosis and without stoma between 2012 and 2015, using prospectively-collected data from the Michigan Surgical Quality Collaborative, a state-wide consortium encompassing 73 community, academic, and tertiary hospitals. MSQC nurse reviewers collect a variety of colectomy-specific processes of care, including the type of bowel preparation – mechanical preparation with antibiotics, mechanical preparation without antibiotics, and no bowel preparation. We categorized resections by type of anastomosis according to CPT code – ileocolic (IC), colo-colonic (CC), or colorectal (CR); then compared the incidence of SSI between bowel preparation subtypes. We compared adjusted rates of SSI using logistic regression, including known patient-specific risk factors for SSI.

A total of 6192 patients were included in the study. 1134 underwent IC anastomosis, 3537 underwent CC anastomosis, and 1521 underwent CR anastomosis. Adjusted comparisons are shown in the Figure. For all cases, adjusted rates of SSI were 8.3% for no bowel preparation, 7.1% for mechanical preparation, and 4.6% for mechanical preparation with antibiotics (p<0.001). For right-sided colectomy, the adjusted rates of postoperative SSI were 11.1%, 5.4%, and 5.1% for no prep, mechanical prep, and mechanical prep with antibiotics, respectively (p=0.005).

As in previous studies, we find overall rates of SSI are lowest when mechanical preparation is used in conjunction with oral antibiotics. Contrary to the assumption that bowel preparation is unnecessary for right colectomy, we found that bowel preparation led to significantly fewer SSIs even among resections with ileocolic anastomosis. This finding will reinvigorate efforts in our statewide collaborative to encourage bowel preparation with antibiotics for all colorectal resections.