The Effect of the Bowel Preparation Status on the Risk of Missing Polyp and Adenoma during Screening Colonoscopy: A Tandem Colonoscopic Study

BACKGROUND/AIMS Although a small amount of fecal material can obscure significant colorectal lesions, it has not been well documented whether bowel preparation status affects the missing risk of colorectal polyps and adenomas during a colonoscopy. METHODS We prospectively enrolled patients with one to nine colorectal polyps and at least one adenoma of >5 mm in size at the screening colonoscopy. Tandem colonoscopy with polypectomy was carried out within 3 months. RESULTS A total of 277 patients with 942 polyps and 714 adenomas completed index and tandem examinations. At the index colonoscopy, 187 polyps (19.9%) and 127 adenomas (17.8%) were missed. The per-patient miss rate of polyps and adenomas increased significantly as the bowel cleansing rate declined from excellent to poor/inadequate on the Aronchick scale (polyps, p=0.024; adenomas, p=0.040). The patients with poor/inadequate bowel preparation were independently associated with an increased risk of having missed polyps (odds ratio [OR], 3.21; 95% confidence interval [CI], 1.13 to 9.15) or missed adenomas (OR, 3.04; 95% CI, 1.04 to 8.88) compared to the patients with excellent bowel preparation. CONCLUSIONS The risk of missing polyps and adenomas during screening colonoscopy is significantly affected by bowel preparation status. It seems appropriate to shorten the colonoscopy follow-up interval for patients with suboptimal bowel preparation.