Renal infarction is a rare ischemic event caused by complete or partial occlusion of the main renal artery [4]. Bourgault et al. presented a case series, collected retrospectively between 1989 to 2011 including 94 cases [5]. In the study, they classified the etiology of renal infarction into 4 groups: cardiac group, renal injury, hypercoagulable group and idiopathic group. However, trauma related renal artery infarction wasn’t mentioned specifically. In 2019 Ana et al.’s systemic review, cardiac or aortic embolism was responsible for 45.4% of the reported cases, which was the leading cause [6].

Among blunt abdomen trauma cases, renal injury was not uncommon, about 1-5% [7]. However, blunt trauma with renal vascular injury was rare, about 0.05-0.08% [8, 9]. Tracing back the history of blunt trauma related renal artery injury, the earliest case had been reported in 1861 by Von Recklinghausen [10]. Increasing cases was found during early 1900s. In 1927, Neuburger hypothesized trauma causing renal artery spasm leading to further infarction. However, thrombosis of main artery had been demonstrated by Barney and Mintz through autopsy in 1933 [10]. Clark D.E. in 1981 had demonstrated 10 such cases and review 240 cases from previous literature, the renal vascular injuries could be described as avulsion in 12% of cases, laceration in 4% of cases, thrombosis in 44% cases, intimal flap in 7% and arterial spasm in 4% of cases [1]. There were 2 possible mechanisms of blunt trauma induce renal artery thrombosis [11]. First, the acute deceleration caused stretching of renal artery, leading to intima disrupt, exposing the endothelium and initiated thrombotic cascade. This concept was support by the observation that left renal artery was more vulnerable to such blunt trauma compared to right renal artery, which was surrounded by inferior vena cava and duodenum, causing less motion [12,13]. Hass et al. demonstrated similar concept that left renal artery injury was more common than right side with a ratio of 1.4:1-1.2:1. He also explained by the more acute angle of left renal artery to abdomen aorta, causing more stretching during blunt injury [14]. Second, it was believed that renal vessels had been compressed against vertebral body, causing intimal damage [13]. Currently, abdomen dynamic contrast CT could detect the occlusion of renal artery accurately [13,15].

Current treatment options for acute renal infarction included catheter direct thrombolysis, systemic thrombolysis, anticoagulation and surgery [4]. However, the role of revascularization by any means hadn’t been well established. Mulayamkuzhiyil Saju suggested revascularization was indicated in following circumstances: complete occlusion of main or major segmental renal artery < 6 hours duration, solitary kidney, or significant reduction of GFR from baseline (<50ml/min GFR); partial occlusion of main or major segmental renal artery of <24 hours duration or had persisted hypertension, flank pain, renal failure; a renal infarction associated with arterial dissection [4, 16-18]. However, if we narrowed down the population to blunt trauma related renal artery injury, the optimal approach was less clear due to small sample size. Jaws A. also mentioned the preference of conservative treatment because of delay in diagnosis and that revascularization not always resulted in return of renal function [2]. Open surgical revascularization had seldom been done due to poor preserved renal function rate, about 14-29% from previous literature [19]. For less invasiveness and maturing tools, percutaneous endovascular revascularization had risen, gaining more expectation. Percutaneous endovascular revascularization by stent placement following blunt trauma related renal injury had first been demonstrated in 1995 [3]. Yu-Wei Tsao had reported similar case that the renal function successfully improved after thrombosuction and stent placement in 2016, as first case been reported in Taiwan [20]. In 2017, Jahangiri, Y. had collected 54 cases undergone percutaneous endovascular revascularization for blunt trauma related renal arterial thrombosis [21]. Most cases had stent placement with 2 cases for PTA alone, 1 for thrombosuction alone and 1 for thrombolysis alone. The time to intervention interval lasts about 4-12 hours in general with 48 hours. Technical success was achieved in 88.9% cases and clinical success in 75% cases after 6 months follow-up. 6 technical failure cases had following 3 reasons: failed recanalization (3 cases), failed guidewire passage (2 cases) and persistent notch between stents (1 case) [22-24]. Within technical success group, 12 clinical failure cases showed persistent occlusion of the renal artery (10 cases) and renal artery dissection (2 cases) [23, 25-34]. During sub-group analysis, predictors of clinical success included total occlusion of renal artery on presentation and post-procedure anti-platelet treatment (aspirin, clopidogrel or both), while time to intervention didn’t cause significant difference [21].

In our case, we demonstrated a case with blunt trauma related renal artery thrombosis successfully treated by endovascular therapy. After angioplasty and stent placement with post-procedure dual-antiplatelet, his renal function gradually improved and creatinine level completely returned to baseline in 22 days. Though the time to intervention didn’t play important role in previous study [21] , we believed that prompt intervention before tissue necrosis still posed significant role leading to dramatic improvement of renal function in our case.