Split-dose of 4l PEG was used before and on the day of colonoscopy

Three times-dose of 4l PEG was used before and on the day of colonoscop of 4l PEG was used before and on the day of colonoscopy

All patients were given oral instruction for bowel preparation on the day of appointment and re-instruction through phone call on two days before scheduled colonoscopy. They were instructed to have a regular lunch and take only clear liquid or low-residual food for the dinner on the day before colonoscopy. The participants began to drink the first 2 L of PEG at 7:00-9 PM on the day before colonoscopy at a rate of 250 mL every 15 minutes. On the day of the procedure, patients took the remaining 2 L 4-6 hours before colonoscopy.

Adequacy of bowel preparation quality was defined as a total score ≥6 and each segmental score ≥2. The total scores included 3 scores of colonic regions: the right side, the transverse section, and the left side, which ranged from 0 to 9 (0= very poor, 9=excellent). For the unreached colon in incomplete colonoscopy, the segmental BBPS was scored as 0. The total and segmental scores were judged through videos by investigators who were familiar with the criteria and blinded to group allocation.