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P294 Microscopic colitis: a missed opportunity to diagnose during colonoscopy

S. A. Raju*1, M. Kurien1, T. S. Chew1, K. Chapple2, D. S. Sanders1

1Academic Unit of Gastroenterology, Department of Infection, Immunity and Cardiovascular Disease, Sheffield, UK, 2Northern General Hospital, Sheffield, UK

Background

British Society of Gastroenterology (BSG) guidelines on chronic diarrhoea state biopsies should be taken from both the left and right colon to exclude microscopic colitis (MC). There is a paucity of work assessing biopsy adherence rates, and whether this is influencing detection of MC.

Methods

A UK study from 2 hospitals in South Yorkshire of retrospectively collected data between 2007 and 2017 of all patients referred for colonoscopy with chronic diarrhoea, IBS type symptoms or suspected inflammatory bowel disease (IBD). Data were analysed using IBM SPSS v25 to complete χ2 where required. Data were also collected on patients diagnosed with MC.

Results

A total of 10015 lower gastrointestinal endoscopies (84.3% colonoscopies and 15.7% flexible sigmoidoscopies) were performed (59.3% female, median age 57 years, IQR 43–69 years). Colonoscopies were performed for investigation of chronic diarrhoea, IBS-diarrhoea (IBS-D), IBS-mixed (IBS-M), or suspected IBD (22.4%, 59.0%, 14.6% and 3.9%). Cancer exclusion pathways accounted for 28.3% of patients. Endoscopies were performed by consultants, trainees, clinical nurse specialists (CNS), and others including GPs (34.3%, 31.6%, 30.4%, and 3.7%, respectively). In total, 19.5% of colonoscopies conformed to biopsy guidelines. In the other cases biopsies were taken from incorrect sites including: only left or right sides of the colon, the rectum and randomly (15.8%, 10.7%, 24.2%, and 58.7%, respectively). In 8.6% of colonoscopies, no biopsies were taken. There was a significant difference in the adherence to guidelines by consultants, trainees, CNS and others including GPs (11.6%, 17.8%, 29.2%, 18%, respectively, p < 0.005). CNS also adhered to guidelines significantly more often than gastroenterologists and general surgeons (29.2% vs. 19.1% and 6.8%, respectively, p < 0.005). Patients on cancer exclusion pathways were less likely to have biopsies as per guidelines (16.8% vs. 20.0%, p < 0.005). The highest adherence to guidelines (48%) occurred in a subgroup of IBD where the indication was to rule out MC. The adherence to biopsy guidelines differed for chronic diarrhoea, IBS-D, IBS-M, or IBD (17.1%, vs. 20.7%, 14.8%, 31.5%, respectively, p < 0.005). In the same study period, 402 patients had been diagnosed with MC of which 24.4% had at least 1 previous colonoscopy, which may be a missed opportunity to diagnose MC.

Conclusion

Biopsies are not currently taken in accordance with guidelines, which may cause delays or missed diagnoses of MC. This is likely to impact estimates of the prevalence of this disease. This study suggests the importance of classifying MC as a subtype of IBD to improve the adherence to guidelines in patients presenting with chronic diarrhoea or IBS type symptoms.