A successful colonoscopy requires the proper preparation of the colon before colonoscopy. Failure to adequately observe the lumen of the colon due to the persistence of fecal matter may lead to diagnostic delay and the need to repeat the procedure. This study was designed to compare the bowel preparation for colonoscopy in opium addicted patients with split doses and single-dose of Polyethylene Glycol (PEG).

A total of 200 patients with opioid addiction were enrolled in this study. They randomly allocated into two groups to receive a single dose of PEG (4 liters) during the night before the colonoscopy (N=100) or two split-doses in the night before and morning of the colonoscopy (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 0.72 in right colon, 0.52 in mid colon and 1.47 in recto sigmoid, in the split-dose group. In the single dose group, mean Ottawa score was 1.12 in right colon, 0.79 in mid colon and 1.12 in recto sigmoid. These differences were statistically significant between two groups (P-value<0.05).

This study showed that in addicted patients, a better bowel preparation for colonoscopy could be achieved when two split-doses are administrated.