The effect of colonoscopy preparation quality on adenoma detection rates.
Colonoscopy reduces the risk of colorectal cancer mortality by removing precancerous adenomas. The detection rate of subcentimeter (<10 mm) polyps is lower for procedures with inadequate preparation quality. To compare the adenoma detection rates of small (6-9 mm) and diminutive (≤ 5 mm) adenomas in patients with poor and fair quality preparations with those with adequate quality preparations. Cross-sectional study and multivariable, hierarchical model. Roudebush Veterans Affairs Medical Center. This study involved 8800 colonoscopies performed from 2001 to 2010. Preparation quality rating, polyp size, and polyp histology. Preparation quality was rated as fair in 2809 (31.9%) and poor in 829 (9.4%) colonoscopies. In patients with poor compared with adequate quality, the detection rate was lower for diminutive adenomas (odds ratio [OR] 0.57; 95% CI, 0.47-0.70) but not for small adenomas (OR 0.84; 95% CI, 0.65-1.07). There were no differences in the detection rate of diminutive (OR 1.08; 95% CI, 0.94-1.24]) or small (OR 1.09; 95% CI, 0.94-1.27) adenomas in patients with fair compared with adequate quality preparation. Detection of advanced histology in patients with poor preparation quality was lower than in those with adequate quality (P = .027; 3.3% vs 5.0%), but there was no difference in those with fair compared with adequate quality (P = .893; 4.9% vs 5.0%). Single-center study; no standardization of preparation quality or size measurements. A fair preparation quality rating does not decrease the detection rate for adenomas of any size or for advanced histology, suggesting that fair quality may be considered adequate and that follow-up intervals may not need to be shortened. Poor preparation quality decreases the detection rate of diminutive adenomas and advanced histology, suggesting substandard colonoscopy performance.