Purpose: Guidelines call for routine reimaging of Grade 4-5 renal injuries at 48-72 h. The aim of the current study is to evaluate the clinical utility of computed tomography (CT) reimaging in high-grade renal injuries.
Materials and methods: We assembled data on 216 trauma patients with high-grade renal trauma at three level 1 trauma centers over a 19-year span between 1999 and 2017 in retrospectively collected trauma database. Demographic, radiographic, and clinical characteristics of patients were retrospectively reviewed.
Results: In total, 151 cases were Grade 4 renal injuries, and 65 were Grade 5 renal injuries. 53.6% (81) Grade 4 and 15.4% (10) Grade 5 renal injuries were initially managed conservatively. Of the 6 asymptomatic cases where repeat imaging resulted in intervention, 100% had collecting system injuries at initial imaging. Collecting system injuries were only present in 42.9% of cases where routine repeat imaging did not trigger surgical intervention. Collecting system injury at the time of initial imaging was a statistically significant predictor of routine repeat imaging triggering surgical intervention (p = 0.022). Trauma grade and the presence of vascular injury were not significant predictors of intervention after repeat imaging in asymptomatic patients.
Conclusion: In asymptomatic patients with high-grade renal trauma, the number needed to image is approximately one in eight (12.5%) to identify need for surgical intervention. There is potentially room to improve criteria for routine renal imaging in high-grade renal trauma based on the more predictive imaging finding of collecting system injury.
Keywords: Collecting system injury; High-grade renal trauma; Renal trauma grade; Repeat imaging; Vascular injury.