Introduction and Overview

Renal injury occurs in approximately 1.2% to 3.3% of all trauma patients and represents a common cause of morbidity and mortality.¹ Conservative (or nonoperative) management has been established as the preferred approach for most injuries, including high grade.^1-3 The goal of renal trauma management is to stabilize the patient while making every effort to preserve the kidney and obviate nephrectomy. Contemporary studies have shown that 15% of grade IV and 62% of grade V renal trauma ends in nephrectomy.^1,4 However, conservative management of high-grade renal trauma (HGRT) has become more prevalent over the last 20 years with 70% to 90% of all HGRT and 30% to 60% of grade V renal injuries now being managed conservatively with an estimated 70% to 90% success rate.^4-9 This article provides an overview of recent developments in HGRT conservative management.

Patient Selection

CT scan is the gold standard for imaging, although ultrasound may be used to look for renal contusion or free fluid. Nonoperative management includes supportive care, bed rest, and vital sign monitoring. A subset of renal trauma cases are not stable enough for imaging and go directly to operating room. Other indications for intervention (angioembolization or surgery) include hemodynamic instability with no or transient response to resuscitation, radiographic findings of large or pulsatile hematoma (>4 cm), and/or vascular contrast extravasation with significant renal injury.² Conservative management is currently recommended for HGRT in hemodynamically stable patients, and it may be considered for hemodynamically unstable patients who respond to resuscitation.² Clinical characteristics of patients with grade V renal trauma from the NTDB (National Trauma Data Bank) are shown in Table 1, and multivariable analysis of factors associated with receiving conservative management in this population are shown in Table 2 and Figure 1.

Table 1. Clinical Characteristics of Patients With Grade V Renal Trauma Who Survived to Discharge, Stratified by Management Approach

Table 2. Multivariable Analysis of Factors Associated With Receiving Conservative Management Adjusting for Age, Sex, Penetrating Mechanism, Transfusion, Pulse Rate, Glasgow Coma Scale, Hypotension, Trauma Center Level, and Presence of Any Associated Injury

Utility of Conservative Management

Conservative management may be employed in some of the most severe renal trauma phenotypes. In a recent analysis of the NTDB, over one-third of patients with grade V injuries were successfully managed conservatively.³ Conservative management appeared to be a safe approach as it was not associated with increased mortality.³ Moreover, data from the Multi-institutional Genito-Urinary Trauma Study demonstrated that 60% of patients with grade V injuries were managed nonoperatively, 60% of whom underwent minimally invasive treatment with angioembolization or ureteral stent placement.⁵ HGRT conservative management failure rates range from 8% to 27%.^5-9 Factors associated with decreased utility and effectiveness of conservative management are generally homogenous in the literature and include poor hemodynamic parameters, penetrating injuries, and larger hematoma size on imaging. Other studies have demonstrated that patients managed nonoperatively have fewer in-hospital complications and shorter ICU stay.^6,7

Angioembolization

Angioembolization represents a less invasive option compared to surgery and has become increasingly popular over the last 20 years (Figure 2), although it is likely underutilized.⁶ In one study comparing angioembolization to surgery, the former was associated with lower odds of nephrectomy and thus higher kidney salvage with angioembolization.⁴ Angioembolization failure rates in HGRT vary from 0% to 30% in the literature and have been associated with higher-grade injury, hemodynamic instability, and larger perirenal hematoma.^4,6,8 Notably, initial failure of angioembolization appears to result in negligible mortality, and repeat angioembolization may be considered.⁸ Some studies have found no differences in outcomes of angioembolization based on hemodynamic stability status, suggesting primary angioembolization may be a viable option, even for those with some hemodynamic instability.^2,6 Limited literature exists regarding the long-term follow-up results for those managed with angioembolization; however, predictors of conservative management failure can also include nonkidney-related factors. Some studies have demonstrated that presence of concomitant abdominal injuries can be motivating factors for kidney interventions.⁷