Does a collecting system injury with grade iv renal blunt trauma always need urinary intervention?

PURPOSE: This study aimed to identify the characteristics associated with the need for urinary intervention for a blunt renal injury with collection system involvement using a computed tomography (CT) protocol for trauma.

MATERIALS AND METHODS: Abdominal CT images of patients with blunt renal injuries from 2016 to 2020 were reviewed. Patients with low-grade renal trauma, non-collecting system involvement, American Association for the Surgery of Trauma grade V shattered kidney, and emergent nephrectomy were excluded. The largest perinephric mass thickness was measured in the axial view using CT, and a cutoff value was obtained using a receiver-operating characteristic curve analysis. Risk factors for further urinary intervention were analyzed.

RESULTS: Among the 70 patients included in this study, those with perinephric mass thicknesses < 25 mm (n = 36) had a significantly lower rate of urinary intervention than those with perinephric mass thicknesses ≥ 25 mm (0 vs. 5; p = 0.023). There was no significant difference in the follow-up durations of the groups (19 days vs. 38 days; p = 0.198). More than 90% of the perinephric mass in the < 25 mm group resolved within a median follow-up duration of 38 days, whereas nearly half of the ≥ 25 mm group had a residual perinephric mass during a median follow-up duration of 19 days.

CONCLUSION: The initial CT protocol for trauma was useful for predicting the need for further urinary interventions for collecting system injuries. A perinephric mass thickness < 25 mm is predictive of a low likelihood of requiring urinary intervention.