This retrospective study of 8264 patients in the Western Trust aims to establish the threshold at which faecal calprotectin levels are correlated with colonoscopy findings.

The following retrospective observational study included a total of 8,264 patients who underwent colonoscopy at the Western Trust between 2022 and 2024. NIECR was used to view endoscopy reports. This allowed for a comparison of referral reasons and findings on colonoscopy, and subsequent correlation with FC  levels, if included in the referral.  Referral reasons included: raised faecal calprotectin over 50 µg/g, altered bowel habit, PR bleeding, IBD screening, IDA workup, and polyp/cancer screening. Findings on colonoscopy included polyps, Diverticulosis, haemorrhoids, known IBD, non-specific inflammation, tumours, new IBD, and normal findings.

Referral indications were: polyp/cancer screening (3,060), altered bowel habit (2,058), PR bleeding (1,627), iron deficiency anaemia (IDA) workup (446), raised FC  (413), and IBD assessment (660). The Colonoscopy findings included polyps (2,959), Diverticulosis (1,736), haemorrhoids (941), known IBD (453), non-specific inflammation (248), tumours (161), new IBD (63; CD 10, UC 53), and normal findings (1,689).

Among the 413 patients referred for raised FC, 25 (6%) were only diagnosed with new IBD (Female 10; Male 15; average age 46). The referral indications of the remaining 38 newly diagnosed  IBD patients were PR bleeding (12), IBD screening (8), altered bowel habit (9), polyp/cancer screening (5), and IDA workup (4).

The vast majority of new IBD cases (70%) had FC levels >300 µg/g. Interestingly, the scope findings in the remaining 350 patients referred with raised FC were, Haemorrhoids (43), 25% had FC levels >300 µg/g, Diverticulosis (98) 25% had FC levels >300 µg/g, Polyps (62) 29 % had FC levels >300 µg/g, indeterminate colitis and radiation proctitis (24) 37% had FC levels >300 µg/g, Tumour (7) 42 had FC levels >300 µg/g, Normal (116), 22% had FC levels >300 µg/g.

The study results affirm that although FC is as useful as a screening tool for IBD — particularly at levels greater than 300 µg/g — its value remains limited. One should be mindful of this when considering isolated rises in FC. Such results should be interpreted in the context of clinical presentation. Establishing a local threshold for FC-guided referral is thus essential to ensure appropriate use of endoscopy services for patients with gastrointestinal symptoms.