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Published online before print May 3, 2002, 10.1148/radiol.2233011216
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(Radiology 2002;223:723-730.)
© RSNA, 2002

Vascular and Interventional Radiology

Blunt Renal Trauma: Minimally Invasive Management with Microcatheter Embolization—Experience in Nine Patients1

Hans-Peter Dinkel, MD, Hansjörg Danuser, MD and Jürgen Triller, MD

1 From the Departments of Diagnostic Radiology (H.P.D., J.T.) and Urology (H.D.), University of Bern, Inselspital, Freiburgstrasse 20, CH 3010 Bern, Switzerland. Received July 18, 2001; revision requested September 11; revision received October 24; accepted November 13. Address correspondence to H.P.D. (e-mail: hans-peter.dinkel@insel.ch).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
PURPOSE: To evaluate superselective embolization therapy for the management of arterial damage in patients with severe renal trauma.

MATERIALS AND METHODS: Nine consecutive patients with renovascular injuries after blunt trauma underwent superselective embolization. Six patients had pseudoaneurysms or traumatic arteriovenous fistulas. Three patients had frank, uncontained extravasation (two shattered kidneys, one complete pedicle avulsion) and were treated immediately after admission. Two patients were hemodynamically unstable. All patients underwent embolization with 3-F coaxial microcatheters and polyvinyl alcohol particles (n = 2) or 0.018-inch platinum microcoils (n = 7). Procedural and medical success and complications (eg, postembolization syndrome, abscess, permanent serum creatinine elevation, hypertension) were retrospectively assessed from the patients’ records. Mean clinical follow-up was 11.9 months (range, 1–50 months).

RESULTS: In all cases bleeding was effectively controlled with superselective embolization in a single session. There was no procedure-related loss of renal tissue in eight cases; in one patient, a lower pole remnant of 20% of viable ipsilateral parenchyma was lost due to the procedure. In one patient, a coil migrated into a lumbar artery without causing clinical consequences. None of the patients developed abscess, hypertension, or procedure-related impairment of renal function.

CONCLUSION: Superselective embolization may be used for effective, minimally invasive control of active renovascular bleeding.

© RSNA, 2002

Index terms: Arteries, therapeutic embolization, 96.1264 • Kidney, injuries, 81.41, 81.48 • Kidney, interventional procedures, 81.1264


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
The consequences of blunt renal trauma range from simple contusion or renal hematoma to complete shattering of the organ or avulsion of the vascular pedicle (1,2). In the vast majority of cases, renal injuries are minor and self-limiting (3). Conservative (expectant) treatment is increasingly accepted as the preferred approach to most renal injuries (1,4–8). In the presence of massive hemorrhage or continuous hematuria in patients with trauma-induced pseudoaneurysm or fistula, aggressive therapy may become necessary. Accepted indications for surgery are avulsion of the renal pelvis, injuries to the vascular pedicle, and life-threatening hemodynamic instability (1). Vascular injury can also be effectively treated with angiographic procedures; superselective renal embolization has been reported to be effective in the treatment of iatrogenic and penetrating vascular kidney injuries (9,10). While endovascular therapy seems to be well established in the treatment of penetrating and iatrogenic renal injuries, less attention has been paid to the role of superselective embolization in the treatment of noniatrogenic and blunt renal trauma.

The purpose of our study was to evaluate superselective embolization therapy for the management of arterial damage in patients with severe renal trauma.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
DISCUSSION
 REFERENCES
 
We manually searched the archives of our angiography suite to identify all patients who had undergone superselective renal embolization for blunt renal trauma at our interventional radiology department between July 1985 and June 2001. All patients were examined and treated as part of routine care and gave informed consent. Our institutional review board did not require its approval or informed consent for this study.

Diagnostic staging was performed according to the criteria of the American Association for the Surgery of Trauma (11,12) (Table 1). As is the case in many other centers, the vast majority of our patients with renal trauma were treated without intervention because most renal trauma (in 90% of cases or more) is minor (grade I, contusion) and requires no treatment at all (8). Of 71 patients with more severe renal trauma (grades II–V), 44 were cared for conservatively and 18 underwent surgery. The remaining nine patients, who had severe renal trauma (grades III–V) with vascular complications, were treated with interventional radiologic techniques. In 1989, the management policy at our institution was changed to favor conservative treatment instead of renal surgery (8).


