Accuracy of Ultrasound for Evaluation of Colorectal Segments in Patients With Inflammatory Bowel Diseases: A Systematic Review and Meta-analysis

BACKGROUND & AIMS: The accuracy of ultrasound for evaluation of individual colorectal segments in patients with inflammatory bowel diseases (IBD) has not been evaluated in a systematic review. We evaluated the diagnostic accuracy of ultrasound in different colorectal segments of patients with IBD. METHODS: We searched publication databases from inception through March 2019 for studies that assessed the accuracy of ultrasound in detection of inflammation in right, transverse, and left colon and in rectum in patients with IBD, using findings from colonoscopy as the reference standard. Subgroup analyses were performed including IBD type, patient age, body mass index, and study design. The risk of bias was assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. RESULTS: Nineteen studies (1101 patients) were included in the qualitative synthesis. After we assessed the risk of bias, 7 studies (comprising 84 patients with Crohn's disease and 420 patients with ulcerative colitis) were included in the meta-analysis. Bowel wall thickness >= 3 mm identified colorectal segments with inflammation with 86.4% pooled sensitivity (95% CI, 76.1%-92.7%) and 88.3% pooled specificity (95% CI, 58.1%-97.6%). In rectum only, bowel wall thickness >= 3 mm identified inflammation with 74.5% sensitivity (95% CI, 53.0%-88.3%) and 69.5% specificity (95% CI, 33.6%-91.1%). Diagnostic accuracy was comparable among subgroups. Increased bowel wall flow and loss of stratification had higher true-positive odds ratios. CONCLUSIONS: Based on meta-analysis of patient-level data, ultrasound has higher diagnostic accuracy for detecting inflammation in colon than rectum in patients with IBD. Studies are needed to increase the accuracy of ultrasound detection of inflammation in rectum.