Optimizing bowel preparation regimens for colon capsule endoscopy: an umbrella review (overview of systematic reviews)

Background: Colon capsule endoscopy (CCE) is a minimally invasive alternative to colonoscopy, but its diagnostic performance depends entirely on adequate mucosal cleansing (adequate cleansing rate, ACR) and complete colonic transit (completion rate, CR). These requirements impose stringent preparation demands. Existing systematic reviews (SRs) show substantial heterogeneity in recommendations. Objectives: To identify optimal CCE preparation strategies. Design: Umbrella review (overview of SRs). Methods: A comprehensive literature search was conducted through November 2025 for SRs and meta-analyses (MAs) assessing CCE bowel preparation regimens. Methodological quality was assessed using AMSTAR2, and primary study overlap was quantified using the Corrected Covered Area (CCA). Outcomes included ACR and CR, stratified by preparation components. Results: Fourteen SRs (11 MAs) encompassing 102 primary studies (moderate overlap, CCA 8.59%) were included. Pooled ACR (72.5%–76.8%) and CR (79.8%–83.0%) remained below colonoscopy benchmarks. In inflammatory bowel disease, ACR varied widely (49%–98.5%) with no superior regimen. In the general population, low-volume polyethylene glycol (PEG <4 L) yielded higher ACR (77.5%) than high-volume PEG (72.9%). Sodium phosphate (NaP) boosters outperformed PEG specifically for CR, with NaP + Gastrografin achieving the highest CR (93.1%). Castor oil improved excretion (OR 0.17 of incomplete CCE transit, 95% CI 0.09–0.32), and routine prokinetics improved CR compared with no use (OR 1.86, 95% CI 1.13–3.05). Low-fiber diets provided better cleansing than clear liquids (ACR 78.5% vs 70.0%). Conclusion: Current CCE bowel preparation regimens demonstrate variable performance relative to targets, with no single intervention demonstrating unequivocal superiority over others in pairwise comparisons. Evidence supports optimizing performance via low-volume PEG, NaP or Gastrografin-based boosters, routine prokinetics, and a low-fiber diet. A universal regimen is unlikely to suit all patients, highlighting the need for personalized protocols. Standardized cleansing scores and AI-assisted assessment are critical to improving reproducibility and cost-effectiveness.