External validation of the MiGUTS nomogram following predominantly penetrating renal trauma in a South African population.

INTRODUCTION

The management of high-grade renal trauma (HGRT) is challenged by the limitations of the American Association for the Surgery of Trauma (AAST) renal trauma grading system. To enhance predictive accuracy for bleeding control interventions, Keihani et al. introduced the Multi-Institutional Genito-Urinary Trauma Study (MiGUTS) in 2019. This study aims to externally validate the MiGUTS nomogram using a South African Level 1 trauma center cohort with a unique penetrating predominant population.

METHODS

Data were collected retrospectively from June 2021 to December 2023 at Tygerberg Hospital, encompassing all patients aged ≥ 18 years with AAST ≥ 3 renal trauma who underwent abdominal computed tomography imaging. Two blinded radiologists reviewed each scan. The nomogram incorporated trauma mechanism, hypotension/shock, concomitant injuries, vascular contrast extravasation (VCE), pararenal hematoma extension, and hematoma rim distance (HRD). Predictive accuracy was evaluated using the area under the receiver operating characteristic curve (AUC) and its 95% confidence interval (CI).

RESULTS

A total of 129 patients were included; 74% had penetrating trauma, and the median age was 30 years. Bleeding intervention was required in 12% (6 nephrectomies, 9 angioembolizations). Using the MiGUTS nomogram we obtained an AUC of 0.80, with a sensitivity of 0.73, specificity of 0.64, positive predictive value of 0.21, and negative predictive value of 0.95.

CONCLUSION

While the MiGUTS nomogram demonstrated high discriminatory power in our cohort, our AUC of 0.80 fell outside the 95% confidence interval reported by Keihani et al. Differences in trauma mechanisms, particularly the high rate (74%) of penetrating injuries, suggest a need for an adjusted nomogram for penetrating renal trauma.