Department of Medical Imaging and Intervention, Linkou Chang Gung Memorial Hospital, Chang Gung University, Linkou, Taiwan

Transcription

1 J Radiol Sci 2015; 40: Renal Artery Embolization in Patients with Blunt Renal Trauma: Evaluating the Efficacy of the Procedure and the Impacts on Renal Function and Blood Pressure - a retrospective case series study Chien-Wei Chen Li-Jen Wang Cheng-hsien Wu huan-wu Chen Yon-Cheong Wong Department of Medical Imaging and Intervention, Linkou Chang Gung Memorial Hospital, Chang Gung University, Linkou, Taiwan ABSTRACT To evaluate the impact of renal artery embolization (RAE) on renal function and blood pressure (BP) in patients with blunt renal trauma (BRT). This retrospective study was approved by institution review board of a level I trauma center. Over an 8-year period, 64 patients with BRT underwent RAE. The measurements of renal function and BP were obtained at admission, and followed up for the duration between 4 days and 12 months. Patients who died during hospitalization were excluded from the renal function and BP analysis. Variables were recorded and analyzed using uni-and-multivariate tests. Binary logistic regression was used to compute the predictive factors for mortality. Technical success (complete occlusion of the vascular lesions) rate was 96.9% (n = 62), clinical success (keeping alive and complete cessation of bleeding without the need for further procedure) rate was 85.9% (n = 55), and mortality rate was 9.4% (n = 6). Predictive factors of age 60 years (OR = 10.1, p = 0.023) and multiple-organinjury ( 2 organs in addition to kidney; OR = 8.7, p = 0.015) were significant for mortality. The value of AUROC (Area under the Receiver Operating Characteristic Curve) was indicating that the model has excellent accuracy. Forty-four patients (n = 44, 68.8%) had renal-related complications, in which, thirty-seven (n = 37, 84.1%) resolved after conservative treatment. Renal function analysis showed significant improvements in serum creatinine, egfr (MDRD formula) and renal function stage (National Kidney Foundation) after RAE (p < 0.001). BP analysis showed significant elevation in diastolic BP (p = 0.017) and mean arterial pressure (p = 0.018) after RAE. The number of patients with normal BP (stages 2 and 3) was significantly increased after RAE (p < 0.001). RAE is the treatment of choice for patients with severe renal trauma because of its high technical and clinical success rates. RAE, with discretion, can preserve renal function and restore normal BP after the procedure. INTRODUCTION Acute renal bleeding due to external trauma is a potentially life-threatening event that requires rapid clinical evaluation and treatment. Although most patients can be managed by observation, those with hemodynamic instability or vascular abnormalities require surgical or endovascular intervention [1]. Renal trauma accounts for approximately 3% of all trauma admissions and 10% of patients who sustain abdominal trauma [2]. Blunt renal trauma (BRT) accounts for the largest percentage of acute renal injuries (93.4%) and requires critical care [3, 4]. Previous reports in small case series indicated that renal artery embolization (RAE) is an effective treatment of iatrogenic and penetrating renal injuries as well as blunt renal injuries [5-8]. Although many advantages of RAE have been reported (e.g., minimal invasion and shorter duration of hospitalization), potential side effects remain unclear. The Correspondence Author to: Yon-Cheong Wong Department of Medical Imaging and Intervention, Linkou Chang Gung Memorial Hospital, Chang Gung University, Linkou, Taiwan No. 5, Fu-Shing Street, Kwei-Shan, Taoyuan 33305, Taiwan J Radiol Sci December 2015 Vol.40 No.4 115

