THURSDAY, Nov. 12 (HealthDay News) -- The number of polyps detected by colonoscopy declines as the day progresses, indicating that those conducting endoscopies may be at their most adept at the start of the day, according to a study in the November issue of Clinical Gastroenterology and Hepatology.

Michael Y. Chan, M.D., of the David Geffen School of Medicine at the University of California in Los Angeles, and colleagues conducted a study of 477 patients who underwent colonoscopy and compared the polyp yield of procedures done early in the morning to those done later in the day.

There was a 27 percent higher polyp count for patients who underwent colonoscopy earlier in the day compared to those who had the procedure later, and as each hour went by, the count of hyperplastic and adenomatous polyps went down, the researchers found. When the data was subjected to multivariable analysis, the investigators concluded that cases handled early in the morning had a 20 percent higher polyp yield per patient than those done later in the day.

"This effect was more than a morning versus afternoon phenomenon -- it was an hour-by-hour effect as the day progressed," the authors write. "The effect of procedure start time was independent of a wide range of key variables, including demographics, bowel preparation quality, cecal intubation and trainee participation."

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