Quality and effect of single dose versus split dose of polyethylene glycol bowel preparation for early-morning colonoscopy

Background and study aims: The conventional procedure of ingestion of an entire dose of polyethylene glycol solution on the day before early-morning colonoscopy may result in poor bowel preparation. The aim of this study was to evaluate the efficacy and effect of a split-dose ingestion of polyethylene glycol for early-morning colonoscopy. Methods: A total of 303 age- and sex-matched consecutive individuals presenting for medical check-ups were randomly assigned to receive either 4 L of polyethylene glycol solution with a soft diet on the day before colonoscopy (n = 152; group A), or 3 L of polyethylene glycol solution with a soft diet on the preceding day and then 1 L of the solution on the day of colonoscopy (n = 151; group B). The quality of bowel preparation was evaluated using the Ottawa scale, and the time to cecal intubation and the technical difficulty during the procedure were also recorded. Results: There was no difference in compliance between group A (single-dose) and group B (split-dose). The quality of bowel preparation was better in group B compared with group A. When the participants were categorized according to compliance (good compliance, 116 in group A, 119 in group B; poor compliance, 36 in group A, 32 in group B), the quality of the bowel preparation had a higher score in the good compliance compared with the poor compliance group, and in group B this difference was usually significant. Conclusions: Split-dose bowel preparation with polyethylene glycol solution provided a better quality preparation than the conventional method for patients undergoing early-morning colonoscopy.