Impact of Bowel Preparation Quality on Adenoma Identification During Colonoscopy and Optimal Timing of Surveillance

All present guidelines regarding surveillance intervals after index colonoscopy are based on optimal bowel preparation. However, the appropriate timing of repeat colonoscopy after suboptimal bowel preparation is not clear.

To determine the appropriate timing of repeat colonoscopy following index colonoscopy with suboptimal bowel preparation.

The medical records of patients who underwent colonoscopy over 5 years were retrospectively analyzed. Index colonoscopy was defined as the first colonoscopy in patients who underwent the procedure at least twice during the study period. Bowel preparation quality was classified as optimal, fair, or poor.

The overall adenoma detection rate was 39.1% (95% confidence interval [CI], 38.0-40.1%), but the detection rate depended significantly on bowel preparation quality (p < 0.001). The adenoma miss rate (AMR) was significant after poor (69.6%) than after optimal (27.3%) and fair (48.1%) preparation (p < 0.001). At surveillance intervals ≤2 years, the odds ratio (OR) for AMR was significantly higher for poor (OR 6.25; 95% CI, 3.76-11.83) and fair (OR 3.67; 95% CI, 2.19-6.16) preparation relative to optimal preparation; however, no difference was observed at surveillance intervals >2 years.

Bowel preparation quality significantly affects AMR. Colonoscopy should be repeated within 2 years in patients with suboptimal bowel preparation at index colonoscopy.