Split-Dose Versus Standard Single-Dose Bowel Preparation Regimens for Colonoscopy: A Systematic Review and Meta-Analysis

Adequate bowel preparation is essential for colonoscopy. While split-dose regimens may improve cleansing by shortening the interval to the procedure, the comparative efficacy of split-dose regimens versus single-dose regimens remains under investigation. This meta-analysis evaluated whether split-dose bowel preparation is superior to single-dose regimens for adequate cleansing and polyp detection. We systematically searched PubMed, EMBASE, Web of Science, and Cochrane CENTRAL through February 20, 2026, for randomized controlled trials (RCTs) comparing split-dose versus single-dose preparation in adults undergoing colonoscopy. The primary outcome was adequate bowel preparation rate, and the secondary outcome was polyp detection rate. A random-effects model with the Hartung-Knapp-Sidik-Jonkman (HKSJ) method was used to pool risk ratios (RRs). Five RCTs (n=1,004) were included, of which only two studies were eligible for primary outcome synthesis. Split-dose preparation was associated with a numerically higher adequate cleansing rate (RR=1.24; 95% HKSJ CI: 0.67-2.31; P=0.32; I²=67%). Polyp detection showed a similar non-significant trend (RR=1.42; 95% CI: 0.14-14.67; P=0.68; I²=65%). A supplementary meta-analysis of three studies reporting continuous scores demonstrated significantly better cleansing with split-dose regimens (standardized mean difference = 0.85; 95% CI: 0.22-1.48; P=0.03). A split-dose preparation significantly improved cleansing quality on continuous scales, but the pooled analysis of adequate preparation rates showed a non-significant trend. However, the evidence was limited by heterogeneous outcome reporting.