Variation in the Detection of Serrated Polyps in an Average Risk Colorectal Cancer Screening Cohort

OBJECTIVES: Serrated polyps are precursors in an alternative pathway to colon cancer. These polyps are frequently sessile or flat, located in the proximal colon, and may be overlooked during colonoscopy. Histological criteria to classify these polyps have only recently been described. This study assessed the variation of serrated polyp detection among endoscopists and pathologists in an average risk-screening cohort and trends in detection over time. METHODS: Endoscopy and pathology reports were reviewed from all average risk-screening colonoscopies at an urban academic medical center from 2006 through 2008. Polyps were classified as adenoma (tubular, tubulovillous, or villous), serrated polyp (hyperplastic polyp (HP), sessile serrated adenoma (SSA), or dysplastic serrated polyp (DSP)), adenocarcinoma, or other. Differences in polyp detection among endoscopists and pathologists were tested with χ(2)-tests. Potential predictors of polyp detection were modeled with Poisson regression. RESULTS: Included in the study were 4,335 polyps from 7,192 colonoscopies. Detection prevalence (patients with at least one polyp per 100 colonoscopies) was 22.2 for adenomas, 11.7 for HP, 0.6 for SSA, and 0.2 for DSP. Detection prevalence of proximal SSAs increased from 0.2 in 2006 to 4.4 in 2008 (P<0.001). Detection prevalences among endoscopists differed significantly for adenomas, HP, and SSA. Classification rates among pathologists differed significantly for HP and SSA, but not for adenoma or DSP. On multivariate analysis, endoscopist was a significant predictor of adenoma, HP, and SSA. Pathologist was a significant predictor of HP, SSA, and DSP, but not adenoma. CONCLUSIONS: This study describes the detection of colorectal polyps in an average risk-screening cohort at an urban academic medical center. Detection of proximal SSAs increased during the study period. Detection of adenoma, HP, and SSA differed significantly by endoscopist. Classification of HP and SSA differed significantly by pathologist. Endoscopy and pathology practices should consider educational interventions to improve serrated polyp detection and standardize classification.