Guidelines recommend a 10-year interval between screening colonoscopies with negative results for average-risk individuals.
However, many patients are examined at shorter intervals.
Dr David Lieberman and colleagues from Oregon, USA 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.
The team evaluated 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.
|The incidence of large polyps within 5–10 years after baseline colonoscopy was 4%|
The team noted that 12% of patients had a follow-up colonoscopy within <10 years, including 10% who received the follow-up colonoscopy within <1 year.
The research team found that the most common reason for repeating the examination within 1 year was that the first was compromized by inadequate bowel preparation or incomplete examination.
Of these patients, 7% had large polyps >9 mm—a proportion similar to the prevalence in the average-risk screening population.
The team found that reasons that examinations were repeated within 1–5 years included average-risk screening, family history of colon polyps or cancer, bleeding, gastrointestinal symptoms, or a positive result from a fecal blood test.
If the baseline examination was adequate, the incidence of large polyps within 1–5 years after baseline colonoscopy was 3%, and within years 5–10 years was 4%.
Dr Lieberman's team concludes, "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 compromized."