Influence of simethicone added to the rinse water during colonoscopies on polyp detection rates: results of an unintended cohort study

Simethicone is a common antifoaming agent that is added to endoscopic rinse solutions, but data regarding its effect on polyp detection rates is lacking. In this study, we report the effect of discontinuation of this practice on polyp detection rates.Procedure data of 4,254 consecutive colonoscopies were used. Patients underwent standard bowel preparation with polyethyleneglycol (Glycoprep®). Colonoscopies were performed utilising Olympus EVIS EXERA III, CV-190 equipment, while quality data (withdraw times, polyp detection rates, quality of bowel preparation) was assessed utilising an endoscopy reporting system (Provation®). Following an educational event that highlighted that simethicone may form deposits in the channels of endoscopes, the practice to add simethicone (InfacolR, Nice Pak) to the auxiliary channel water pump was abandoned, but endoscopists were not notified about this change. After 5 days and performing 75 colonoscopies, the change of practice was identified and addition of simethicone recommenced.The discontinuation of simethicone use reduced the polyp detection rate from 55% (95% CI 53-56) to 45% (95% CI 34-56, 1-sided, p = 0.028); the polyp detection rate returned to the pre-intervention levels of 55% (95% CI 52-58) upon resumption of normal practice.The addition of simethicone to the auxiliary water pump during colonoscopy results in a 10% increase in polyp detection rates