2 main concerns regarding embolization are adverse events that may result from devascularization of renal parenchyma, with subsequent loss of renal function as well as hypertension caused by renin secretion [9]. While some small case series with different populations (e.g., traumatic injuries, iatrogenic injuries, and tumoral bleeding) indicated the effectiveness of RAE, to our knowledge, there have been no previous studies with statistical analyses of the effects on blood pressure (BP) and renal function after RAE [10-17]. The purpose of the present study was to assess the efficacy and safety of RAE in the treatment of traumatic blunt renal injuries, as well as to evaluate its effects on arterial BP and renal function in these patients. MATERIALS AND METHODS All patients who underwent RAE between January 2005 and December 2012 were retrospectively reviewed. All renal injuries were confirmed by contrast-enhanced computed tomography (CT) prior to RAE, and graded based on the AAST system (Table 1) [18]. Indications for RAE were persistent macroscopic hematuria, hemorrhagic shock, and decreased hemoglobin on serial tests after conservative measures. In selected cases with hemodynamic instability, RAE was performed instead of surgical management after discussion with surgeons and urologists. Technique Patients were evaluated with digital subtraction angiography followed by RAE in the same session. During the procedure, arterial access was gained through the femoral artery using a 5-French sheath (Radifocus Introducer II; Terumo). Diagnostic renal angiography was performed using a 4-French hook-shaped catheter (Radifocus Optitorque; Terumo). The entire renal vascular anatomy was assessed and vascular injuries were located. Selective intrarenal angiography was then performed for the evaluation of subsequent embolization. A 2.7-French microcatheter (Progreat; Terumo) was used in selective patients to achieve a stable catheter tip engagement. Whenever possible, RAE was limited to the site of bleeding to minimize parenchymal devascularization. The embolic agent was selected based on the site and size of the lesion. Technical success was defined as complete occlusion of the vascular lesions on completion angiography. Clinical success was defined as complete cessation of bleeding without the need for further procedure, and patient didn t die after initial RAE. When patients were reassessed by ultrasonography or CT, cessation of bleeding was considered if the hematoma did not grow in diameter. In the absence of follow-up imagine study, bleeding was considered to have ceased when the BP and hematocrit level became stabilized without the need for blood transfusion. The indications for follow-up using US after RAE were persistent flank pain, routine follow-up of parenchymal injury, urinoma and hematoma. The indications for follow-up using CT after RAE were persistent gross hematuria, decreased urine output, infection, falling of BP and hematocrit level, and to clarify equivocal US findings. All of the follow-up imagines were initially performed during the hospitalization and regularly follow up until 12 months. Renal function and BP assessment Patients who died were excluded from the analysis. If renal function data before the trauma event within 2 years were available, the baseline data were adopted for analysis. The measurements of serum creatinine and BP were obtained at admission, and follow up until 12 months. The renal function was assessed with serum creatinine, estimated glomerular filtration rate [egfr = x (serum creatine ) x (age ) x (0.742 if female); using the Modification of Diet in Renal Disease (MDRD) formula] and classified according to the National Kidney Foundation Stages [19, 20]. The BP was assessed by systolic BP, diastolic BP, estimated mean arterial pressure (MAP, [systolic BP + 2 diastolic BP]/3), and BP stage according to the American Heart Association, in which stages 2 and 3 are considered normal (Table 2) [21]. The last measurement was taken between 4 days and 12 months after RAE to avoid interference due to short-term and long-term variables (e.g., hypovolemic shock, contrast medium-induced nephrotoxicity, stress resulting from symptoms, medication, rehabilitation, and drugs). Patients who could not be followed up within the defined period were not assessed and his/her Table 1. Grading of renal injury based on the AAST Grade Type of injury Description of injury I II III IV V Contusion Hematoma Hematoma Laceration Laceration Laceration Vascular Laceration Vascular Hematuria, urologic studies normal Subcapsular hematoma, without parenchymal laceration Perirenal hematoma, without parenchymal laceration <1.0 cm laceration, without urinary extravasation >1.0 cm laceration, without urinary extravasation Laceration extends to renal pelvis, or urinary extravasation Main renal artery or vein injury with contained hemorrhage Completely shattered kidney Avulsion of renal hilum which devascularizes kidney *American Association of Surgery for Trauma (AAST) system 116 J Radiol Sci December 2015 Vol.40 No.4