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  		TABLE 1. Organ Injury Scale for Blunt Renal Trauma from the American Association for the Surgery of Trauma

 
The following diagnostic modalities were used for evaluating the patients: sonography, intravenous urography, and contrast material–enhanced computed tomography (CT) (the current standard diagnostic modality [13]), as well as arterial angiography. Sonograms were negative in patient 1 but revealed retroperitoneal hematoma or renal laceration in all other patients. Intravenous urography was performed in patients 1–5 and 9, and the resulting images were positive for pelvic filling defects in all. CT was performed in patients 2–9 and was most useful in revealing both renal pelvic and perirenal abnormalities. Angiography was performed in every patient and demonstrated renovascular injury in all nine. Clinical follow-up ranged between 1 and 50 months (mean, 11.9 months). All patients underwent follow-up imaging with ultrasonography (US) and CT.

Patient Characteristics
Substantial hematuria following flank trauma was the leading symptom in all patients; all had experienced considerable renal blood loss requiring blood substitution. Eight patients did not undergo renal surgery before or after embolization, while one underwent embolization 3 months after sustaining a gunshot injury that was initially treated with immediate exploratory surgery at another institution.

Six patients with persistent or recurrent severe hematuria underwent embolization secondarily, after a delay ranging from 5 days to 3 years from the date of the initial trauma. These patients had developed traumatic renal pseudoaneurysms; three patients also had concomitant traumatic arteriovenous fistulas (AVFs). One patient had three pseudoaneurysms.

Three other patients had frank, uncontained active bleeding without pseudoaneurysm and were treated within hours after the trauma. All three patients had grade V injuries (two had shattered kidneys, one had vascular pedicle avulsion). Two of these patients were hemodynamically unstable.

Embolization Technique
Selective renal digital subtraction angiography was performed transfemorally with a 5-F cobra catheter. After the source of the bleeding was identified and during the same session, the catheter was maneuvered into a more distal position with a steerable 0.035-inch guide wire (Radiofocus; Terumo, Tokyo, Japan). Next, a 3-F superselective coaxial catheter (Target 18; Boston Scientific/Target Therapeutics, Natick, Mass) was introduced coaxially in proximity to the bleeding branch.

Microcoils of 0.018 inch in diameter (Target VortX coils; Boston Scientific/Target Therapeutics) with a nominal configured diameter of 2 x 3 mm to 2 x 4 mm and a length of 6 cm were used for embolization in seven patients, while polyvinyl alcohol (PVA) particles (Contour; Boston Scientific) (250–350 µm) were used for embolization in two patients. In patient 3, a 14-mm x 30-cm Guglielmi detachable coil (Target; Boston Scientific/Target Therapeutics) was used to fill the sac of a renal pseudoaneurysm that was combined with an AVF to prevent coil migration into the venous system prior to the application of smaller VortX coils. In this patient the feeder artery was very short, which impeded isolated embolization of the feeder. All embolization procedures were performed by three interventional radiologists (including H.P.D. and J.T.) who had 3–15 years of experience with intraarterial catheter embolization techniques. Although two interventional radiologists used coils for embolization in all cases, the third used PVA particles for embolization on the basis of personal preference.

Data Evaluation, Criteria for Success, and Complications
Radiologic records and patient charts were reviewed by two authors (H.P.D. and J.T.) together to extract information about the technical success of the procedure, medical success of the procedure, and technical and medical complications. Technical success of the procedure was defined as complete occlusion of all renovascular bleeding with arterial embolization as documented with arterial angiography at the end of the procedure. Medical success was defined by the disappearance of gross hematuria 3 days after embolization at the latest, absence of recurrent hematuria, absence of recurrent need for erythrocyte administration, absence of recurrent decrease of hemoglobin by more than 1.5 g/dL (15 g/L), and absence of need for angiographic reembolization or subsequent renal surgery.

