High grade renal injuries: application of Parkland Hospital predictors of intervention for renal hemorrhage.

PURPOSE: Investigators from Parkland Hospital proposed substratification of the AAST (American Association for the Surgery of Trauma) grading scale based on 3 risk factors, including active vascular extravasation, a medial laceration and a perinephric hematoma of greater than 3.5 cm. We hypothesized that these characteristics would also be associated with intervention for renal hemorrhage in our large trauma series.

MATERIALS AND METHODS: From January 2005 to January 2011 we retrospectively reviewed the renal trauma records at adult level 1 trauma centers in Utah. AAST grade 3 and 4 injuries were characterized based on the mentioned 3 risk factors. Our primary outcome was intervention to control renal hemorrhage.

RESULTS: AAST grade 3 or greater injury was identified in 147 patients, including 115 who had grade 3 and 4 injuries as well as imaging available for review. There were 63 grade 3 (53%) and 52 grade 4 (43%) renal injuries. Eight patients (7%) underwent intervention for renal hemorrhage. Vascular extravasation (OR 16.4, 95% CI 2.6-179.8, p <0.001) and perinephric hematoma greater than 3.5 cm (OR 8.4, 95% CI 1.4-52.5, p = 0.0099) were associated with intervention, while a medial laceration was not (p = 0.454). Patients with 1 or fewer, 2 and 3 risk factors had an intervention rate of less than 2.9%, 18% and 50%, respectively (p <0.001).

CONCLUSIONS: Vascular extravasation, a perinephric hematoma greater than 3.5 cm and the number of risk factors (0 to 3) were associated with intervention for renal hemorrhage. Our findings are similar to those at Parkland Hospital. These imaging features may serve as useful prognostic indicators for renal trauma.