Transabdominal Intestinal Ultrasound for the Assessment of Ileal Disease Activity in Crohn's Disease.

Abstract

Background and study aims: Transabdominal intestinal ultrasonography (IUS) is increasingly used to assess transmural inflammatory activity in Crohn's disease (CD). This study evaluated the diagnostic performance of IUS for detecting ileal inflammatory activity in CD by comparing individual ultrasonographic parameters and composite activity scores with ileocolonoscopy.

Patients and methods: This single-center retrospective study included patients with CD with ileal involvement who underwent ileocolonoscopy and transabdominal IUS within a 7-day interval. Ileal endoscopic activity was assessed using the Simple Endoscopic Score for Crohn's Disease (SES-CD), with a score ≥3 indicating active disease. Ultrasonographic evaluation included bowel wall thickness (BWT), color Doppler signal (CDS), their combined assessment, and composite scores: International Bowel Ultrasound Segmental Activity Score (IBUS-SAS), Simple Ultrasound Score for Crohn's Disease (SUS-CD), and Bowel Ultrasound Score (BUSS). Endoscopic findings served as the reference standard.

Results: Fifty patients were analyzed. Increased BWT and the presence of CDS were significantly associated with higher ileal SES-CD scores. When evaluated individually, BWT and CDS demonstrated moderate sensitivity and high specificity for endoscopically active disease. Among composite scores, SUS-CD showed the highest sensitivity and overall accuracy, whereas IBUS-SAS and BUSS demonstrated high-specificity profiles. ROC analysis identified an optimal BWT cut-off of 3.69 mm, providing improved specificity compared with the conventional 3-mm threshold.

Conclusion: Transabdominal intestinal ultrasound shows high specificity for detecting ileal inflammation in Crohn's disease. Individual ultrasonographic parameters and composite ultrasound activity scores may serve as useful noninvasive adjuncts to endoscopic assessment of ileal disease activity.