Parameters of bowel ultrasound in the assessment of IBD activity: a correlative study with clinical, endoscopic, and biomarker indices

Bowel ultrasonography (BUS) is becoming a viable, non-invasive, affordable, and radiation-free substitute for endoscopy, which is still the gold standard for evaluating Inflammatory bowel diseases activity. BUS can be used for diagnosis, activity evaluation, complication detection, and therapy monitoring. Our study aimed to evaluate the value of bowel ultrasound in evaluating IBD activity by analyzing the correlation between ultrasonographic parameters, clinical disease indices, endoscopic scores, and fecal calprotectin levels. This study included 62 Egyptian patients who were previously diagnosed with IBD. All participants underwent clinical assessment, intestinal ultrasound (IUS), fecal calprotectin (FCP) measurement, as well as endoscopy. Ultrasound parameters assessed included bowel wall thickness (BWT), bowel wall stratification, color Doppler signal (CDS), inflammatory fat, and lymphadenopathy. These parameters were correlated with clinical activity indices (SCCAI for UC and CDAI for CD), endoscopic scores (Mayo Endoscopic Subscore for UC and SES-CD for CD), and fecal calprotectin levels. Ultrasound-based scores HUC for UC and IBUS-SAS for CD were also evaluated. HUC correlated significantly with SCCAI and MES, while IBUS-SAS correlated with CDAI and SES-CD. Bowel wall thickness (BWT) was strongly associated with clinical and endoscopic indices in both UC and CD (all p ≤ 0.001), and color Doppler signal (CDS) showed similar significant correlations. BWT correlated with fecal calprotectin in UC, and CDS correlated with fecal calprotectin in CD. In ROC analysis, BWT demonstrated excellent accuracy for predicting active disease in CD (AUC 0.928; cutoff 3.25 mm; 84.6% sensitivity, 87.5% specificity) and in UC (AUC 0.927; cutoff 3.35 mm; 83.3% sensitivity, 100% specificity). Similarly, HUC yielded a strong diagnostic performance in UC (AUC 0.921; cutoff 5.43; 83.3% sensitivity, 100% specificity). CDS was predictive of disease activity in CD (AUC 0.889; 92.3% sensitivity, 87.5% specificity) but had lower discriminative value in UC (AUC 0.686, p = 0.064). Bowel ultrasound, particularly through BWT and CDS parameters, significantly correlates with established clinical, endoscopic, and biomarker indices, supporting its role for disease activity assessment in IBD.