Traumatic Renal Artery Injuries: A Comprehensive Case Study Analysis

Introduction

Post-traumatic renal artery injury is a serious complication that can lead to the loose of the renal function by nephrotoxic damage. Thus, rapid resuscitation and restoration of circulating volume are imperative for preventing ongoing renal ischemia. Injuries affecting the kidneys represent around 1% to 5% of all cases, with the majority attributed to blunt abdominal trauma, accounting for 80% to 90% of these instances [1, 2]. Young men, typically engaged in sports, motor vehicle accidents, assaults, or falls (average age of 30), show a higher prevalence of traumatic renal injuries [1, 3].

Specific data solely on post-traumatic renal artery injury might be limited, making the precise determination of its incidence challenging. It appears that this incidence varies between 0.05% and 0.08% [4, 5, 6]. Thus, the occurrence of post-traumatic renal artery injury poses a significant concern among trauma patients. Even the kidney’s recuperation post open repair ranges widely, from 40% to below 10%, and remains largely unsatisfactory [6], Swift identification and proper intervention play pivotal roles in preserving renal function and avoiding complications especially the  risk of renovascular hypertension [5, 7].

We herein report three cases of renal ischemia due to post-traumatic injury to the main renal artery. Unfortunately, the diagnosis was late, at least 24 hours later. What is anecdotal, is that the interval between the first patient and the third is only three months, at a time when such lesions are rarely seen as described above.

Discussion

Even with renal artery injury, the mortality rate directly linked to kidney injury alone is typically low and often stems from the extensive presence of accompanying injuries. Bergqvist, et al. [8] reported an overall mortality of 6.5%, with a specific mortality rate related to renal injury recorded at 1.7%. Other studies described a total mortality of 0.6% [8, 9].

Renal trauma is categorized into five grades, ranging from minor injuries (Grade I) to severe injuries with vascular involvement (Grade V) [9, 10, 11]. Hence, we report three cases of renal artery injuries managed in our department within a very short period (a time span of 3 months between the first and third cases), regarding a condition considered rare with an incidence approaching. Although renal trauma is relatively rare, occurring in 1.4% to 3.2% of trauma cases [12, 13] and reaching up to 5% in certain series [1, 2], arterial injuries, as a subset of these cases, account for 0.05-0.08% of all trauma incidents [4, 5].

However, recent series, as indicated by Sangthong, et al. have reported an incidence of BRAI ranging from 1% to 4% among all abdominal injuries, which relies on the criteria used for abdominal CT evaluation [5]. Notably, a surge in the number of BRAI cases became apparent starting in 2005, coinciding with the widespread adoption of the 16-slice CT scanner [14].

All three of our patients were male, with an average age of 22.3 years, consistent with the predominant trend of younger males observed in most reported series. Chow, et al. reported a male-to-female sex ratio of 3.2:1 [14], while Petrone, et al. in their recent systematic review, found 75.3% of the patients to be male, with a mean age of 33 years [9].

Even with only three patients, two of them experienced injuries to the left kidneys. The left kidney is often observed to be slightly more susceptible to injury. Literature suggests a relative injury rate of 1.4:1 to 2:1 in favor of the left side compared to the right. Potential reasons for this include the shielding of the right renal artery by the inferior vena cava and duodenum, as well as its stabilization by the liver and duodenum [15].

It’s important to note, that renovascular injuries are frequently linked with concomitant injuries to non-renal organs, as observed in our cases and documented in other similar instances [9, 13, 15]. In our cases, we did not observe significant hemorrhage, and two cases had no hematuria. This might occur when renal artery injury leads to kidney devascularization through isolated intimal damage, causing thrombosis [15].

All our patients underwent a contrast-enhanced CT scan of the abdomen, which remains the gold standard for diagnosis [1, 3, 7, 15]. However, some authors propose considering contrast-enhanced ultrasound as the initial imaging modality in clinically symptomatic patients with minor blunt trauma and a negative extended focused assessment with sonography for trauma. Contrast-enhanced ultrasound could serve as an initial screening tool before resorting to a CT scan if the results are positive [16]. For hemodynamically unstable patients admitted urgently to the operating room, an intravenous urogram (IVU) might be considered. The objective is to analyze the morphological and functional aspects of both kidneys [17]. Unfortunately, for our patient operated on in an emergency, the IVU could not be performed due to an unsuitable operating table. What prompts the preoperative assessment is that nearly a quarter of post-traumatic renal injuries go unnoticed during emergency laparotomies [18, 19]. Moreover, the surgeon resorted to a manual palpation of the renal pedicle, which appeared intact. This is especially prominent in cases of arterial thrombosis, where patients might exhibit minimal or no retroperitoneal hematoma, an intact artery, and solely relying on palpation might lead to a missed diagnosis [20, 21].