3 values would be considered as missing data. Various underlying diseases of the patients were recorded for analysis using multivariate tests. Statistical analysis Univariate analyses (Wilcoxon signed-rank test) were performed to assess whether individual changes occurred in serum creatinine, egfr, renal function stage, systolic BP, diastolic BP, MAP, or BP stage after RAE. Multivariate analyses were used to estimate linear models in which individual differences between egfr, systolic BP, diastolic BP, and MAP before and after RAE were regressed on the following variables: demographic data, hematuria based on urine test, renal trauma grading, angiographic findings, embolic material, and level of embolized renal artery. The missing data of variables were treated with listwise deletion. Dichotomous variables of the age and the number of associated organ injuries in addition to the kidneys were created to investigate how mortality can be predicted by more than one explanatory variable. Binary logistic regression was used to assess the predicted variables for mortality. Odd ratio (OR) was used to quantify how strongly the presence of dichotomous variable and Fisher s exact test was used to evaluate the significance. The Pseudo R-squared Measures (pseudo-r2s) was used to evaluate goodness of fit of the model. The predicted probability of mortality was obtained and then used to calculate the Area under the Receiver Operating Characteristic Curve (AUROC). RESULTS Sixty-four patients who underwent RAE for blunt renal trauma (BRT) between January 2005 and December Table 2. Classification of renal function* and blood pressure** Category Renal function stage Blood pressure stage egfr SBP DBP (ml/min/1.73m2) (mmhg) Stage 1 90 < 90 or < 60 Stage and Stage or Stage or Stage 5 < or Stage or 110 * Renal function stage was classified according to the National Kidney Foundation Stages. ** Classification of blood pressure stage was adopted by the American Heart Association, in which, stages 2 and 3 were considered normal range of BP were included (mean age, 34.6 ± 17; 51 males and 13 female). Table 3 shows a summary of the baseline patient data. Angiography and embolization data Various types of vascular lesions presented as active extravasation of contrast medium, pseudoaneurysm with various sizes, or arteriovenous fistula with various degrees (e.g. early venous return and abnormal venous drainage) (Figure 1, 2 and 3). Vascular contrast medium extravasation (n = 52; 81.3%) was commonly encountered in BRT. Table 3. Baseline characteristics of patients and renal trauma grading Characteristic Demographic Age, year Value 34.6 ± 17(13-82) Sex, male n = 51(79.7%) Causes female 13(20.3%) Motor vehicle accidents (MVA) n = 50(78.1%) Falling down 8(12.5%) Hitting (by fist or chair) 5( 7.8%) Cannot recall reason due to drunk 1( 1.6%) Comorbidities Non-specific medical history n = 51(79.7%) Hypertension (HTN) under treatment 5(7.8%) Diabetes mellitus (DM) 6(9.4%) Chronic kidney disease (CKD) 6(9.4%) ADPKD 2(3.1%) Cerebrovascular accident (CVA) 1(1.6%) Myocardial infarction (MI) 1(1.6%) Renal trauma grading (AAST)* Right (51.6%) Left (48.4%) Grade II 1 n = 1(1.6%) Grade III (26.6%) Grade IV (42.1%) Grade V (30.0%) Values are expressed as: Mean ± Standard Deviation (Range), or Number (Percentage). ADPKD = Autosomal dominant polycystic kidney disease *Renal injuries were graded based on the American Association of Surgery For Trauma (AAST) system, which is according to depth of damage and involvement of the urinary collecting system and renal vessels. In this study, it is done based on CT finding before angioembolization. J Radiol Sci December 2015 Vol.40 No.4 117