Technical complications included unwanted embolization of vascular territories, iatrogenic vascular damage, and puncture-site bleeding. Medical complications were classified as short term (ie, occurring within 30 days after the intervention) or delayed (ie, occurring 30 or more days after the intervention). Short-term complications included postembolization syndrome (ie, back pain and fever not otherwise accounted for), decrease in renal function (defined as serum creatinine levels > 130 µmol/L), and arterial hypertension (defined as systolic arterial pressure > 160 mm Hg and diastolic pressure > 90 mm Hg). Fever was defined as a body temperature higher than 38.5°C. Delayed complications included decrease in or loss of renal function, perirenal abscess or renal abscess, and arterial hypertension.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Embolization Results and Side Effects
Complete control of active bleeding was achieved in all patients. Patient details and outcomes are shown in Table 2. In six patients who had pseudoaneurysm or AVF, a single subsegmental branch or several subsegmental branches were occluded with two to 10 microcoils (median, four). Examples of clinical presentation and the embolization technique are provided in Figures 1–4. One patient had an avulsed main renal artery that was successfully occluded with microcoils (Fig 3). A microcoil dislodged into a lumbar artery in this patient because of the instability of the catheter in the 2-cm-long stump of the renal artery, but no clinical consequences ensued. PVA particles (250–350 µm) were used in two patients, one of whom had a shattered kidney and required occlusion of two segmental arteries. No loss of viable renal tissue occurred as consequence of the interventional procedure in eight cases. Moderate tissue loss was observed in a patient with a shattered kidney, who retained a remnant of about 20% of ipsilateral tissue. In this patient, two large, central, segmental arteries had ruptured very proximally and were occluded with microcoils. During the intervention, the stretched, elongated artery that supplied the lower pole narrowed, possibly because of intimal injury; this finally led to occlusion, retrograde thrombosis, and loss of the lower pole. Except for the patients with multiple injuries who arrived in the angiography suite intubated, no patient required anesthesia, and none complained of pain related to the embolization procedure.


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  		TABLE 2. Type and Origin of Trauma, Symptoms, and Outcome of Nine Consecutive Patients Treated with Microcatheter Embolization for Noniatrogenic Renal Trauma

 


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  		Figure 1a. Patient 5. A 20-year-old man with grade III renal laceration sustained during a fall on a curbstone underwent therapeutic embolization with microcoils. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization depicts a pseudoaneurysm (black arrow) in the ventral upper third of the left kidney, as well as a large perirenal hematoma (white arrows). (b) Transverse CT scan obtained 3 months after embolization. There is only a small renal scar (short arrow); most of the hematoma has resolved. Note the streak artifact caused by the presence of metallic coils (long arrows). (c) Selective angiogram obtained in an anteroposterior projection after the successful embolization with microcoils of two upper-pole feeder vessels (arrows) of the pseudoaneurysm.

 


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  		Figure 1b. Patient 5. A 20-year-old man with grade III renal laceration sustained during a fall on a curbstone underwent therapeutic embolization with microcoils. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization depicts a pseudoaneurysm (black arrow) in the ventral upper third of the left kidney, as well as a large perirenal hematoma (white arrows). (b) Transverse CT scan obtained 3 months after embolization. There is only a small renal scar (short arrow); most of the hematoma has resolved. Note the streak artifact caused by the presence of metallic coils (long arrows). (c) Selective angiogram obtained in an anteroposterior projection after the successful embolization with microcoils of two upper-pole feeder vessels (arrows) of the pseudoaneurysm.

 


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  		Figure 1c. Patient 5. A 20-year-old man with grade III renal laceration sustained during a fall on a curbstone underwent therapeutic embolization with microcoils. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization depicts a pseudoaneurysm (black arrow) in the ventral upper third of the left kidney, as well as a large perirenal hematoma (white arrows). (b) Transverse CT scan obtained 3 months after embolization. There is only a small renal scar (short arrow); most of the hematoma has resolved. Note the streak artifact caused by the presence of metallic coils (long arrows). (c) Selective angiogram obtained in an anteroposterior projection after the successful embolization with microcoils of two upper-pole feeder vessels (arrows) of the pseudoaneurysm.

