Adequate bowel preparation is crucial for high-quality colonoscopy. Although oral laxative-based regimens remain the standard, they are often poorly tolerated by frail patients. Colon Wash, a retrograde colonic irrigation technique, has emerged as a potential alternative. This study aimed to compare the efficacy and tolerability of Colon Wash with standard oral low-volume osmotic preparations .

In this single-center observational study, adults undergoing colonoscopy were included. Overall, 160 patients received Colon Wash and 250 received standard oral low-volume osmotic preparations. After 1:1 nearest-neighbor propensity score matching for age, sex, BMI, abdominal surgery, and performance status, 150 patients per group were analyzed. Bowel cleansing quality was assessed using the Boston Bowel Preparation Scale (BBPS). Adequate preparation was defined as a total BBPS ≥6 with ≥2 in all segments.

Adequate bowel cleansing was achieved in 86% of Colon Wash patients and 88% of those receiving standard oral low-volume osmotic preparations (p=0.732). Colon Wash was associated with significantly fewer preparation-related side effects (0% vs. 22%, p<0.001) and a higher cecal intubation rate (100% vs. 92%, p<0.001). No complications occurred in the Colon Wash group. Nausea was the most frequent adverse event with standard oral low-volume osmotic preparations (22%).

Colon Wash provided comparable efficacy and superior tolerability versus standard oral low-volume osmotic preparations. It represents a valid alternative for bowel cleansing and warrants consideration for wider clinical adoption.