434 Incidence of Normal Colonoscopy in Faecal Immunochemical Test (FIT) Positive Patients in The Colorectal 2-Week-Wait (2WW) Pathway at A District General Hospital (DGH)

FIT is a quantitative, highly specific test to detect blood in stool for malignant and non-malignant colorectal diagnoses. Incidence of normal colonoscopy following positive FIT is not widely reported. We conducted a retrospective audit to analyse this patient cohort to evaluate diagnostic accuracy and reporting standards of colonoscopy. Method FIT-positive was defined as > 10µgHb/g faeces. Using FIT value, patients were separated into Groups 1, 2 and 3: 10-99, 100-200 and >200µgHb/g faeces respectively. Normal colonoscopy was defined as no neoplastic or benign findings reported. Patients referred in the 2WW-pathway after introduction of FIT-testing in October 2019 to the onset of COVID-19 pandemic in March 2020 were included. Data on age, gender, comorbidities and additional investigations were collected. Results There were 1072 referrals in the study period; 405 had FIT done, 265 were FIT-positive and had colonoscopy referral. Four patients were excluded after further investigations showed diverticulosis and gastritis. FIT-stratified normal-colonoscopy rate was 13.3% (28/210) overall, and 14.1% (23/163), 16.7% (2/12) and 8.6% (3/35) for Group 1, 2 and 3 respectively. Conclusions Our study was limited by the onset of COVID-19 pandemic. In the short study period, 13.3% FIT-positive patients had normal colonoscopy. There are no comparative data in literature for this parameter. Higher FIT-values were associated with lower normal colonoscopy incidence. It is possible that some endoscopists failed to record positive, non-clinically significant findings. We are currently studying larger patient cohorts and in parallel, looking at Bowel Cancer Screening Programme (BCSP) patients.