Background : Good bowel preparation improves the rate of polyp detection and the time of caecal intubation during colorectal cancer (CRC) screening.~Suboptimal bowel preparation can results in adenoma miss rate up to 42% (95% CI, 35-49) and advanced adenoma miss rate up to 27% (95% CI, 17-41) The European Society of Gastrointestinal Endoscopy (ESGE) Guideline recommends a split regimen of 4L of polyethylene glycol (PEG) solution (or a same-day regimen in the case of afternoon colonoscopy) for a routine bowel preparation and the delay between the last dose of bowel preparation and colonoscopy should be minimized and no longer than 4 hours.~The investigators hypothesize that the addition of water enema to the standard PEG bowel preparation could provide the better quality of bowel preparation and then result in improvement in the rate of adenoma detection among participants scheduled for CRC screening with preparation to procedure interval > 8 hr.~The purpose of this study is to compare the preparation quality using Ottawa Bowel Preparation Scale between the standard PEG preparation and the addition of water enema in participants scheduled for CRC screening. The secondary aim is to compare the effect of the standard PEG bowel preparation and the addition of water enema in terms of adenoma detection rate, the completeness of the examination, total and withdrawal time, safety and adverse events among those scheduled for CRC screening.
The purpose of this study is to compare the preparation quality by using Ottawa Bowel Preparation Scale between the standard PEG preparation and the addition of water enema in participants scheduled for CRC screening