Detection of Polyps During Colonoscopy Not Influenced by Timing when Procedure Performed in Half-day Blocks

Friday, October 29, 2010

SCOTTSDALE, Ariz. — A new study by Mayo Clinic in Arizona finds there is no difference in detection of polyps during a colonoscopy performed in the morning versus the afternoon under certain conditions — a finding in contrast to similar studies performed at other health care facilities that indicate sharp differences depending on the time of day.

The Mayo study found that when colonoscopies (endoscopic screening examinations of the colon and rectum) are performed in half-day blocks by different physicians, there is no difference in the adenoma detection rate (ADR), or detection of benign tumors, from morning to afternoon. Earlier studies elsewhere suggested that morning colonoscopies resulted in catching more polyps, and that as the day wore on, detection rates dipped. The difference was attributed to possible physician fatigue, making them less vigilant in the detection of polyps.

Even benign polyps have the potential to become cancerous, and are typically removed when detected during the colonoscopy.

The Mayo study, led by Suryakanth Gurudu, M.D, Gastroenterology, and colleagues at Mayo Clinic, concludes that timing of the colonoscopy is not an independent predictor of detection of polyps, and that by working in half-day blocks, with different physicians performing the procedures (from 8 a.m. until noon and again from 1 p.m. until 5 p.m.), the rate of detection of polyps is essentially the same.

In the study, a total of 5,727 colonoscopies were performed at Mayo Clinic in 2009. Of those, 4,665 were included in the study. Excluded from the study were patients who had incomplete data, poor bowel cleansing preparation and/or who had colonoscopy for evaluation of inflammatory bowel disease, bleeding or anemia.

Study participants in both the morning and afternoon procedures were of similar age, gender and body mass index so that possible existing physical conditions would not skew the data to suggest a higher — or lower — rate of detection.

"The quality of colonoscopy should be the same, no matter what time of day it is performed," said Dr. Gurudu. "Physicians and health care facilities have a responsibility to implement changes to assure consistently high quality exams with a high rate of polyp detection."

Missing or overlooking polyps during the screening process is sometimes blamed for patients developing colon cancer even after colonoscopy screening. "This reinforces the need for vigilance in screening for polyps, and for addressing the concept of work shifts that are optimal for watchful endoscopic screening by physicians," noted Dr. Gurudu.

According to the National Cancer Institute, because most colorectal cancers (90 percent) develop in people age 50 and older, the recommended screening colonoscopy should begin at age 50. Depending on family history and/or existing bowel conditions, a colonoscopy should be performed every five to 10 years.

Results of the study were presented at the American College of Gastroenterology Annual Scientific Meeting in San Antonio Oct. 15-20.

Co-authors of the study include Mayo Clinic physicians Shiva Ratuapli, M.D.; Jonathan Leighton, M.D.; Russell Heigh, M.D. and Michael Crowell, Ph.D.

To request an appointment at Mayo Clinic, please call 480-422-1490 for the Arizona campus, 904-494-6484 for the Florida campus, or 507-216-4573 for the Minnesota campus.

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