Serrated and adenomatous polyp detection increases with longer withdrawal time: results from the New Hampshire Colonoscopy Registry

Am J Gastroenterol. 2014 Mar;109(3):417-26. doi: 10.1038/ajg.2013.442. Epub 2014 Jan 7.


Objectives: Detection and removal of adenomas and clinically significant serrated polyps (CSSPs) is critical to the effectiveness of colonoscopy in preventing colorectal cancer. Although longer withdrawal time has been found to increase polyp detection, this association and the use of withdrawal time as a quality indicator remains controversial. Few studies have reported on withdrawal time and serrated polyp detection. Using data from the New Hampshire Colonoscopy Registry, we examined how an endoscopist's withdrawal time in normal colonoscopies affects adenoma and serrated polyp detection.

Methods: We analyzed 7,996 colonoscopies performed in 7,972 patients between 2009 and 2011 by 42 endoscopists at 14 hospitals, ambulatory surgery centers, and community practices. CSSPs were defined as sessile serrated polyps and hyperplastic polyps proximal to the sigmoid. Adenoma and CSSP detection rates were calculated based on median endoscopist withdrawal time in normal exams. Regression models were used to estimate the association of increased normal withdrawal time and polyp, adenoma, and CSSP detection.

Results: Polyp and adenoma detection rates were highest among endoscopists with 9 min median normal withdrawal time, and detection of CSSPs reached its highest levels at 8-9 min. Incident rate ratios for adenoma and CSSP detection increased with each minute of normal withdrawal time above 6 min, with maximum benefit at 9 min for adenomas (1.50, 95% confidence interval (CI) (1.21, 1.85)) and CSSPs (1.77, 95% CI (1.15, 2.72)). When modeling was used to set the minimum withdrawal time at 9 min, we predicted that adenomas and CSSPs would be detected in 302 (3.8%) and 191 (2.4%) more patients. The increase in detection was most striking for the CSSPs, with nearly a 30% relative increase.

Conclusions: A withdrawal time of 9 min resulted in a statistically significant increase in adenoma and serrated polyp detection. Colonoscopy quality may improve with a median normal withdrawal time benchmark of 9 min.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenomatous Polyps / diagnosis*
  • Aged
  • Colonic Polyps / diagnosis*
  • Colonoscopy / methods*
  • Colorectal Neoplasms / diagnosis*
  • Female
  • Humans
  • Male
  • Middle Aged
  • New Hampshire
  • Registries
  • Regression Analysis
  • Time Factors