Abstract Background Early small bowel Crohn’s disease (CD) in children is difficult to identify because growth impairment and chronic gastrointestinal (GI) symptoms often occur despite normal inflammatory biomarkers. Intestinal ultrasound (IUS) can detect early mural abnormalities, but its diagnostic performance across predefined terminal ileum (TI) segments has not been studied. We evaluated segment-level concordance between IUS and deep ileocolonoscopy in biomarker-negative children with suspected early small bowel CD. Methods We conducted a prospective IUS-triggered selective ileocolonoscopy study. IUS was performed by a paediatric imaging expert in primary care, and only children showing Crohn’s-suspicious IUS abnormalities were referred to a tertiary paediatric IBD centre for selective deep Ileocolonoscopy, creating a highly enriched pre-test probability cohort. For analysis, the TI was divided into three predefined segments, and each segment was assessed independently. IUS abnormality was defined as bowel wall thickening 3 mm and/or loss of stratification. Endoscopic abnormality was defined as any inflammatory lesion. Segment-level sensitivity, specificity, positive predictive value (PPV), accuracy, and Cohen’s κ were calculated Results Twenty-nine children (mean age 10.4 ± 3.4 years; 59% male) were included. Most had normal biomarkers (median CRP 0.2 mg/dL; faecal calprotectin 12 µg/g), consistent with a biomarker-negative early CD phenotype. Endoscopic inflammation was observed in 97%, 86%, and 66% of TI segments 1, 2, and 3, respectively. Corresponding IUS abnormalities were present in 100%, 76%, and 55%. Segment-level performance of IUS: • Segment 1:sensitivity 100%, PPV 96.6%, accuracy 96.6%. • Segment 2:sensitivity 84.0%, specificity 75.0%, PPV 95.5%, accuracy 82.8%, κ = 0.45. • Segment 3: sensitivity 68.4%, specificity 70.0%, PPV 81.3%, accuracy 69.0%, κ = 0.36. Inflammation showed non-uniform, segmental distribution across the TI, indicating intra-ileal heterogeneity even in early disease. IUS consistently identified segment-level abnormalities with high PPV. Conclusion In biomarker-negative children with suspected early CD, an IUS-triggered selective ileoscopy strategy identified a highly enriched cohort with segmental TI inflammation. IUS demonstrated high PPV and moderate segment-level concordance, supporting its use to guide selective, deep, segment-based ileal assessment for early detection of paediatric small bowel CD. Conflict of interest: Dr. Lee, Eun Joo: No conflict of interest Lim, Hyun Ji: No conflict of interest
Lee et al. (Thu,) studied this question.