4 However, pseudoaneurysm and arteriovenous fistula (AVF) were not particularly rare and were usually associated with vascular contrast medium extravasation. Of 26 cases of pseudoaneurysm in this series, 11 were isolated pseudoaneurysm, 13 were associated with contrast extravasation, one was associated with AV fistula, and one was associated with both contrast extravasation and AV fistula. Of five cases of AV fistula, they were associated with contrast extravasation (n = 3), pseudoaneurysm (n = 1), and both (n = 1). In the majority of patients with BRT, the coil/microcoil was used as the first-choice embolizer (n = 39; 60.9%); other embolizers are listed in Table 4. Microcatheters were used in 43 cases (67.2%) for superselective catheterization and embolization. The segmental artery was the most frequent site for RAE (n = 48; 75%). Technical success was achieved in 62 cases (96.9%). Two technical failures occurred in patients with multiple trauma. In these two cases, diagnostic angiography showed extravasation from the proximal main trunk. Despite RAE with coils was performed, the bleeder at main renal artery was incompletely occluded and therefore the treatment was converted to surgical management. Clinical outcomes Clinical success was achieved in 55 patients (n = 55; 85.9%). Six patients who underwent RAE for BRT died during hospitalization (n = 6; mortality rate=9.4%) (Table 3). Older age ( 60 years) and multiple organ injuries ( 2 in addition to the kidneys) were significant risk factors for mortality (OR = 10.1, 95% confidence interval, CI = , p = 0.023; OR = 8.7, 95% CI = , p = 0.015, Figure 1 respectively). The value of pseudo-r2s was The value of AUROC was indicating that the model has excellent accuracy. Of the 64 patients of BRT managed with RAE, 44 (68.8%) had renal-related complications: hematuria (n = 42; 65.6%), urinoma (n = 6; 9.4%), urinary tract infection (n = 3; 4.7%), bladder tamponade (n = 2; 3.1%), hydronephrosis (n = 4; 6.3%), and perirenal abscess (n = 3; 4.9%). Almost all of the complications were resolved after conservative treatment (n = 37, 84.1%), except the 4 cases of hydronephrosis and 3 cases of perirenal abscess that required further intervention. Effects on renal function The effects of RAE on renal function could not be Table 4. Characteristics of angiographic procedure and post-procedure outcome Characteristic Angiographic finding Value Active extravasation n = 52 Pseudoaneurysm 26 Arteriovenous fistula 5 Embolic Material Gelfoam particle n = 14(21.9%) Coil/Microcoil 39(60.9%) Gelfoam + Coil/Microcoil 11(17.2%) NBCA n = 0 Level of embolized renal artery Right Left Both Main trunk 6 3 n = 9(14.1%) Segmental (75%) Interlobar 4 1 5(7.8%) Capsular artery 1 1 2(3.1%) Outcome Technical success* n = 62(96.9%) Clinical success** 55(85.9%) Mortality 6(9.4%) Figure 1. Various type of angiographic findings. The majority of angiographic finding was active extravasation of contrast medium (n = 52). Pseudoaneurysm with various sizes (2mm-3cm) and arteriovenous fistula with various degrees (e.g. early venous return and abnormal venous drainage) were revealed in some cases. Hospitalization, day*** 4-74(11/10.25) NBCA = n-butyl cyanoacrylate. * Technical success was defined as complete occlusion of the vascular lesions on completion angiography. ** Clinical success was defined as complete cessation of bleeding without the need for further procedure or death after initial RAE. *** Hospitalization is expressed as: Range (Median/Interquartile Range, IQR). 118 J Radiol Sci December 2015 Vol.40 No.4

5 Figure 2 2a 2c 2b 2d 2e Figure 2. A 19-year-old female was diagnosed with Grade IV renal injury (AAST). (a) (b) Fluid collection of mixed density is distributed in the perirenal space, low density fluid (10-15HU on non-enhanced CT) is seen along the renal pelvis to perirenal space, which is in favor of perirenal hematoma mixing with urinoma (asterisk). (c) Enhanced (d) coronal reconstruction CT showed at least two lacerations extending to renal pelvis (arrow), and pooling of urinary contrast medium on the delayed phase scan. (e) The digital subtraction angiography (DSA) showed a pseudoaneurysm and extravasation of contrast medium. The main renal artery was intact. Figure 3 3a 3b 3c Figure 3. A 21-year-old male was diagnosed with Grade V renal injury (AAST). (a) (b) CT scan showed a shattered kidney with pooling of contrast medium. (c) The following DSA showed small pseudoaneurysms (arrow) and extravasation of contrast medium at delayed phase. The main renal artery was intact. J Radiol Sci December 2015 Vol.40 No.4 119