 


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  		Figure 2a. Patient 9. A 32-year-old man with bladder tamponade secondary to massive hematuria after laceration of the kidney. The patient had fallen 1 m onto the top of a wall, hitting his right flank. He was treated with microcoil embolization. (a) Selective angiogram obtained in an anteroposterior projection by using a cobra catheter 8 days after the trauma shows three traumatic aneurysms (arrows) in the lower pole of the right kidney. (b) Superselective angiogram obtained in an anteroposterior projection by using a 3-F microcatheter that was positioned proximal to the bifurcation of two of the bleeding branches. Three microcoils (arrows) have been deployed and have already led to complete occlusion of the first pseudoaneurysm and partial occlusion of the second. (c) Angiogram obtained in an anteroposterior projection by using the cobra catheter, which is in a superselective position in the lower branch of the renal artery, shows the progressive occlusion of two lesions, while a third lesion (arrow) is still patent. (d) Selective angiogram obtained in an anteroposterior projection at the conclusion of the intervention shows complete occlusion of all three lesions. There is no loss of parenchyma within the kidney except for a limited vascular territory of subsegmental branches that was occluded as a result of coil embolization.

 


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  		Figure 2b. Patient 9. A 32-year-old man with bladder tamponade secondary to massive hematuria after laceration of the kidney. The patient had fallen 1 m onto the top of a wall, hitting his right flank. He was treated with microcoil embolization. (a) Selective angiogram obtained in an anteroposterior projection by using a cobra catheter 8 days after the trauma shows three traumatic aneurysms (arrows) in the lower pole of the right kidney. (b) Superselective angiogram obtained in an anteroposterior projection by using a 3-F microcatheter that was positioned proximal to the bifurcation of two of the bleeding branches. Three microcoils (arrows) have been deployed and have already led to complete occlusion of the first pseudoaneurysm and partial occlusion of the second. (c) Angiogram obtained in an anteroposterior projection by using the cobra catheter, which is in a superselective position in the lower branch of the renal artery, shows the progressive occlusion of two lesions, while a third lesion (arrow) is still patent. (d) Selective angiogram obtained in an anteroposterior projection at the conclusion of the intervention shows complete occlusion of all three lesions. There is no loss of parenchyma within the kidney except for a limited vascular territory of subsegmental branches that was occluded as a result of coil embolization.

 


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  		Figure 2c. Patient 9. A 32-year-old man with bladder tamponade secondary to massive hematuria after laceration of the kidney. The patient had fallen 1 m onto the top of a wall, hitting his right flank. He was treated with microcoil embolization. (a) Selective angiogram obtained in an anteroposterior projection by using a cobra catheter 8 days after the trauma shows three traumatic aneurysms (arrows) in the lower pole of the right kidney. (b) Superselective angiogram obtained in an anteroposterior projection by using a 3-F microcatheter that was positioned proximal to the bifurcation of two of the bleeding branches. Three microcoils (arrows) have been deployed and have already led to complete occlusion of the first pseudoaneurysm and partial occlusion of the second. (c) Angiogram obtained in an anteroposterior projection by using the cobra catheter, which is in a superselective position in the lower branch of the renal artery, shows the progressive occlusion of two lesions, while a third lesion (arrow) is still patent. (d) Selective angiogram obtained in an anteroposterior projection at the conclusion of the intervention shows complete occlusion of all three lesions. There is no loss of parenchyma within the kidney except for a limited vascular territory of subsegmental branches that was occluded as a result of coil embolization.

 


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  		Figure 2d. Patient 9. A 32-year-old man with bladder tamponade secondary to massive hematuria after laceration of the kidney. The patient had fallen 1 m onto the top of a wall, hitting his right flank. He was treated with microcoil embolization. (a) Selective angiogram obtained in an anteroposterior projection by using a cobra catheter 8 days after the trauma shows three traumatic aneurysms (arrows) in the lower pole of the right kidney. (b) Superselective angiogram obtained in an anteroposterior projection by using a 3-F microcatheter that was positioned proximal to the bifurcation of two of the bleeding branches. Three microcoils (arrows) have been deployed and have already led to complete occlusion of the first pseudoaneurysm and partial occlusion of the second. (c) Angiogram obtained in an anteroposterior projection by using the cobra catheter, which is in a superselective position in the lower branch of the renal artery, shows the progressive occlusion of two lesions, while a third lesion (arrow) is still patent. (d) Selective angiogram obtained in an anteroposterior projection at the conclusion of the intervention shows complete occlusion of all three lesions. There is no loss of parenchyma within the kidney except for a limited vascular territory of subsegmental branches that was occluded as a result of coil embolization.

