The Role of Bowel Preparation in Colorectal Surgery

Results of the 2012-2015 ACS-NSQIP Data

Aaron L. Klinger, MD; Heather Green, MS; Dominique J. Monlezun, MD, PhD, MPH; David Beck, MD; Brian Kann, MD; Herschel D. Vargas, MD; Charles Whitlow, MD; David Margolin, MD


Annals of Surgery. 2019;269(4):671-677. 

In This Article


There were 64,357 patients with bowel preparation data and 27,804 subjects met the study criteria. Of these 5471 (23.46%) received no preparation, 7617 (32.67%) received MBP only, 1374 (5.89%) received ABP only, and 8855 (37.98%) received dual (MBP + ABP) preparation. The demographics and patient comorbidities are shown in Table 1. On average, those patients who had a SSI were younger, had a higher BMI, were more likely active smokers, and had a higher ASA class. In addition, patients with SSI were more likely to have diabetes, ascites, hypertension, disseminated cancer, and to be on chronic steroid treatment.

In modified forward and backward stepwise regression augmenting a doubly robust propensity score-adjusted multivariable regression using patients receiving no bowel preparation as the reference, those receiving dual preparation were less likely to develop a SSI [odds ratio (OR) = 0.39, P < 0.001], organ space infection (OR = 0.56, P < 0.001), anastomotic leak (OR = 0.53, P < 0.001), or wound dehiscence (OR = 0.43, P = 0.001). Compared to unprepped patients, those treated with dual preparation were also less likely to develop C. difficile infection (OR = 0.53, P = 0.035). Combined preparation patients were also less likely to have an unplanned return to the operating room (OR = 0.70, P < 0.001) and had a shorter length of stay in days (β = −0.66, P < 0.001) (Table 2).

Oral antibiotic preparation alone was also compared to no preparation. Patients receiving ABP had lower odds of SSI (OR = 0.63, P = 0.001), organ space infection (OR = 0.59, P = 0.005), and anastomotic leak compared to those receiving no preparation. ABP patients also had a shorter length of stay in days than unprepped patients (β = −0.43, P = 0.004). ABP had no statistically significant differences compared to no preparation in frequency of C. difficile, wound dehiscence, or unplanned reoperation. Mechanical preparation did not show any significant difference in primary outcomes compared to no preparation (Table 2). Individual ABP and MBP were then compared to combined preparation. Antibiotic preparation and MBP alone resulted in more SSI (OR = 1.61, P = 0.002) than combined MBP/ABP and there was a higher leak rate when comparing MBP to dual prep (OR = 1.60, P < 0.001) (Table 3).

Stratified analysis for colon surgery alone was then performed. Compared to no preparation, MBP/ABP patients again had less SSI (OR = 0.35, P < 0.001), organ space infection (OR = 0.56, P < 0.001), anastomotic leak (OR = 0.33, P= 0.004), wound dehiscence (OR = 0.54, P = 0.026), C. difficile (OR = 0.60, P < 0.001), and unplanned reoperation (OR = 0.70, P < 0.001). Likewise ABP alone patients had fewer SSIs (OR = 0.35, P < 0.001), organ space infections (OR = 0.59, P = 0.020), and C. difficile infections (OR = 0.62, P = 0.047) but did not show a difference in anastomotic leak rates, wound dehiscence, or unplanned reoperation (Table 4). Compared to no preparation, dual prep (β = −0.85, P < 0.001), ABP (β = −0.46, P = 0.011), and MBP (β = −0.26, P = 0.013) all were associated with reduced hospital length of stay.

When rectal resections were evaluated independently, MBP/ABP compared to no preparation once again showed lower odds of SSI (OR = 0.49, P < 0.001), organ space infection (OR = 0.53, P < 0.001), wound dehiscence (OR = 0.24, P= 0.005), C. difficile (OR = 0.39, P < 0.001), and unexpected reoperation (OR = 0.68, P = 0.028). There were no significant differences in rates of anastomotic leak however. Outcomes for antibiotic preparation alone in rectal resection was no better than no preparation except for in rates of C. difficile (OR = 0.34, P = 0.007) (Table 5). Dual preparation resulted in lower odds of reoperation (OR = 0.68, P = 0.028), but there were no significant differences in length of stay.