ISOLATED TERMINAL ILEITIS AT COLONOSCOPY – DOES ULCERATION PREDICT CROHN’S DISEASE?

Aims Faecal calprotectin (FC) is a biomarker that is elevated in active inflammatory bowel disease (IBD). Ileo-colonoscopy is usually performed to confirm a diagnosis of IBD, but isolated non-specific terminal ileitis is often inconclusive despite biopsy. We explored the the presence of macroscopic terminal ileum (TI) ulceration in predicting Crohn’s disease, over and above endoscopic terminal ileitis alone.

Methods Retrospective review at a London district general hospital. GI reporting tool software was used to identify all endoscopic cases of isolated terminal ileitis (i.e. normal colon) diagnosed over a 4 year period (January 2015 to December 2018). We used > 150 µg/g as a cut-off for elevated FC.

Results 139 cases of isolated terminal ileitis were identified. 65 cases were excluded as they were known Crohn’s disease. 74 cases were included for analysis (mean age 43.9, female 44 (59.5%). 38 (51.4%) had a faecal calprotectin performed of which 27 (71.1%) had a FC > 150. Median CRP 4 (range 0–220).

Histology demonstrated normal mucosa in 16 (21.6%), non-specific inflammation in 45 (60.8%), ulceration 9 (12.2%) and granulomas 1 (1.4%). Macroscopic terminal ileum ulcers were present in 60 (81.1%) but only 9 of these had histological evidence of ulceration (15%). A new diagnosis of Crohn’s disease was subsequently made in 15 patients (20.3%). Binary logistic regression showed an odds ratio of 1.28 (p = 0.016, CI 0.45–0.047) in the TI ulcers + FC > 150 group vs. No TI ulcers + FC < 150.

Conclusions 1 in 5 patients with isolated terminal ileitis are subsequently diagnosed with Crohn’s disease and almost 90% of these new cases have a faecal calprotectin > 150. There is poor correlation between endoscopic and histological terminal ileum ulceration. Terminal ileal ulceration in combination with a faecal calprotectin > 150 increases the likelihood of a new diagnosis of Crohn’s disease.