 


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  		Figure 3a. Patient 6. A 22-year-old man who underwent coil embolization for grade V vascular pedicle avulsion. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization reveals a huge retroperitoneal hematoma (arrowheads) and complete transection of the right renal artery (long straight arrow), which is actively bleeding and feeding the hematoma. The short straight arrow indicates the compressed inferior vena cava, and the curved arrow points to a spot of contrast material that represents active extravasation. Note the absence of the left kidney. (b) Nonselective angiogram obtained in an anteroposterior projection after embolization of the stump of the avulsed right renal artery shows the microcoils (arrow). The absence of a left renal artery indicates left-sided renal agenesis.

 


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  		Figure 3b. Patient 6. A 22-year-old man who underwent coil embolization for grade V vascular pedicle avulsion. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization reveals a huge retroperitoneal hematoma (arrowheads) and complete transection of the right renal artery (long straight arrow), which is actively bleeding and feeding the hematoma. The short straight arrow indicates the compressed inferior vena cava, and the curved arrow points to a spot of contrast material that represents active extravasation. Note the absence of the left kidney. (b) Nonselective angiogram obtained in an anteroposterior projection after embolization of the stump of the avulsed right renal artery shows the microcoils (arrow). The absence of a left renal artery indicates left-sided renal agenesis.

 


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  		Figure 4a. Patient 7. A 32-year-old woman who underwent embolization with PVA particles for a grade V renal laceration (shattered kidney) sustained during a motorbike accident. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization shows a viable remnant of tissue (white arrows), arterial extravasation of contrast material (black arrow), and a large hematoma (arrowheads) in and around the shattered left kidney. (b) A nonselective angiogram obtained in an anteroposterior projection shows active extravasation of contrast material (arrow) in the lacerated left kidney. Roughly 20% of viable tissue (arrowheads) remains in the lower part of the left kidney. (c) Radiograph obtained in an anteroposterior projection shows massive extravasation of contrast material in the left perirenal space. (d) Selective angiogram obtained in an anteroposterior projection after embolization with PVA particles demonstrates occlusion of the previously bleeding branches but preservation of the viable tissue remnants (arrowheads). (e) Delayed-phase CT scan obtained 1 week after embolization depicts the viable lower pole and demonstrates that the residual renal tissue (thin arrows) is functioning in that it is excreting contrast material. However, a small urinoma (thick arrow), which was not opacified on the unenhanced scan or during the portal venous phase, is present near the posterior aspect of the left kidney.

 


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  		Figure 4b. Patient 7. A 32-year-old woman who underwent embolization with PVA particles for a grade V renal laceration (shattered kidney) sustained during a motorbike accident. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization shows a viable remnant of tissue (white arrows), arterial extravasation of contrast material (black arrow), and a large hematoma (arrowheads) in and around the shattered left kidney. (b) A nonselective angiogram obtained in an anteroposterior projection shows active extravasation of contrast material (arrow) in the lacerated left kidney. Roughly 20% of viable tissue (arrowheads) remains in the lower part of the left kidney. (c) Radiograph obtained in an anteroposterior projection shows massive extravasation of contrast material in the left perirenal space. (d) Selective angiogram obtained in an anteroposterior projection after embolization with PVA particles demonstrates occlusion of the previously bleeding branches but preservation of the viable tissue remnants (arrowheads). (e) Delayed-phase CT scan obtained 1 week after embolization depicts the viable lower pole and demonstrates that the residual renal tissue (thin arrows) is functioning in that it is excreting contrast material. However, a small urinoma (thick arrow), which was not opacified on the unenhanced scan or during the portal venous phase, is present near the posterior aspect of the left kidney.

 


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  		Figure 4c. Patient 7. A 32-year-old woman who underwent embolization with PVA particles for a grade V renal laceration (shattered kidney) sustained during a motorbike accident. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization shows a viable remnant of tissue (white arrows), arterial extravasation of contrast material (black arrow), and a large hematoma (arrowheads) in and around the shattered left kidney. (b) A nonselective angiogram obtained in an anteroposterior projection shows active extravasation of contrast material (arrow) in the lacerated left kidney. Roughly 20% of viable tissue (arrowheads) remains in the lower part of the left kidney. (c) Radiograph obtained in an anteroposterior projection shows massive extravasation of contrast material in the left perirenal space. (d) Selective angiogram obtained in an anteroposterior projection after embolization with PVA particles demonstrates occlusion of the previously bleeding branches but preservation of the viable tissue remnants (arrowheads). (e) Delayed-phase CT scan obtained 1 week after embolization depicts the viable lower pole and demonstrates that the residual renal tissue (thin arrows) is functioning in that it is excreting contrast material. However, a small urinoma (thick arrow), which was not opacified on the unenhanced scan or during the portal venous phase, is present near the posterior aspect of the left kidney.

