Intestinal ultrasound for the detection of postoperative recurrence in Crohn’s disease: a systematic review and meta-analysis

BACKGROUND AND AIMS: Postoperative recurrence of Crohn's disease (CD) is common and may occur without symptoms. Ileocolonoscopy is the reference standard for detecting endoscopic recurrence, but its invasiveness limits repeated use. Intestinal ultrasound (IUS) is a non-invasive monitoring tool, although diagnostic criteria and ultrasound modalities vary across studies. We conducted a systematic review and diagnostic test accuracy meta-analysis to evaluate the performance of IUS for detecting postoperative recurrence. METHODS: PubMed/MEDLINE, EMBASE, Scopus, and the Cochrane Library were searched from inception to April 2025. Eligible studies evaluated IUS for postoperative recurrence in CD using ileocolonoscopy as the reference standard. Data were extracted to reconstruct independent 2 × 2 diagnostic tables. The primary synthesis used hierarchical bivariate binomial random-effects models to jointly estimate summary sensitivity and specificity. Heterogeneity was explored through subgroup analyses by ultrasound modality, Doppler use, contrast route, bowel wall thickness threshold, diagnostic definition, data collection period, and recurrence severity. RESULTS: Twelve studies were included in the systematic review and narrative synthesis; 11 provided reconstructable independent 2 × 2 data and were included in the bivariate meta-analysis. IUS showed high summary sensitivity of 87.6% (95% CI, 81.0%-92.1%; P < .001) and good summary specificity of 80.2% (95% CI, 60.6%-91.5%; P < .001). The false negative rate was 12.4% (95% CI, 7.9%-19.0%), the false positive rate was 19.8% (95% CI, 8.5%-39.4%), positive likelihood ratio was 4.436 (95% CI, 2.070-9.505), negative likelihood ratio was 0.154 (95% CI, 0.101-0.236), and diagnostic odds ratio was 28.8 (95% CI, 11.0-75.4). Diagnostic performance was generally consistent across studies, although differences in ultrasound protocols and bowel wall thickness thresholds, most commonly ≥3 or ≥5 mm, appeared to contribute to between-study variability. CONCLUSIONS: IUS shows high sensitivity and good specificity for postoperative recurrence surveillance in CD. Its interpretation should remain linked to ultrasound protocol, threshold, recurrence definition, and clinical context.