6 assessed in 13 patients. Among them, six had missing values in follow-up study and 7 (including one with preexisting end-stage renal disease) died during hospitalization. The effects of RAE on renal function were analyzed in 52 patients (89.7%; 42 males, 10 females) with a mean age of 33.4±16.2 (range, 13 82) years. The follow-up egfrs were recorded (median / IQR, 46.5 / 185.5) days after RAE. The mean creatinine values before and after RAE were 1.24 ± 0.79 and 0.93 ± 0.41 mg/dl, respectively. The mean egfr values before and after RAE were ± and ± ml/min/1.73 m2, respectively. The mean renal function stage values before and after RAE were 2.00 ± 0.89 and 1.52 ± 0.70, respectively; 26 patients (44.8%) had unchanged renal function stage, 24 patients (41.4%) had improved renal function stage, and two (3.4%) had declined renal function stage. Wilcoxon test revealed significant improvement in serum creatinine, egfr and renal function stage (p < 0.001) before versus after RAE. Multivariate predictive modeling of scores after RAE showed no independent predictor of egfr or renal function stage after RAE. Fifteen patients had previous renal function records before the event of trauma, and the effects of trauma and RAE on renal function could not be assessed in three of these patients: two had missing values in follow-up study and one died during hospitalization. The effects of RAE on renal function were analyzed in 12 patients (9 males and 3 females) with a mean age of ± (range, 19 82) years. Previous renal function data were recorded within 2 years before the event of BRT. Wilcoxon test revealed no significant difference in serum creatinine, egfr and Figure 4 4a 4b 4c Figure 4. Effects of RAE on renal function. A box plot: median, interquartile range (IQR), adjusted range within 1.5 IQR, outliers depicted as small o and extreme values depicted as *". (a-c) The follow-up egfrs were assessed (median/ IQR, 46.5/185.5) days after RAE, which showed significant improvement in serum creatinine, egfr and renal function of after RAE verse before RAE (p < 0.001). No significant difference in serum creatinine, egfr and renal function stage before trauma versus after RAE (p = 0.358, and 0.102). 120 J Radiol Sci December 2015 Vol.40 No.4

7 renal function stage before trauma versus after RAE (p = 0.358, and 0.102). Figure 4 summarizes the changes in renal function analysis before trauma, before RAE and after RAE. Effects on blood pressure The effects of RAE on BP were analyzed in 58 patients (46 males and 12 females, with a mean age of ± years; range, years). The follow-up BP was recorded (median / IQR, 12 / 21.5) days after RAE. Wilcoxon test revealed significant increases in diastolic BP (70.81 ± mmhg vs ± 9.97 mmhg, p = 0.017) and MAP (87.49 ± mmhg vs ± 8.65 mmhg, p = 0.018) before RAE versus after RAE, but no significant differences in systolic BP ( ± mmhg vs ± mmhg, p = 0.116) or BP stage (2.64 ± 1.33 vs 2.84 ± 0.59, p = 0.236). The number of patients with normal BP (stage 2 and 3) before and after RAE were 30(51.7%) and 52(89.7%), and the improvement was significant (p < 0.001). Multivariate predictive modeling of scores identified no independent predictors of systolic BP, diastolic BP, MBP, or BP stage after RAE. Figure 5 summarizes the changes in blood pressure analysis before RAE and after RAE. DISCUSSION Transcatheter arterial embolization has been used extensively as a means of nonoperative management for cessation of hemorrhage in hemodynamically stable Figure 5 5a 5b 5c 5d Figure 5. Effects of RAE on blood pressure. (a-c) The follow-up BP was assessed (median/iqr, 12/21.5) days after RAE, which showed significant increases in diastolic BP (p = 0.017) and MAP (p = 0.018) before RAE versus after RAE, but no significant differences in systolic BP (p = 0.116) or BP stage (p = 0.236). (d) No patient had hypotension (stage 1) and the number of patients with normal BP (stages 2 and 3) was significantly increased after RAE (p < 0.001). J Radiol Sci December 2015 Vol.40 No.4 121

