Diagnostic consequence of colonoscopy repeated within 3 years at a tertiary hospital: a single-centre observational study.

[BACKGROUND] In Australia, the number of colonoscopies performed each year is increasing, placing stress on the resources of the health system.

[AIM] Our aim is to assess the diagnostic yield of repeat colonoscopies performed within 3 years of a prior colonoscopy and adherence to the National Health and Medical Research Council (NHMRC) surveillance colonoscopy guidelines.

[METHODS] We performed a retrospective analysis of colonoscopies performed in 2021, repeated within 3 years of the previous colonoscopy at a tertiary hospital in Western Australia. We extracted data from index and repeat colonoscopies regarding patient demographics, referrer, indications, histopathology, colonoscopy findings, proceduralist specialty and recommendations. We sought associations between indications and diagnostic yield and adherence to NHMRC surveillance guidelines.

[RESULTS] Out of the 5838 total colonoscopies performed, 951 (16.3%) were repeats within 3 years. For polyp surveillance, 56.2% were adherent to the guidelines. Colonoscopies performed for poor bowel preparation or colorectal cancer syndromes mostly occurred within the recommended time frame (>80%). Considering all repeat colonoscopy indications, high-risk conventional adenomas were detected in 84 (8.8%), advanced sessile serrated lesions (SSLs) in three (0.32%) but no cancer was identified.

[CONCLUSIONS] Adherence to NHMRC surveillance colonoscopy guidelines after polypectomy is inadequate, with almost half of colonoscopies being performed outside of the recommended surveillance interval. The diagnostic yield for advanced adenomas, SSLs or colorectal cancer from repeat colonoscopies within 3 years of the previous one for all indications was low. Therefore, we recommend increased scrutiny of the appropriateness of repeat colonoscopy referrals within 3 years of the previous one.