Test Characteristics of Chest Ultrasonography for Rib Fractures Following Blunt Chest Trauma: A Systematic Review and Meta-analysis

Abstract

Chest ultrasonography has been reported as an accurate imaging modality and potentially superior to chest radiographs in diagnosing traumatic rib fractures. However, few studies have compared ultrasonography to the reference standard of computed tomography (CT), with no systematic reviews published on the topic to date. Our objective was to summarize the evidence comparing the test characteristics of chest ultrasonography to CT in diagnosing rib fractures. This study was performed and reported in adherence to PRISMA guidelines. We searched 5 databases plus gray literature from inception to October 2021. Two independent reviewers completed study selection, data extraction, and a QUADAS-2 risk of bias assessment. Summary measures were obtained from the Hierarchical Summary Receiver Operating Characteristic model. From 1,660 citations, we identified 7 studies for inclusion, of which 6 had available 2×2 data for meta-analysis (n= 663). Of the 6 studies, 3 involved emergency department-performed ultrasonography and 3 radiology-performed ultrasonography. Chest ultrasonography had a pooled sensitivity of 89.3% (95% confidence interval [CI], 81.1 to 94.3) and specificity of 98.4% (95% CI, 90.2 to 99.8) compared with CT imaging for the diagnosis of any rib fracture. The finding of a fracture on ultrasonography, defined as an underlying cortical irregularity, was associated with a+likelihood ratio (LR) of 55.7 (95% CI, 8.5 to 363.4) for CT diagnosed rib fracture, while the absence of ultrasonography fracture held a -LR of 0.11 (95% CI, 0.06 to 0.20). We were unable to detect a difference in test characteristics between emergency department- and radiology-performed ultrasonography (P=.11). The overall risk of bias of included studies was high, with patient selection identified as the highest risk domain. Chest ultrasonography is both sensitive and highly specific in diagnosing rib fractures following blunt trauma.