Different methods have been suggested for better bowel preparation before performing a colonoscopy. Persistence of fecal matter in the lumen would cause imperfect procedure, diagnostic delay, and need to repeat the colonoscopy. This study was designed to compare two methods of bowel preparation with split doses or single-dose of Polyethylene Glycol (PEG).

A total of 200 patients who were candidate for colonoscopy enrolled in this study. These patients had no history of opium usage in any forms. They randomly allocated into two groups to receive a single dose of PEG (4 liters) over the night before the colonoscopy schedule (single dose group, N=100) or one dose in the night before and another in the morning of the colonoscopy (split-dose group, N=100). Colon preparation was scored based on the Ottawa preparation scale. To analyze the results, chi-square test was used for qualitative variables and t-test for quantitative variables. All statistical analyzes were performed using SPSS-16 software.

Mean Ottawa score was 0.85 in right colon, 0.60 in mid colon and 0.73 in recto sigmoid, in the split-dose group. While in the single dose group, mean Ottawa score was 0.78 in right colon, 0.70 in mid colon and 0.80 in recto sigmoid. The differences in right, mid, the recto-sigmoid and total score were not statistically significant between two groups.

This study showed no preference between single-dose and split-dose of PEG for bowel preparation in non-addicted patients.