Computed tomography in the initial evaluation of hemodynamically stable patients with blunt abdominal trauma: Impact of severity of injury scale and technical factors on efficacy

Background: Although computed tomography is used widely in evaluating injuries from blunt abdominal trauma, grading of injuries does not reliably predict the need for intervention, Objective reporting is essential to evaluate accuracy and facilitate patient triage. We established and tested a five-point grading system for overall severity of injury. Methods: A total of 392 computed tomographic trauma cases were objectively classified according to the type and severity of abdominal injuries, by two experienced radiologists. Interobserver variability between the original interpretation and the consensus of the film reviewers was evaluated. The computed tomographic grading system was measured against rate of admission, exploratory laparotomy, and further imaging. Results: Patients with higher grades of injury on computed tomography were increasingly likely to have surgical management (odds ratio, 3.99; 95% confidence interval, 1.86-8.58; p < 0.0006), with sensitivity 100%, specificity 89.5% for level 2 injuries and higher. Although there was almost perfect agreement between the official interpretation and the reviewers' blinded consensus interpretation (raw agreement 84%, weighted kappa 0.86), indeterminate studies were reduced from 23% (16 of 67) to 12% (8 of 67) on review: these were more likely to have metallic or motion artifacts (5 of 16 vs. 1 of 51 p < 0.002). Conclusions: Standardizing reporting of injuries enhances accuracy, and grading eliminates equivocation, Diagnostic certainty in computed tomography of blunt abdominal trauma is reduced by motion and metallic artifacts.