Bowel ultrasound scan in the management of pediatric moderate ulcerative colitis: The applicability of international bowel ultrasound segmental activity score

OBJECTIVES: To evaluate bowel ultrasound (BUS) findings and the diagnostic and prognostic performance of international bowel ultrasound segmental activity score (IBUS-SAS) in children with moderate ulcerative colitis (UC), including its accuracy for assessing endoscopic activity and predicting clinical remission and colectomy within 12 months. METHODS: This was a single-center retrospective study conducted at Meyer Children's Hospital IRCCS. All patients who underwent a BUS performed for moderate UC (defined as pediatric ulcerative colitis activity index 35-60, either at disease onset or at relapse) between January 2019 and December 2023 were included. Where available, data on ileocolonoscopy performed within 4 weeks before or after BUS were retrieved, if no changes in medical management were performed during this period. RESULTS: Seventy-seven patients were included; 35/77 (45.5%) underwent ileocolonoscopy within 4 weeks from BUS. The most common BUS finding was increased colonic wall thickness (74/77, 96.1%), followed by enhanced vascularization (70/77, 90.9%). Loss of wall stratification was observed in 15 of 77 BUS (19.5%). The discriminative ability of IBUS-SAS in identifying moderate endoscopic activity was appraised through a receiver operating characteristic curve, showing a good area under the curve (0.75, 95% confidence interval [CI]: 0.58-0.90, p = 0.021) with an optimal cut-off of 48.5. IBUS-SAS ≥ 49 (as nominal variable) was identified as independent predictor of clinical remission (adjusted hazard ratio:0.42, 95% CI: 0.23-0.78) and colectomy within 12 months (adjusted odds ratio:4.18, 95% CI: 1.03-16.91). CONCLUSIONS: BUS is a non-invasive, repeatable tool for monitoring disease activity and stratifying pediatric UC with moderate activity. IBUS-SAS showed good discriminative ability for endoscopic activity, supporting its use for ultrasound-based risk-stratification in this setting.