Researchers claim doctors often can’t see potentially dangerous precancerous lesions when patients don’t sufficiently prep for colonoscopy by cleansing their colons.
Doctors often missed at least 1 precancerous growth in about one-third of patients who did not properly prepare for their colonoscopy, according to researchers from Washington University School of Medicine in St. Louis. The report, published recently in Gastrointestinal Endoscopy, states that the discovery of those polyps occurred months later when patients had their next colonoscopy.
Several studies have found that up to 25% of colonoscopy patients don’t prepare well for the test, but this is the first study to point out the possible consequences of poor colon preparation in average-risk outpatients.
Because of the study findings, researchers believe the colonoscopy should be discontinued and rescheduled if inadequate bowel prep results in poor viewing of the colon.
“We often can detect preparation problems during the first few minutes of the procedure,” says first author Reena Chokshi, MD, a gastroenterology fellow at Washington University. “And based on this study, we would say that rather than subjecting a patient to the potential risks of a full colonoscopy when we may not be able to detect polyps, or other precancerous growths called adenomas, it may be better to bring that patient back as soon as possible for a repeat procedure with better bowel preparation.”
The researchers retrospectively studied patients with an average risk of colon cancer. Those with a history of inflammatory bowel disease, a family history of colorectal cancer, or a medical history of colon polyps were not included in the study.
Between 2004 and 2009, 373 patients who received screening colonoscopies at the outpatient endoscopy center were identified as having inadequate bowel preparation. During the study period, a second colonoscopy was performed on 133 of those patients, and 33.8% of them had at least 1 precancerous adenoma detected in that repeat screening. Furthermore, almost 1 in 5 of that group were considered to be at high risk for colon cancer because they had more than 3 adenomas detected, or the test discovered at least 1 large lesion.
Researchers also discovered that 18% of the patients who had a second colonoscopy would have been given different recommendations if their polyps and adenomas had been detected during the initial screening. These recommendations may have included more frequent colonoscopies to monitor the development of growths in the colon.
“It generally takes several years for an adenoma to become cancerous,” Chokshi says. “But it’s hard to know where in that sequence a particular adenoma is when we detect it. So it certainly is possible that any lesion we miss during a colonoscopy could develop into a malignancy before a person’s next colonoscopy, especially if it doesn’t happen until 10 years later.”
Source: Washington University in St. Louis.
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