Published online Jun 16, 2019. doi: 10.4253/wjge.v11.i6.413
Peer-review started: April 8, 2019
First decision: May 16, 2019
Revised: June 1, 2019
Accepted: June 10, 2019
Article in press: June 10, 2019
Published online: June 16, 2019
The presence of small air bubbles and foam are an impediment to a successful colonoscopy. They impair an endoscopist’s view and diminish the diagnostic accuracy of the study. This has been particularly noted to be of concern with the switch to lower volume polyethylene glycol (PEG) and bisacodyl combination preparation.
Simethicone is commonly added to water for irrigation during colonoscopy to clear bubbles/ foam and to improve mucosal visibility. However, recent endoscope manufacturer guidelines recommend against intraprocedural irrigation with simethicone infused water due to concerns for its retention in irrigation channels despite reprocessing. Our initial motivation to perform this study was to evaluate whether the addition of liquid simethicone to low volume PEG bowel preparation would improve intraluminal visibility during colonoscopy and thereby eliminate the need for intra procedural irrigation of simethicone.
The primary outcome measurement was the comparison of bubbles and foam utilizing the Intraluminal Bubbles Scale. Secondary outcomes measured include Boston Bowel Preparation Scale measurement, total number of polyps, polyp size differentiation, polyp laterality, total adenoma detection, cecal insertion time, withdrawal time, and adverse events.
This is a prospective, parallel-group, randomized, double-blinded and placebo-controlled study conducted at two gastroenterology community-based outpatient endoscopy centers. Adult participants were instructed to add liquid simethicone to 2-liter split bowel preparation with bisacodyl. Patients, endoscopists, and enrolling staff were blinded during patient enrollment. Endoscopists were also blinded during conduction of the procedure. Intraluminal Bubbles Scale was recorded during the procedure and a grade of 1-4 was allocated correlating with the percent circumference of colonic mucosa clear of all bubbles/foam. Grade 1 was equivocal to > 90% mucosa clear of bubbles not requiring irrigation; Grade 2 was 75%-89% mucosa clear of bubbles not requiring irrigation; Grade 3 was 50%-74% mucosa clear of bubbles and required irrigation; Grade 4 was < 50% mucosa clear of bubbles and required irrigation.
Higher Intraluminal Bubbles grades III and IV (less than 75% of the mucosa cleared of bubbles/foam requiring intervention with simethicone infused wash) were detected in the placebo group [Simethicone n = 4/84 vs Placebo n = 20/84 (P = 0.007)]. BBPS total score was 7.42 (SD = ± 1.51) in the simethicone group and 7.28 (SD = ± 1.44) in the placebo group (P = 0.542) from a total of 9. Significantly higher number of adenomas were detected in the simethicone group (P = 0.001).
The addition of simethicone to bowel preparation is well advised for its anti-foaming properties during colonoscopy. The results of this study suggest that addition of oral simethicone can improve bowel wall visibility and reduce the need for intraprocedural irrigation.
Larger research studies with screening colonoscopy patients should be carried out to evaluate the effect of simethicone on adenoma detection rate.