Four intestinal ultrasound scores and bowel wall thickness alone correlated well with pediatric ulcerative colitis disease activity.

Objectives: Intestinal ultrasound (IUS) is a noninvasive tool in ulcerative colitis (UC), but scoring systems have mostly been developed for adults, Crohn's disease, and flaring UC. Our aim was to evaluate the performance of bowel wall thickness (BWT) and four IUS scores in pediatric patients with newly diagnosed UC.

Methods: Patients <18 years old with suspected UC were prospectively enrolled. Baseline IUS was done, and ulcerative colitis intestinal ultrasound score (UC-IUS), Milan criteria, simple pediatric activity ultrasound score (SPAUSS), and Civatelli Index were calculated. Mayo endoscopic segment subscore, pediatric ulcerative colitis activity index (PUCAI), and biomarkers were correlated with IUS using nonparametric and receiver operating characteristic analyses.

Results: Fifty-two patients (56% male, median age 13.9 years, interquartile range [IQR] 11.2-16.3) with 206 colon segments were included. Patients who needed hospitalization (n = 27/52) had significantly worse IUS (BWT and all scores) compared to those not hospitalized. For all patients, IUS scores and BWT significantly correlated with baseline endoscopic, clinical, and biochemical disease activity (p = 0.32-0.67, p < 0.05). BWT (τ_b = 0.53), UC-IUS (τ_b = 0.55), and Milan (τ_b = 0.52) had the strongest endoscopic correlations. For differentiating between endoscopic disease severity, BWT, UC-IUS, and Milan, had the highest areas under the curve (0.89-0.93). Using BWT alone, a thinner cut-off had improved sensitivity while maintaining high specificity: ≥2.5 mm for moderate/severe endoscopic inflammation (sensitivity 66%; specificity 94%) and ≥3.5 mm for severe endoscopic inflammation (sensitivity 92%; specificity 86%).

Conclusions: BWT and all four IUS scores correlated well with endoscopic, clinical, and biochemical disease activity, and was another useful marker of severity in identifying patients needing hospitalization. Pediatric patients needed a thinner BWT cut-off, which should be accounted for when developing pediatric-specific scores. BWT alone may be just as clinically useful as composite US scores.