Introduction The British Society of Gastroenterology (BSG) guideline on the management iron deficiency anaemia advocates the use of unprepared CT scans for patients who are elderly frail or have significant co-morbidity (in those not suitable for endoscopy). The guideline does state that unprepared CT may miss cancerous lesions. Despite this, CT scanning is regularly used as a diagnostic modality for gastrointestinal (GI) cancer.

We have data of CT reports of patients with endoscopically diagnosed upper GI (UGI) and lower GI (LGI) cancers from 2014–2015 in Kettering General Hospital (KGH). We are auditing the proportion of GI cancers not detectable on CT scans.

Methods Data was analysed between January 1^st 2014 to December 31^st 2015 from endoscopy and radiology reporting systems to see what proportion of cancers were not detectable on CT scans. This covers two cohorts, patients (with GI cancers) with unprepared CT (days after index endoscopy) and patients that had their CT immediately post endoscopy (same-day – hence fasted pre-endoscopy for UGI endoscopy and prepared colons for LGI endoscopy).

Results Values represent cancers not detectable on CT scans.

Unprepared CT: LGI cancers 2 out of 78 (2.56%), UGI cancers 2 out of 29 (6.90%)

Prepared CT: LGI cancers 7 out of 68 (10.29%), UGI cancers 0 out of 25

All CTs: LGI cancers 9 out of 146 (6.16%, 95% CI 3.23–11.15%)

UGI cancers 2 out of 54 (3.70%, 95% CI 1.02–12.54%)

All cancers 11 out of 200 (5.50%, 95% CI 3.10–9.58%)

Conclusion Our audit shows that whilst CT scanning picks up the vast majority of endoscopically detected GI cancers, 6.16% of LGI and 3.70% of UGI cancers are not detected on CT. This rate isn’t improved in the prepared CT cohort (having CT immediately post endoscopy). Overall, 11 out of 200 cancers were not detected on CT (5.50% 95% CI 3.10–9.58%). Clinicians need to bear this in mind when using CT scanning to diagnose/rule out GI cancers.

Reference 1 Goddard AF, James MW, McIntyre, AS, Scott BB, on behalf of the British Society of Gastroenterology. Guidelines for the management of iron deficiency Anaemia. Gut 2011;60:1309-1316. doi:10.1136/gut.2010.228874

Disclosure of Interest None Declared