Colonoscopy Withdrawal Times Linked to Polyp Detection Rates

Article ID: 612629

Released: 21-Jan-2014 12:00 PM EST

Source Newsroom: Norris Cotton Cancer Center Dartmouth-Hitchcock Medical Center

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  • Credit: Tom McNeill

Newswise — (Lebanon, NH, 1/21/14) — Dartmouth-Hitchcock Norris Cotton Cancer Center (NCCC) researchers found that longer withdrawal times during a colonoscopy correlates with a higher rate of polyp detection. The study was recently published online in in the American Journal of Gastroenterology.

“There has been controversy over whether longer withdrawal times could lead to detection of increased numbers of polyps of various types,” said Lynn F. Butterly, MD, director of Colorectal Cancer Screening at Dartmouth-Hitchcock Medical Center and NCCC, and associate professor of Medicine at the Geisel School of Medicine at Dartmouth. “Since the rate of discovery of polyps is a critical quality measure for colonoscopy, examining whether or not there is an association between withdrawal time and finding more polyps may contribute evidence leading to improved quality in screening through colonoscopy.”

During a colonoscopy, a lighted tube (colonoscope) is passed through the colon to find and remove polyps. The colonoscope is passed to the area where the large and small intestine meet, and the scope is then slowly withdrawn back through the colon, carefully examining the lining. The time spent in withdrawing the scope and doing a detailed examination is called the withdrawal time.

Colorectal cancer (CRC) is the second most common cause of death from cancer in the US, but CRC is preventable through screening. Most CRC begins as a small growth on the lining of the colon, known as a polyp. Over a period of several years, some polyps may turn into cancer.

Using data from the New Hampshire Colonoscopy Registry (NHCR), the authors examined how endoscopists’ withdrawal time in normal, well-prepped colonoscopies affected their polyp detection rates. They 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. Polyp detection rates were calculated based on median withdrawal time in normal exams.

“Our investigation demonstrates a statistically significant correlation between longer normal withdrawal time and higher (overall) polyp detection rates, adenoma detection rates, and serrated polyp detection rates, and provides strong evidence to support a 9-minute median normal withdrawal time as a quality standard,” Butterly said.

This investigation was done through the New Hampshire Colonoscopy Registry (NHCR), which is a project supported by grants # R21CA100553 and R01CA131141 from the National Cancer Institute.

About Norris Cotton Cancer Center at Dartmouth-HitchcockNorris Cotton Cancer Center combines advanced cancer research at Dartmouth College and the Geisel School of Medicine at Dartmouth with patient-centered cancer care provided at Dartmouth-Hitchcock Medical Center, at Dartmouth-Hitchcock regional locations in Manchester, Nashua, and Keene, NH, and St. Johnsbury, VT, and at 12 partner hospitals throughout New Hampshire and Vermont. It is one of 41 centers nationwide to earn the National Cancer Institute’s “Comprehensive Cancer Center” designation. Learn more about Norris Cotton Cancer Center research, programs, and clinical trials online at


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