Prevalence and variable detection of proximal colon serrated polyps during screening colonoscopy

Background & aims: Colonoscopy may have a greater protective effect for distal colorectal cancer (CRC) than proximal CRC. Serrated polyps are frequently located in the proximal colon, can be missed during colonoscopy, and may progress to CRC. We investigated the prevalence and endoscopist detection rates of proximal serrated polyps in a large cohort of average risk patients undergoing screening colonoscopy.

Methods: Screening colonoscopies performed by 15 attending gastroenterologists at 2 academic endoscopy units between 2000 and 2009 were reviewed. Serrated polyps included hyperplastic polyps, sessile serrated adenomas, and traditional serrated adenomas. Endoscopist-level detection rates for adenomas and serrated polyps were calculated. Pearson correlation coefficients were calculated to evaluate the associations of adenoma and proximal serrated polyp detection rates. Logistic regression was used to compare endoscopists' detection rates.

Results: A total of 11,049 polyps were detected in 6681 colonoscopies (adenomas: 5637, 51%; serrated: 3984, 36%; proximal serrated: 1238, 11%). The proportion of colonoscopies with at least one proximal serrated polyp was 13% (range 1%-18%). Proximal serrated polyp detection rates per colonoscopy ranged from 0.01 to 0.26. Adenoma and proximal serrated polyp detection rates per colonoscopy were strongly correlated (R = 0.76, P = .0005). The odds of detecting at least one proximal serrated polyp for individual endoscopists ranged from 0.05 to 0.67 compared to the highest level detector. Endoscopist (P < .0001), but not patient age (P = .76) or gender (P = .95), was associated with proximal serrated polyp detection.

Conclusions: In an average-risk screening cohort, the detection of proximal serrated polyps was highly variable and endoscopist dependent. A significant proportion of proximal serrated polyps may be missed during colonoscopy. High-quality colonoscopy is important for the detection and resection of all polyps with neoplastic potential.