8 Table 5. Published series on percutaneous embolization for blunt renal trauma Study, Year Type of renal injury No. of pts. Technical success (%) Clinical success (%) Effects on renal function Effects on blood pressure Hagiwara et al, 2001 blunt trauma 8 88 NSM NSM NSM Poulakis, 2006 blunt trauma, iatrogenic no difference; NSS NSM Kitase et al, 2007 blunt trauma NSM NSM Breyer et al, 2008 iatrogenic, tumor rupture, blunt and penetrating trauma NSM NSM Brewer et al, 2009 blunt trauma ; NSS NSM Stewart et al, 2010 blunt trauma ; NSS Huber et al, 2011 iatrogenic, blunt and penetrating trauma newly diagnosed HTN in 1 pt ; NSS NSM van der Wilden et al, blunt trauma 154 NSM 92 NSM NSM 2013 NSM = no specific mention, NSS = no statistical analysis patients without evidence of hollow viscus injury and more recently for selected unstable patients [22]. The feasibility and safety of RAE for renal trauma have been described in several studies consisting of a small number of patients, mixed populations, and these studies lack analysis of the effects of RAE on renal function and BP [10-17]. The previously reported case series associated with RAE for renal trauma are summarized in Table 4. Many studies measured serum creatinine level to assess renal function instead of applying the egfr, as in the present study. Previous study including patients with iatrogenic renal injury had set the including duration «between 5 days and 12 months after RAE» [8]. Our study used the modified duration «between 5 days and 12 months after RAE» because the majority of the patients in the study visited the emergency room (ER) without medical comorbidity and discharged more early than the patients with complicated comorbidities in other studies. In the present study, there was significant improvement in renal function after RAE versus that before RAE, but no significant difference versus that before trauma. The percentage of patients with renal function stage 1 (egfr 90 ml/min/1.73 m2) before RAE versus after RAE were 30.8% (n = 20/65) and 57.7% (n = 30/52), respectively, indicating that more than half of the patients with severe BRT (AAST grading: 29% grade V, 42% grade IV, 27% grade III, and 2% grade II) had their renal function restored after RAE. Vascular injuries in BRT could deteriorate renal function (e.g., hematoma mass effects on renal parenchyma and urinary tract, and decreased effective blood flow to the kidneys because of active bleeding) and selective RAE would obliterate vascular lesions and achieve adequate preservation of renal function. Several studies used a variety of methods (e.g., dynamic scintigraphy, estimated parenchymal loss based on completion angiography or follow-up CT) to evaluate the effects of RAE on the kidneys [11, 23, 24,]. Although the results of most studies showed a small area of renal infarction after embolization, no significant loss of renal function was identified based on creatinine levels [11, 23, 24]. There were significant increases in diastolic BP and MAP after RAE, but no significant differences in systolic BP. Although there was no significant difference in BP stage before versus after RAE, there was no patient with hypotension (stage 1) and the number of patients with normal BP (stages 2 and 3) was significantly increased after RAE (p < 0.001). In the present study, segmental arterial embolization was recommended rather than subsegmental embolization (for interlobar artery or more distal branches) in patients with severe BRT because of increased procedure duration, risk of recurrent bleeding, and lack of significant benefits in renal function and BP. A previous study indicated that subsegmental embolization in patients with iatrogenic renal injury had a lower infarcted kidney area; however, there were no significant differences in serum creatinine levels [11]. Moreover, subsegmental embolization may cause recurrent bleeding at other parts of the same segment from vascular injuries that are initially compressed by adjacent hematoma. This tamponade effect may gradually dissolve over time. Therefore, prophylactic embolization of an area greater than the angiographic lesion is likely necessary in trauma cases, especially those with large perirenal hematomas. Use of a microcatheter was recommended for precise catheterization and embolization if the renal arteries were tortuous or small. Many reports have presented detailed discussion of the 122 J Radiol Sci December 2015 Vol.40 No.4

