Publication:

Colonoscopic miss rate for colorectal cancer: a district general hospital experience

Background The aim of the study was to review our post-colonoscopy colorectal cancer (PCCRC) diagnoses rate and compare it to national standards, to identify any common factors in our missed cancer cases and create a policy for capturing missed cancers data.

Methods We analyzed retrospectively collected data on patients with colorectal cancer from January 2015 to July 2017. Patients who had a previous colonoscopy within 3 years of diagnosis were then identified. We excluded colonoscopies done within 6 weeks of diagnosis or repeat colonoscopies due to poor bowel preparation.

Results 503 colorectal cancer patients were identified. 135 (26.8%) were initially diagnosed without a lower GI endoscopy. 30 had a negative colonoscopy 6 weeks to 3 years prior to diagnosis. Only 10 patients (2.7%) were true missed lesions (false negative colonoscopy). Male/female: 5/5. Mean age was 68.4 (49-80). 9 patients had good or satisfactory bowel preparation. 50% of lesions were found during follow-up or treatment of a different lesion. Average time from false negative scope to diagnosis was 20.3 months (4-31). Sites of missed lesions are left colon- 4, low rectum- 3, caecum- 2 and transverse colon- 1.

Conclusions Our PCCRC rate is below the GUT recommended target of <5% and well below the national average 8.5%. We identified no common features across all missed cases. Contrary to other published data, right sided lesions were less common with no female predominance. We recognize the limitations of access to only local trust data. We propose to monitor PCCRC rate annually, present this at clinical governance meetings and review each case individually as an adverse event.