Injury Severity Score as a Predictor for Requirement of Surgical Exploration in High Grade Renal Trauma

Introduction: With the current advances in intensive care protocols, conservative management is successful in a large proportion of renal trauma patients who are haemodynamically stable. In spite of the current trend towards conservative management of renal trauma, there still remains a dilemma regarding need for surgery in patients with grade IV renal trauma. Various predictors of failure of conservative management for high grade renal trauma have been studied. Aim: To assess the utility of the Injury Severity Score (ISS) in predicting the need for surgical exploration in patients with high grade renal trauma. Materials and Methods: We retrospectively studied 38 patients with renal injury over a period of 4 years. The Injury Severity Score (ISS) was calculated for all patients on admission. Renal injury grading on contrast enhanced computed tomography followed the American Association for the Surgery of Trauma (AAST) system. Patients were divided into three management groups: Group A-conservative management; Group B-double J ureteric stenting; and Group C-surgical exploration. The ISS in different management groups were compared using the Mann-Whitney U test. Results: Fifteen (39.47%) patients required intervention and 23 (60.5%) were managed conservatively. In the conserved Group A, 39.1%, 47.8% and 13% had injury grades 1, 2 and 3 respectively. Seven patients (18.4%) required ureteric stenting or pigtailing of perinephric collection (Group B) for urinary extravasation. All 7 had grade 4 injury. Eight patients (21.8%) were explored (Group C), out of which five had grade 4 injuries while three had grade 5 injuries. Average ISS in the 3 groups were 12.3, 11 and 19 respectively. Group C had significantly higher ISS than A (p=0.005) and B (p=0.0002). Of the grade 4 injuries, those who required surgical exploration had a higher ISS (17.80) compared to those who could be managed with minimal intervention (9.85); and this difference was statistically significant (p=0.007). ROC curve analysis showed an AUC of 0.863 for the predictive value of ISS for surgical exploration in renal trauma. Conclusion: Grade 4 renal injuries with a lower ISS can be managed with minimally invasive management in the form of double J stenting. The ISS can guide clinical decision making when faced with a dilemma of conservative vs surgical management of patients with high grade renal trauma.