Context

Colonoscopy is a valuable diagnostic and therapeutic tool in colon cancer screening and prevention. Earlier studies have reported higher failure rates and lower adenoma detection rates among patients undergoing colonoscopy in the afternoon,1 2 and poor bowel preparation is considered to be the main cause for these results.2 3 Inadequate bowel preparation can result in longer procedure time, missed lesions and reduced screening intervals, thereby increasing cost and complications. Though there are several factors implicated in successful completion of a colonoscopy, quality of bowel preparation and timing of colonoscopy are considered two modifiable factors4 5 to improve successful completion. Therefore investigators in this study performed a randomised endoscopist-blinded study to compare the efficacy of bowel cleansing with one gallon (4 litres) polyethylene glycol (PEG) in the morning of an afternoon colonoscopy, with that of traditional evening-before regimen.