In many regions, the demand for colonoscopy exceeds its availability. Patients undergoing repeat examinations comprise a significant proportion of those on waiting lists.

To assess the yield of repeat colonoscopy in varied clinical settings.

Cohort study.

Endoscopic database of an Australian tertiary referral hospital.

Adults who had ≥2 colonoscopies between 1992 and 2004. Patients were excluded if the repeat procedure was for completion or for high-risk surveillance.

Yield for neoplasia by indication, interval to repeat examination, and appropriateness for surveillance (determined by National Australian guidelines).

A total of 4974 colonoscopies in 2075 patients were studied. The mean age was 63.1 years (range, 19.2-92.4 years). The mean number of examinations was 2.4 (range, 2-8), with a mean interval between examinations of 2.9 years. Colorectal cancer (CRC) was significantly more prevalent at initial colonoscopy compared with subsequent colonoscopies (7.9% vs 0.6%; prevalence ratio 14.2, 95% confidence interval [CI] 8.5-23.7, P < .001), as were advanced adenomas (15.3% vs 4.8%; prevalence ratio 3.2, 95% CI 2.6-3.9, P < .001). No CRCs were detected in symptomatic patients undergoing polyp surveillance examinations performed before the recommended interval.

Retrospective design.

Yield of repeat colonoscopy is significantly lower than for initial colonoscopy, irrespective of indication. In symptomatic patients within a polyp surveillance program, the yield is negligible when a colonoscopy is performed before the recommended surveillance interval. The need for a repeat colonoscopy should be carefully considered, and patients who have never had a colonoscopy must take priority on waiting lists over those awaiting repeat examinations.