In two cases, the absence of the cortical rim nephrogram sign, typically visible in devascularized kidneys, might not manifest in the acute setting [15, 22]. In our first case, there was approximately 5% of parenchyma, vascularized by small interlobar arteries.

Though CT scans remain the standard for overall renal injuries, arteriography stands as the gold standard for detecting renal artery injuries due to its dual advantage of injury identification and potential for endovascular interventions [23].

In our three cases, unfortunately, the diagnosis was delayed. As recognized, the most crucial aspect in preserving renal function is swiftly restoring blood flow. The ideal timeframe for revascularization remains a topic of debate and lacks clarity. While some authors propose a window spanning 6-12 hours, others have reported a narrower range of 3 to 4 hours [7, 15, 24], additional authors have suggested an attempt at revascularization before 20 hours of warm ischemia have passed [7, 25].

Moreover, even preserving renal function is more likely with a limited warm ischemic time, revascularization within four hours of warm ischemia doesn’t always guarantee optimal functional recovery [7, 26, 27]. Besides the duration until restoring blood flow to the primary renal artery, additional factors may influence renal function preservation. Notably, the presence of multiple thrombi in distal renal arteries. Illustrated in our first case, the estimated incidence of renal artery thrombosis following renal trauma is approximately 2% [28]. Delayed diagnosis dissuaded surgical revascularization attempts in our three cases, despite its minimal success rates, often resulting in recurrent thrombosis [5, 29]. Consequently, many surgeons refrain from this approach, especially when a functioning kidney is present on the opposite side [13, 15]. Recent studies have highlighted the potential of percutaneous revascularization using endovascular stenting for stable patients with unilateral renal artery occlusion [15, 23]. Unfortunately, our hospital lacks interventional radiologists for these procedures.

Determining the optimal management strategy remains challenging, as evidence is insufficient to identify subsets benefiting from open revascularization, endovascular therapy, or expectant management [23]. In a level 1 trauma center, Chow, et al. employed angiography and embolization in 34.3% of cases [14], while some advocate for open surgery in urgent scenarios.

Current consensus suggests that open revascularization is not recommended if a functioning contralateral kidney exists [4, 12, 13, 14, 27]. Non-operative management remains important due to poor outcomes following urgent surgical revascularization, with an estimated preserved kidney rate of less than 20% [29]. Selective arterial embolization via angiography emerges as a less invasive alternative to laparotomy, boasting a success rate exceeding 90% [30].

Nine months post-injury during the follow-up, two patients did not require antihypertensive medication and had normal blood pressure readings. For the first patient, we did not receive any updates. Indeed, urgent management of renal artery injury is aimed at preserving kidney function and preventing renovascular hypertension, thereby reducing the likelihood of necessitating secondary nephrectomy [5, 12, 26, 29]. Haas, et al. reported Thirty-four out of 105 patients (32%) who did not undergo attempted revascularization experienced the onset of hypertension [12].

Conclusion

Post-traumatic renal artery injuries pose significant challenges in timely diagnosis and appropriate management, particularly given their rarity and potential for severe complications. The cases presented underscore the limitations in prompt identification and intervention, resulting in delayed attempts at surgical revascularization and highlighting the lack of available resources for alternative procedures in our hospital. The limited success rates of surgical revascularization and the associated risk of recurrent thrombosis have led to a reevaluation of the management approach, with a shift toward non-operative methods and less invasive techniques. However, establishing the optimal management strategy remains a challenge due to inadequate evidence on the effectiveness of different approaches. Urgent management aims to preserve renal function and prevent secondary complications, necessitating further research and standardized protocols to enhance outcomes in these cases. Long-term follow-up revealed varied outcomes, emphasizing the need for comprehensive management and continued monitoring in post-traumatic renal artery injuries.