Role of Ultrasound Elastography in the Detection of Fibrotic Bowel Strictures in Patients with Crohn's Disease: Systematic Review and Meta-Analysis

PURPOSE: To perform a systematic review with meta-analysis to assess whether ultrasound elastography can have a diagnostic role in detecting fibrotic bowel strictures in patients with Crohn's disease. MATERIALS AND METHODS: MEDLINE via the PubMed, Ovid Embase, Scopus and Cochrane Library databases, and abstracts of international conference proceedings were searched up to March 31, 2018. Studies were included if they assessed the performance of abdominal ultrasound elastography in detecting fibrotic bowel strictures in patients with Crohn's disease using histology or the need for surgery after medical treatment as a reference standard. The quality of the studies was assessed using Quality Assessment of Diagnostic Accuracy Studies. RESULTS: 6 studies including a total of 217 patients with Crohn's disease and 231 bowel segments, of which 76 were bowel segments with fibrotic stricture, were selected. Three studies used strain ratio and three studies used strain value as parameters of bowel stiffness. Both the pooled standardized mean strain ratio and the pooled standardized mean strain value were higher in bowel segments with fibrotic strictures than in those without fibrotic strictures with a standardized mean difference of 0.85 (95 % confidence level [CI]: 0 to 1.71; p = 0.05) and 1.0 (95 % CI: -0.11 to 2.10; p = 0.08), respectively. There was a high heterogeneity between studies. All studies were at "high risk" or "unclear risk" of bias. CONCLUSION: Ultrasound elastography could be able to detect fibrotic bowel strictures in patients with Crohn's disease. Well-designed high quality diagnostic studies with a large sample size are needed.