According to the results of a study published in the New England Journal of Medicine, physicians who withdraw the colonoscope more quickly during routine screening colonoscopy detect fewer colorectal polyps than physicians who withdraw the colonoscope more slowly.
Colorectal cancer is the second leading cause of cancer-related deaths in the U.S. The disease develops in the colon (the longest part of the large intestine) or the rectum (the last several inches of the large intestine). It may start as a precancerous growth known as an adenomatous polyp or adenoma.
Screening tests for colorectal cancer include fecal occult blood test (FOBT), sigmoidoscopy, colonoscopy, barium enema, and digital rectal exam.
Colonoscopy is a procedure in which a lighted tube is inserted through the rectum and advanced through the entire large intestine. The physician performing the procedure is able to view the colon on a screen. If any abnormal areas are detected, the physician is able to remove these areas during the colonoscopy. A colonoscopy requires light sedation and a bowel cleansing prior to the procedure.
The frequency with which adenomas are detected during colonoscopy has been reported to vary across physicians. Some of this variability may be due to how physicians perform the exam.
Because many colorectal adenomas are detected during the withdrawal of the colonoscope, the speed with which the colonoscope is withdrawn may influence adenoma detection. Current expert opinion suggests that physicians should take at least six minutes to withdraw the colonoscope.
To evaluate whether the speed with which the colonoscope is withdrawn influences the number of adenomas detected, researchers conducted a study among 12 physicians in a large community-based gastroenterology practice.
During the study period (January 2003 to March 2004), these physicians performed 2,053 screening colonoscopies in individuals who had not previously undergone colonoscopy.
- Abnormal growths (mostly adenomatous polyps) were detected in 24% of screened individuals.
- The average number of adenomas detected per subject ranged from 0.10 to 1.05 (a ten-fold difference) across physicians.
- The percent of patients with identified adenomas ranged from 9.4% to 32.7% across physicians.
- Physicians with average withdrawal times of six minutes or longer had a higher rate of adenoma detection than physicians with average withdrawal times less than six minutes. Physicians with longer withdrawal times detected abnormal growths in 28.3% of patients, and physicians with shorter withdrawal times detected abnormal growths in 11.8% of patients.
The researchers conclude that slower withdrawal of the colonoscope may improve the detection of colorectal polyps during screening colonoscopy. The researchers note that this is a preliminary study, and that additional studies of this question are warranted.
Reference: Barclay RL, Vicari JJ, Doughty AS, Johanson JF, Greenlaw RL. Colonoscopic Withdrawal Times and Adenoma Detection during Screening Colonoscopy. New EnglandJournal of Medicine. 2006;355:2533-41.
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