Bowel Prep in Colorectal Surgery--What Is the Best Approach?

Albert B. Lowenfels, MD


May 23, 2019

What is the best bowel preparation before colorectal surgery to avoid postoperative complications? Using stored data of subjects (N = 27,804) from the American College of Surgeons National Surgical Quality Improvement Program, the authors of a recent paper published in Annals of Surgery[1] compared four different approaches:

  • No preparation: 23%

  • Mechanical bowel prep (MBP) only: 33%

  • Oral antibiotic prep (ABP) only: 6%

  • Both MBP and ABP: 38%

All patients received intravenous antibiotics prior to surgery. Patients with prior infection, anesthesia class V poor-risk patients, patients requiring emergency surgery, and patients with missing data were excluded.

The results showed significant benefit for those patients receiving both preoperative MBP and ABP treatment (P < .001 for all outcomes). These benefits included reduced surgical-site and organ-space infection, less frequent wound dehiscence, and less frequent anastomotic leakage. There was no evidence that combined preoperative MBP and ABP increased the risk for Clostridium difficile infection.

Where Does This Study Leave Us?

Throughout most of the 20th century, mechanical bowel prep along with oral antibiotics was a widely used method to promote bowel sterility before colon and rectal excision. Since that time, there have been numerous trials either confirming or questioning the individual or combined use of a mechanical bowel prep or oral antibiotics.[2,3]

What does this recent report add? First, it reveals that with various preoperative strategies available to them, 38% of surgeons in this large sample rely upon oral antibiotics combined with preoperative bowel cleansing. In contrast, only 23% of surgeons preferred no preoperative treatment.

Although the results clearly favor dual preoperative preparation, there are several caveats. The chief problem is that this was not a randomized trial; the authors attempted to select similar patients in the various groups, a less robust method than a randomized trial. Also, it is not clear that infections appearing after hospital discharge would have been captured. Finally, less than half of all patients undergoing colorectal surgery in the entire database were included in this study, raising the possibility of selection bias.

The results do agree with recent guidelines from colorectal surgical groups about the benefit of the combined use of MBP and ABP.[4] Bottom line: This report provides some additional evidence for the combined use of MBP and ABP.

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