Background & Objective: Colonoscopy serves as a diagnostic and therapeutic tool for children. However, the process of bowel preparation presents a considerable challenge. This study aimed to compare the effectiveness of a clear liquid diet (CLD) versus a low-residue diet (LRD) in bowel preparation for colonoscopy among children aged 2-14 years.
Materials & Methods: In this single-blind clinical trial, a total of 110 children aged 2-14 years undergoing colonoscopy were randomly assigned to two groups: the CLD group and the LRD group. Along with their assigned diets, all participants received 2 g/kg of polyethylene glycol in two or three divided doses, as well as a single dose of 5-mg bisacodyl prior to colonoscopy. The primary outcome was the adequacy of bowel cleansing for colonoscopy, evaluated using the Boston Bowel Preparation Scale (BBPS) in both groups. The secondary outcomes included the tolerability of bowel preparation diets and adverse effects.
Results: According to the physician’s assessment, the CLD group had favorable BBPS scores (BBPS ≥5) in 96.5% (55/57) of cases, while the LRD group had favorable scores in 98.1% (52/53) of cases. There were no significant differences between the two groups in terms of the mean BBPS score, regimen tolerability, and adverse effects. 
Conclusion: This study demonstrated that both CLD and LRD regimens were effective in bowel preparation and were well-tolerated by children aged 2-14 years.