S0188 Complete Elimination of Gas Insufflation by Insertion and Withdrawal Water Exchange Reduces Post-Colonoscopy Flatulence: A Double Blinded Observational Study

INTRODUCTION: Conventional colonoscopy generates aerosol, which disseminates bacteria [Chapman, BMJ 2001] during and after the procedure, in part related to air insufflation-induced flatus SARS-CoV-2 is present in the gut tissue and feces During the COVID-19 pandemic, mitigation of aerosol-mediated infection is desirable Total water exchange colonoscopy (TWEC - insertion and withdrawal water exchange) eliminates the need for air insufflation We test the hypothesis that TWEC reduces flatus compared with other methods that rely on gas insufflation METHODS: This study was a retrospective analysis of prospectively collected data from a sample of outpatient screening and surveillance colonoscopies at a single endoscopy unit over a 2-month period Six colonoscopists used different techniques (Table 1) Since evaluation of flatus during colonoscopy cannot be blinded, we assumed that flatus after colonoscopy during the recovery period is an accurate reflection of flatus peri-procedurally, and has the distinct advantage that blinded assessment was feasible Data on flatulence during recovery were collected by a nurse blinded to colonoscopy techniques Colonoscopists did not know which patients were selected for flatus monitoring Sample size calculation [TWEC 1%, other intervention 39%] yielded 14 per group, 28 total per colonoscopist IRB approval was waived because recovery monitoring was a routine part of post-colonoscopy care RESULTS: 168 consecutive colonoscopies (28 per endoscopist) were identified Patient age, BMI and procedure indication (screening/surveillance) were comparable (data not shown) Compared to techniques where gas was used during any part of the examination, significantly fewer patients (P < 0 01) were observed to pass flatus during recovery in the TWEC group (Table 2) CONCLUSION: In a recent letter to the editor (Adv Dig Med, in press) we expressed the opinion that TWEC (avoiding gas insufflation) seems to be a logical, cost-conscious, and easily implemented safeguard to reduce SARS-CoV-2 transmission in addition to more widely accepted protective measures We now provide double blinded observational data to support this opinion By eliminating the use of gas during colonoscopy, TWEC appears to reduce peri-procedural flatus, and by inference, aerosol formation This may have potential impact on mitigating the risks of aerosol-induced infection during colonoscopy in the era of COVID-19