Accuracy of gastrointestinal ultrasound and calprotectin in the assessment of inflammation and its location in patients with an ileoanal pouch.

BACKGROUND AND AIMS: In symptomatic patients with ileoanal pouches, pouchoscopy is needed for accurate diagnosis, but is invasive. We aimed to assess the utility of non-invasive gastrointestinal ultrasound and faecal calprotectin in ileoanal pouch patients. METHODS: Patients with an ileoanal pouch were consecutively enrolled in this cross-sectional study from clinics in Victoria, Australia. The pouchitis disease activity index was used as a reference standard. Video-recorded pouchoscopies were reviewed by three gastroenterologists. Pouch, pre-pouch and cuff biopsies were reviewed by a single pathologist. Ultrasound was performed by a single gastroenterologist transabdominally and transperineally. Faecal calprotectin was measured from morning stool samples. All examiners were blinded to patients' clinical history. RESULTS: 44 participants had a pouchoscopy, of whom 43 had a faecal calprotectin and 42 had an ultrasound. 17 had pouchitis, 15 had pre-pouch ileitis, and 16 had cuffitis. Pouch wall thickness of <3 mm was 88% sensitive at excluding pouchitis, and pouch wall thickness of ≥4 mm was 87% specific at diagnosing pouchitis. Transabdominal ultrasound had good utility (area-under-the-curve 0.78) in diagnosing moderate-severe pre-pouch ileitis. Transperineal ultrasound had good utility for the diagnosis of pouchitis (area-under-the-curve 0.79). Faecal calprotectin differentiated inflammatory from non-inflammatory pouch disorders such as irritable pouch syndrome with an area-under-the-curve of 0.90. Faecal calprotectin <100 µg/g ruled out inflammatory pouch disorders with a sensitivity of 94%. CONCLUSION: Faecal calprotectin and ultrasound are accurate and complementary tests to diagnose and localise inflammation of the ileoanal pouch. Prospective studies are needed to validate proposed sonographic indices and calprotectin levels.