Background: A two liters low volume polyethylene glycol (PEG) electrolyte solution preparation was proposed for improving patients’ tolerability with either split or non-split dosage cleansing method. Patient compliance, adverse experiences, and cleansing efficacy of each anatomical segment of the colon using both methods should be determined.

Objective: To assess the cleansing efficacy of split dosage versus non-split dosage PEG-electrolyte solution for each anatomical segment of the colon according to the inverted Ottawa bowel preparation scale.

Materials and Methods: The present study was a prospective, randomized, endoscopist-blinded study. Volunteers that underwent elective screening colonoscopy were eligible for recruitment into the present study. Patients having any contraindication for colonoscopy, or the use of PEG-electrolyte solution such as bowel obstruction, intestinal perforation, or toxic megacolon were excluded. Cleansing efficacy was evaluated by the inverted Ottawa bowel preparation scale for each anatomical segment of the colon. Medical adherence and compliance were evaluated. Participants were asked to rate their satisfaction and inform the presence of any adverse experiences related to the bowel preparation method.

Results: Ninety-four volunteers were randomly assigned to two groups. Of these, 46 received the split dosage cleansing method and 48 received the non-split dosages cleansing method. Overall compliance was approximately 94%, comparable for both preparation methods. Average age was 61.5 years for non-split dosage and 60.4 for split dosage group. Satisfaction score in the non-split dosage group was 8.46, which was not significantly different from 8.56 of the split dosage group (p=0.934). Split dosage PEG-electrolyte solution provided comparable degree of cleansing as standard non-split dosages preparation for transverse, descending, sigmoid, and rectum. However, split dosage provided significantly superior

cleansing results over the non-split dosages method for ascending colon at good or excellent with 84.7% versus 47.9% (p<0.01), and caecum at good or excellent for 76.1% versus 41.7% (p<0.01) based on the inverted Ottawa bowel preparation scale.

Conclusion: Split dosage PEG-electrolyte solution method provided significantly superior cleansing results over the non-split dosages method for right-side colon with comparable satisfaction score and rate of adverse events.