 


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  		Figure 4d. Patient 7. A 32-year-old woman who underwent embolization with PVA particles for a grade V renal laceration (shattered kidney) sustained during a motorbike accident. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization shows a viable remnant of tissue (white arrows), arterial extravasation of contrast material (black arrow), and a large hematoma (arrowheads) in and around the shattered left kidney. (b) A nonselective angiogram obtained in an anteroposterior projection shows active extravasation of contrast material (arrow) in the lacerated left kidney. Roughly 20% of viable tissue (arrowheads) remains in the lower part of the left kidney. (c) Radiograph obtained in an anteroposterior projection shows massive extravasation of contrast material in the left perirenal space. (d) Selective angiogram obtained in an anteroposterior projection after embolization with PVA particles demonstrates occlusion of the previously bleeding branches but preservation of the viable tissue remnants (arrowheads). (e) Delayed-phase CT scan obtained 1 week after embolization depicts the viable lower pole and demonstrates that the residual renal tissue (thin arrows) is functioning in that it is excreting contrast material. However, a small urinoma (thick arrow), which was not opacified on the unenhanced scan or during the portal venous phase, is present near the posterior aspect of the left kidney.

 


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  		Figure 4e. Patient 7. A 32-year-old woman who underwent embolization with PVA particles for a grade V renal laceration (shattered kidney) sustained during a motorbike accident. (a) Transverse contrast-enhanced spiral CT scan obtained before embolization shows a viable remnant of tissue (white arrows), arterial extravasation of contrast material (black arrow), and a large hematoma (arrowheads) in and around the shattered left kidney. (b) A nonselective angiogram obtained in an anteroposterior projection shows active extravasation of contrast material (arrow) in the lacerated left kidney. Roughly 20% of viable tissue (arrowheads) remains in the lower part of the left kidney. (c) Radiograph obtained in an anteroposterior projection shows massive extravasation of contrast material in the left perirenal space. (d) Selective angiogram obtained in an anteroposterior projection after embolization with PVA particles demonstrates occlusion of the previously bleeding branches but preservation of the viable tissue remnants (arrowheads). (e) Delayed-phase CT scan obtained 1 week after embolization depicts the viable lower pole and demonstrates that the residual renal tissue (thin arrows) is functioning in that it is excreting contrast material. However, a small urinoma (thick arrow), which was not opacified on the unenhanced scan or during the portal venous phase, is present near the posterior aspect of the left kidney.

 
Clinical Results and Complications
In all patients, bleeding was immediately controlled with the embolization procedure. All patients were treated in a single interventional session and did not need further intervention, with the exception of one patient who had concomitant pancreatic and bile duct laceration and who underwent surgical exploration and a biliodigestive anastomosis. Urine was clear at macroscopy in all patients within 1–3 days after the procedure. However, a week after embolization, one patient experienced recurrent gross hematuria, which resolved spontaneously. In only one patient did microhematuria persist until the patient was discharged from the hospital. Although there was a transient increase in creatinine levels in one patient, which was possibly due to contrast material nephrotoxicity, all patients had normal renal function at discharge except for the patient with the avulsed single kidney and contralateral renal agenesis; this patient was referred to the chronic dialysis program.

