Early Morning Colonoscopies Detect More Polyps

Posted on November 11th, 2009 by

Among patients undergoing colonoscopy at a Veteran’s Administration (VA) medical center, a greater number of polyps was detected among patients seen early in the morning than among patients seen later in the day. The reasons for this are uncertain, but it’s possible that the lower rate of polyp detection later in the day is the result of provider fatigue or less complete bowel preparation. These results were published in Clinical Gastroenterology and Hepatology.

Colon cancer is the second leading cause of cancer death in the United States. If detected and treated early, colorectal cancer is highly curable. Screening for colorectal cancer is recommended starting at the age of 50 for individuals at average risk of developing the disease and earlier for those at higher risk. Several screening tests are available, including the fecal occult blood test (FOBT), sigmoidoscopy, double-contrast barium enema, and colonoscopy.

During a colonoscopy, a lighted tube with an attached camera is inserted into the rectum and through the colon. The physician views the colon on a screen and is able to biopsy abnormal areas and remove polyps. Because many colorectal cancers begin as polyps, removal of polyps may prevent the development of colorectal cancer or allow for the earlier detection of colorectal cancer.

To explore whether polyp detection varies by time of day, researchers evaluated the medical records of 477 patients who received colonoscopies at the VA medical center unit affiliated with the University of California at Los Angeles.

Early colonoscopies were defined as those that occurred at or before 8:30 am.

  • 20% more polyps per patient were detected among patients who received colonoscopies early in the day than among patients who received colonoscopies later in the day.
  • The number of polyps detected decreased hour by hour as the day progressed.

The reasons for the differences in polyp detection by time of day are uncertain, but the researchers speculate that provider fatigue later in the day may be one contributing factor. It’s also possible that better bowel preparation the night before contributes to more complete polyp detection among patients seen in the morning.

Reference: Chan MY, Cohen H, Spiegel BMR. Fewer polyps detected by colonoscopy as the day progresses as a Veteran’s Administration teaching hospital. Clinical Gastroenterology and Hepatology. 2009;7:1217-1223.

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