Different Bowel Preparation Schedule Leads to Different Diagnostic Yield of Proximal and Nonpolypoid Colorectal Neoplasm at Screening Colonoscopy in Average-Risk Population

Abstract

Accumulating evidence indicates that the timing of bowel preparation is crucial, but its impact on the diagnostic yield of proximal or nonpolypoid colorectal neoplasm remains unclear. This study aimed to investigate the impact of the timing of bowel preparation on the adenoma detection rate for nonpolypoid colorectal neoplasm at colonoscopy. This study is a retrospective analysis of a screening colonoscopy cohort database. The investigation was conducted at a screening colonoscopy unit in an university hospital. A consecutive series of 3079 subjects who received primary screening colonoscopy with different timing of bowel preparation was analyzed. Different timing of bowel preparation (same day vs prior day) was studied. The main outcomes measured were patient demographics, timing of bowel preparation, colon-cleansing levels, diagnostic yields of colonoscopy, including adenoma, advanced adenoma, and nonpolypoid colorectal neoplasm. There were a total of 1552 subjects in the morning group and 1527 in the evening group. More subjects had proximal adenoma (175, 11.3% vs 138, 9.0%, P = .04), advanced adenoma (68, 4.4% vs 46, 13.0%, P = .044), nonpolypoid colorectal neoplasm (98, 6.3% vs 67, 4.4%, P = .018), proximal nonpolypoid colorectal neoplasm (71, 4.6% vs 40, 2.6%, P = .004), and advanced nonpolypoid colorectal neoplasm (25, 1.6% vs 12, 0.8%, P = .036) detected by same-day preparation. On multivariate regression analysis, the adenoma detection rate was significantly higher in the same-day group regarding overall and proximal adenoma (OR 1.23, 95% CI: 1.00-1.50; OR 1.35, 95% CI: 1.05-1.74), advanced adenoma (OR 1.53, 95% CI: 1.04-2.28), overall, proximal, and advanced nonpolypoid colorectal neoplasm (OR 1.48, 95% CI: 1.06-2.08; OR 1.82, 95% CI: 1.20-2.75; OR 1.96, 95% CI: 1.12-3.37). The adenoma detection rate was also significantly different among endoscopists. This was a single-center, nonrandomized trial. Improving bowel preparation quality by same-day preparation may lead to enhanced detection of overall, proximal, and advanced nonpolypoid colorectal neoplasm.