There was no evidence of the so-called postembolization syndrome. However, four patients had fever that was presumably unrelated to the angiographic intervention. These included the three patients who had sustained multiple injuries. One of these three patients had a complicated clinical course, with pancreatitis due to a pancreatic laceration that was combined with bile duct avulsion. The two other patients developed pneumonia and urogenital infection, respectively. One of the patients with pseudoaneurysm had bacteremia, which was possibly caused by retrograde bladder lavage that was performed for bladder tamponade. No patient had renal abscess or infected hematoma. Other than the patient with the pedicle avulsion and the patients with a shattered kidney, our patients experienced no or only minor parenchymal loss. No patient developed abscess, hypertension, or other delayed complications related to renal trauma.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
REFERENCES
 
The vast majority of renal injuries can be managed conservatively (1). Successful management of renal trauma, which ranges from minor contusions (grade I) to shattered kidney and pedicle avulsion (grade V) (12), largely depends on accurate diagnostic staging of the injury and detection of vascular complications (1,4). Contrast-enhanced spiral CT is the best imaging modality for assessing the renal parenchyma, concomitant damage to other structures, and active bleeding (13). It can be combined with single-shot urography performed after CT for assessment of the integrity of the excretory system (8). Surgical intervention is performed in only 5%–10% of renal injuries (11) and continues to decline in frequency with the increasing availability of minimally invasive techniques (6–8). Vascular damage resulting from penetrating and from blunt renal trauma can be treated effectively with superselective catheter embolization. Unlike most authors (9,10,14,15), we treated not only pseudoaneurysms and AVFs but also uncontained renal ruptures, shattered kidneys, and pedicle avulsions. Even in hemodynamically unstable patients with the most severe forms of injury (grade IV and V), surgery can be averted with this technique, which has the potential to enable the salvage of as much viable renal tissue as possible in cases where open revision would often result in total nephrectomy.

Types of Renal Trauma Treated with Catheter Intervention
The majority of renal vascular lesions result from interventional urologic procedures such as percutaneous biopsy, nephrostomy, and lithotripsy. Noniatrogenic renal injury is usually associated with blunt trauma caused by, for example, traffic accidents or falls (2), and it tends to be minor, rarely requiring specific treatment (3). In some countries, however, stab wounds and gunshots from street violence are frequent (9,10,14,15). Severe renal damage may be combined with multiple organ trauma (1,4). A series of reports on the angiographic management of iatrogenic and penetrating renal injuries has unanimously stated that there is a major benefit to superselective catheter therapy, which enabled optimal tissue preservation in the majority of cases (9,16–18). Blunt trauma, however, has been only sporadically treated with embolization, and few authors have described its use in more than half a dozen patients (10,19).

Limitations of Embolization Therapy
Few relevant drawbacks exist for embolization therapy. The services of a well-trained interventional radiologist and an effective team of technicians must be quickly available on a 24-hour basis. However, complications of catheter therapy are relatively rare. Renal artery dissection, which may be a complication of renal catheterization, has been described in up to 7.5% of patients (10). Postembolization syndrome is a form of hyperpyrexia that is known to occur after total renal embolization for tumor ablation (20). It has also been described in patients treated with selective embolization with PVA particles and gelatin sponges and has been attributed to the undesired ablation of renal tissue due to an unexpected reflux of liquid and particulate materials (20), which (unlike platinum coils) may be difficult to control with fluoroscopy. Yet even coils can migrate, as happened in one of our patients in whom backwash of a coil into a lumbar artery occurred without causing clinical consequences. However, because they are easily controlled with fluoroscopy, migrating coils can be retrieved percutaneously. Recently developed devices such as interlocking detachable coils and Guglielmi detachable coils allow for controlled deployment of a coil and its easy retrieval if it is deployed in an unfavorable position. We used Guglielmi detachable coils in one patient who had a very short artery that fed a large AVF. However, these advanced products are up to 10 times as expensive as VortX coils.

Arterial hypertension is a rare complication that is occasionally observed after conservative or surgical treatment; in most cases it resolves spontaneously (1). There is no indication in the literature that the incidence of renal hypertension increases after superselective renal embolization (10,16–18).

Patient Treatment: Surgical versus Nonsurgical Approach
Complex vascular injuries are a potential indication for surgery if there is a fair chance of successful open repair (21). However, injuries like complete vascular pedicle avulsion or blunt renal artery occlusion confer a poor prognosis, even if they are technically amenable to surgery (1,4). This is related to the fact that the critical warm ischemia time for the kidney is little more than 1 hour (22). For logistic reasons it is virtually impossible to achieve complete vascular reconstruction within that time margin. Although organ salvage can be achieved in up to half of cases of surgical revascularization of pedicle injuries (23), postsurgical ipsilateral kidney function has been reported to be limited (24). Of 27 patients with pedicle injuries reported by Cass and Luxenberg (23), three were treated with vascular repair 3–9 hours after trauma, but the ipsilateral kidney function in the two surviving patients was markedly impaired. Similarly, all five cases of attempted surgical repair of complete renal artery occlusions reported by McAninch et al (1) either failed or did not result in a restoration of kidney function. By contrast, a recent study comparing surgical and nonsurgical treatment in grade V injuries indicated a better outcome for conservative management (7). Our data show that superselective embolization for blunt renal trauma offers a rapid, precise, and effective cure with excellent tissue preservation. Catheter embolization is sufficient in the treatment of vascular complications of renal injury with pseudoaneurysm or active bleeding.