9 characteristics of the various embolizers used in RAE [25]. However, few studies have employed statistical methods for the analysis of embolizers, and the results are controversial. The general goal of RAE is to occlude the branch with vascular lesion and spare surrounding branches to limit parenchymal damage. In the present study, we used the coil/ microcoil as the first choice of embolizer for RAE because excluding the diseased area while preserving irrigation of the downstream vascular bed was possible. In the study, 9 patients were performed RAE at main renal artery. The indications for embolization of main renal artery were active bleeding from main renal artery, pseudoaneurysm arising from main renal artery and difficult catheterization to segmental artery. All of the cases were discussed with the patients families and surgeons before RAE. All of them reached technical success. Two technical failures occurred in patients with active bleeding from the proximal main trunk of renal artery. Despite RAE was performed with coils, the bleeder at main renal artery was too proximal to be completely occluded. Because of high risk of endovascular treatment, the treatment was converted to surgical management. No patient with BRT underwent renal artery stent placement in the study. In our experience, emergent procedure of endovascular stent in patients with severe blunt renal trauma is not recommended because of the following reasons: renal artery stenting in agitated and uncooperative patients at emergency setting may lead to severe complication; the stent of appropriate size may be not available at emergency time especially in the midnight; the cost of the procedure is very expensive. Six patients with BRT died after embolization (mortality rate = 9.4%). The odds of patients with older age ( 60 years) or multiple organ injuries ( 2 in addition to the kidneys) who underwent RAE for BRT were ten times and nine times the odds of young age (< 60 years) or not multiple organ injuries (< 2 in addition to the kidneys) to proceed to a life-threatening condition. The dichotomous variables of age, number of injured organs in addition to kidney and other variables were come out after observation of collecting data. We took many trials of statistical analysis and got the best conclusion of variables and cut points. Bauer et al. have reported the potential complications of arterial embolization in trauma patients, such as contrast reactions, vascular injury, non-target embolization, migration of coils, post-embolization infections, and postembolization syndrome (pain, leukocytosis, and pyrexia); the greatest threat was non-target embolization [26]. In the present study, 44 patients (68.8%) had renal-related complications. Most of the complications were caused by the trauma itself (e.g., urinoma, hematuria, bladder tamponade, and hydronephrosis). In total, 89.1% of the renal-related complications were resolved after conservative treatment. A recent study comparing surgical and nonsurgical treatment of grade V injuries indicated a better outcome with conservative management [27]. Our data showed that RAE for BRT offers a rapid, precise, and effective management with excellent tissue preservation. RAE is sufficient in the treatment of vascular complications of renal injury with pseudoaneurysm, active bleeding, or AV fistula. Our study had several limitations and biases. First, it is one-trauma-center-study which may exist referral bias in the samples. Second, our sample cohort was relatively small and the follow-up period was relatively short. Third, many patients with good response to RAE were excluded from the statistical analysis due to early discharge and insufficient follow-up. Moreover, our retrospective method could have underestimated the minor RAE-associated renal complications such as regional renal infarction. CONCLUSIONS RAE for patients with severe BRT in need of further intervention has high technical and clinical success rates. Successful and appropriate RAE can preserve renal function and restore normal BP after the procedure, even for selected patients with hemodynamic instability. Although some patients may develop renal-related complications, most would be resolved after conservative treatment. ACKNOWLEDGEMENTS We want to thank Ms. Hsiao-Ting Juang for statistical consultation, who was supported by grants from Biostatistical Center for Clinical Research, Chang Gung Memorial Hospital (CLRPG340599). REFERENCES 1. McAninch JW, Carroll PR, Klosterman PW, Dixon CM, Greenblatt MN. Renal reconstruction after injury. J Urol 1991; 145: Miller KS, McAninch JW. Radiographic assessment of renal trauma: our 15-year experience. 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