Rescue bowel preparation: same day 2 L polyethylene glycol addition, not superior to bisacodyl addition 7 days later.
The optimal colon-cleansing method after failure of bowel preparation (BP) for colonoscopy has not been established. We aimed to compare BP rescue methods after failed initial BP and to identify risk factors for rescue BP failure. Eighty-five patients with BP failure after 4 L polyethylene glycol (PEG) ingestion were prospectively enrolled from March 2008 to March 2012. A second colonoscopy was performed either on the same day after ingestion of another 2 L PEG (group A) or 1 week later after ingestion of 4 L PEG plus 20 mg oral bisacodyl (group B). Differences between groups in terms of BP quality and risk factors for a poor BP on the second colonoscopy were investigated. Median patient age was 59 years, 45 were male (52.9 %), and 17 (20 %) had poor BP on the second colonoscopy. For group B, the multivariable-adjusted odds ratio (OR) for poor BP on the second colonoscopy relative to group A was 0.68 (95 % confidence interval [CI], 0.16-2.95). Adequately ingested PEG during the initial colonoscopy was associated with poor BP on the second colonoscopy (OR 4.05; 95 % CI 1.04-15.75). The two groups had similar patient discomfort rates during the second BP. The two groups did not differ in rescue BP failure rate. Initial BP failure after adequate consumption of 4 L PEG may be a risk factor for rescue BP failure. A stricter BP regimen should be considered for these patients.