Low rate of large polyps (>9 mm) within 10 years after an adequate baseline colonoscopy with no polyps

Guidelines recommend a 10-year interval between screening colonoscopies with negative results for average-risk individuals. However, many patients are examined at shorter intervals. We investigated outcomes of individuals with no polyps who had repeat colonoscopy in <10 years.

Data were collected using the National Endoscopic Database, from 69 gastroenterology centers, on 264,184 asymptomatic subjects who underwent screening colonoscopies from 2000 through 2006, were found to have no polyps, and received another colonoscopy examination within <10 years.

No polyps were found in 147,375 patients during a baseline colonoscopy; 17,525 patients (11.9%) had a follow-up colonoscopy within <10 years, including 1806 (10.3%) who received the follow-up colonoscopy within <1 year. The most common reason for repeating the examination within 1 year was that the first was compromised by inadequate bowel preparation or incomplete examination. Of these patients, 6.5% (95% confidence interval: 5.3-7.6) had large polyp(s) >9 mm-a proportion similar to the prevalence in the average-risk screening population. Reasons that examinations were repeated within 1-5 years included average-risk screening (15.7%), family history of colon polyps or cancer (30.1%), bleeding (31.2%), gastrointestinal symptoms (11.8%), or a positive result from a fecal blood test (5.5%). If the baseline examination was adequate, the incidence of large polyps within 1-5 years after baseline colonoscopy was 3.1% (95% confidence interval: 2.7-3.5) and within years 5-10 years was 3.7% (95% confidence interval: 3.3-4.1).

Repeat colonoscopies within 10 years are of little benefit to patients who had adequate examinations and were found to have no polyps. Repeat colonoscopies are beneficial to patients when the baseline examination was compromised.