Physicians at some institutions perform immediate renal surgical exploration in the treatment of hemodynamically unstable patients because benefits of an aggressive surgical approach have been reported (25). The aggressive approach is being increasingly supplanted by endovascular therapy, which offers immediate and effective control of bleeding as long as an interventional radiology team is at hand. Therapeutic embolization is less invasive than surgery, is likely to reduce morbidity in patients who have sustained multiple injuries, and is likely to maximize the chances of tissue salvage (19).

It has recently been suggested that in pediatric patients with trauma the minimally invasive nature and rapidity of angiographic embolization procedures favor their emergent use in both hemodynamically stable and unstable patients (26).

Unless it affects the main renal vein, retroperitoneal venous bleeding tends to be self-limiting when it is not caused by unreduced open-book pelvic fractures, and most surgeons prefer to treat this kind of bleeding without exploratory surgery. There is even preliminary evidence that lesions of the main renal vein can be effectively treated with interventional techniques such as balloon occlusion (27).

Organ Salvage with Coaxial Catheter Embolization
The rates of organ salvage and tissue preservation have been shown to be excellent when penetrating renal trauma is treated with superselective embolization (9,16–18). Before the advent of the newer coaxial catheters, it was often impossible to catheterize subsegmental branches, and embolization had to be performed more proximally, which resulted in considerable organ damage and loss of function (16). In contrast to the earlier technique of direct catheterization, use of the coaxial technique with microcatheters and microcoils permits precise localization and catheterization of the bleeding arterial branches. Compared with partial or total nephrectomy, coaxial embolization reduces tissue loss because the embolization material can be deployed immediately proximal to the bleeding site; therefore, most of the tissue loss is limited to that caused by the original trauma itself.

Patient Groups Amenable to Endovascular Treatment
A fraction of patients whose condition is initially stable after flank trauma will develop secondary bleeding due to traumatic arterial pseudoaneurysm or AVF. These patients constitute one group of patients with renal trauma that is well suited for angiographic therapy. Like patients with "classic" cases of iatrogenic and penetrating trauma (9,10), these patients typically have delayed presentation with recurrent hematuria after days, weeks, or even months.

A second group of patients was previously treated with immediate surgical exploration. These patients often present as hemodynamically unstable, with active bleeding and leading symptoms of shock and gross hematuria. Circulatory stabilization and avoidance of early surgery in these patients is desirable to reduce morbidity and mortality in the initial period after trauma (28). As described in the previous paragraphs, microcatheter embolization can help to control bleeding without nephrectomy in such patients.

In conclusion, interventional techniques should be increasingly used in actively bleeding renal injuries because they are rapid, effective, tissue preserving, and likely to reduce morbidity and mortality. Even patients with the most severe renovascular lesions and major renal destruction (grades IV and V) can be treated nonsurgically with microcatheter embolization, with an excellent chance that a maximum amount of functional renal parenchyma will be preserved. Randomized prospective multicenter trials are needed to define the exact value of this method; however, these are difficult to design and to perform.


   FOOTNOTES
 
Abbreviations: AVF = arteriovenous fistula, PVA = polyvinyl alcohol

Author contributions: Guarantors of integrity of entire study, H.P.D., J.T.; study concepts, H.P.D., J.T.; study design, H.P.D., J.T., H.D.; literature research, H.P.D., H.D.; clinical studies, J.T., H.P.D., H.D.; data acquisition, J.T., H.P.D.; data analysis/interpretation, H.P.D., J.T.; manuscript preparation, H.P.D.; manuscript definition of intellectual content, H.P.D., J.T.; manuscript editing, revision/review, and final version approval, H.P.D., H.D., J.T.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 

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