Colonoscopy preparation regimens are poorly tolerated, requiring the use of a large volume of an unpalatable solution and diet restriction for adequate cleansing. The aim of this study was to compare the efficacy of two regimens of bowel preparation before colonoscopy: a whole dose of polyethylene glycol electrolyte solution (PEG-E), with diet restriction vs. a split dose with no diet restriction.

A total of 141 patients (ages 20-84 years, 81 men) were randomly assigned to receive either 4 L PEG-E, along with a liquid diet the day before colonoscopy (Group A) or 2 L PEG-E with a regular diet the day before colonoscopy followed by another 2 L PEG-E on the day of the procedure (Group B). The quality of the preparation was graded by the endoscopist (poor to excellent), who was blinded to the type of preparation. Tolerability of the assigned preparation and adverse effects were recorded by an independent investigator by using a questionnaire administered before colonoscopy. Intra- and interobserver variability was studied by using randomly chosen videotapes of colonoscopies performed as part of the study.

There were 73 patients in Group A and 68 patients in Group B. The quality of the preparation was significantly better in Group B (p=0.011). The tolerability of the preparation regimen was not different overall between study groups in terms of side effects (except for bloating, which was more frequent in Group B, p=0.039) or willingness to repeat the preparation. There was a nonsignificant trend toward improved adherence to the assigned preparation in favor of Group B (p=0.062). Inter- and intraobserver variability analysis showed good to excellent correlation among endoscopists.

Colonic preparation with split-dose PEG-E and no dietary restriction provides better quality colon cleansing than whole-dose preparation, with no significant impact on patient tolerability and side effects.