Overview The horseshoe kidney is more prone to blunt abdominal trauma because of its low position and the presence of the isthmus across the midline. This is a rare case of complete transection of a horseshoe kidney at the isthmus due to blunt abdominal trauma with two sites of active extravasation on initial CT imaging. This extravasation was successfully treated by embolization with coils. Superselective embolization may be used for effective, minimally invasive control of active extravasation due to blunt renal trauma, even in kidneys with congenital malformations such as the horseshoe kidney.
Successful Endovascular Management of a Transected Horseshoe Kidney
Ben E. Paxton, MD ∙ Charles Y. Kim, MD ∙ Michael J. Miller, MD ∙ Rajan T. Gupta, MD
Contact: Rajan T. Gupta, MD. E-mail
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Citation: Paxton BE, Kim CY, Miller MJ, Gupta RT. Successful endovascular management of a transected horseshoe kidney. J Surg Radiol. 2011 Jan 1;2(1).
Received: August 31, 2010; Accepted: September 30, 2010; Published: September 30, 2010 Copyright: © 2010 Surgisphere Corporation. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
Contents |
Case Report
A 35-year-old male with no significant past medical history presented to Duke University Medical Center status post motor vehicle collision. The patient was an unrestrained moped driver when he collided with a stationary car. Physical examination at the time of patient presentation to the emergency department was remarkable for diffuse abdominal pain, without rebound or guarding. The patient's vital signs at the time of the primary trauma survey were as follow: blood pressure 98/52, heart rate 78 beats per minute, 18 respirations per minute, and oxygen saturation 98% on room air. He was hemodynamically stable at this time. Laboratory work-up revealed a hematocrit of 0.33. His urine was noted to be grossly bloody upon Foley catheter insertion.The patient had unrelated contrast-enhanced CT imaging prior to the accident which demonstrated the presence of a horseshoe kidney (Figure 1). In the emergency department, the patient underwent urgent contrast-enhanced CT of the abdomen and pelvis, which demonstrated a complete transection at the isthmus of the horseshoe kidney with an associated large hematoma measuring 8.9 x 8.7 cm that displaced the right side of the kidney anteriorly (Figure 2). In terms of arterial supply, the right aspect of the horseshoe kidney was supplied by a single right renal artery arising from the abdominal aorta in a normal expected location. The left aspect of the horseshoe kidney was supplied by a main left renal artery and an accessory left renal artery, which supplied the lower moiety and originated from the left common iliac artery (Figure 3). Two distinct sites of active extravasation were identified emanating from the right moiety at its fracture site on CT (Figures 4 and 5). No definite active extravasation was visualized in association with the left aspect of the kidney. Delayed images taken approximately 10 minutes after injection of IV contrast demonstrated the bilateral collecting systems to be grossly intact without definite extravasation of excreted contrast.
Figure 1. Single axial contrast-enhanced CT image at the level of L3 demonstrates patient's known horseshoe kidney on prior unrelated CT imaging.
Figure 2. Complete transection of horseshoe kidney at the isthmus with a large hematoma displacing transected horseshoe kidney anteriorly (arrows).
Figure 3. Accessory left renal artery arising from the left common iliac artery (arrow).
Figure 4. One of two primary sites of active extravasation emanating from the right moiety at its fracture site (arrowhead). Extravascular contrast is also visualized dependently within the retroperitoneal hematoma (arrow).
Figure 5. Another site of active extravasation (arrowhead) located inferiorly to the extravasation in Figure 4, also emanating from the right moiety at its fracture site. Extravascular contrast is again visualized dependently within the retroperitoneal hematoma (arrow).
The patient was subsequently transferred to Vascular and Interventional Radiology for further management based on the findings of active arterial extravasation. Abdominal arteriogram was performed which again demonstrated a transected horseshoe kidney with active extravasation from branches of the right renal artery (Figure 6). The renal parenchyma enhanced fairly symmetrically on both sides. The arterial supply to the horseshoe kidney was again confirmed, with a right and left renal arteries arising from their normal expected locations from the aorta and an accessory left renal artery from the left common iliac artery (Figure 7). Selective left renal arteriography demonstrated no evidence of active extravasation. At this point in the procedure, the patient developed hemodynamic instability, requiring aggressive volume resuscitation.
Figure 6. Delayed phase abdominal arteriogram in the nephrographic phase again depicts complete transection of the horseshoe kidney with separation of the left and right moieties, with relatively well-preserved parenchymal perfusion. A tiny site of active extravasation can be visualized from a branch of the right renal artery (arrow).
Figure 7. Abdominal arteriogram in the arterial phase demonstrates the arterial supply to the transected horseshoe kidney, with a single right renal artery (black arrow), dominant left renal artery (white arrow), and accessory left renal artery from the left common iliac artery (white arrowhead).
Subsequently, a Mikaelsson catheter was then used to select the right renal artery and arteriography was performed (Figure 8). A microcatheter and 90 degree angled 0.018 inch hydrophilic guidewire were advanced into the branch artery supplying the right lower moiety of the fractured horseshoe kidney, and a superselective right renal arteriogram was performed. This demonstrated two foci of active extravasation originating from two branches of the right renal artery (Figures 9 and 10). These two arterial branches were each successfully embolized with detachable microcoils until stasis of flow was achieved (Figure 11). Final renal arteriogram demonstrated no evidence of continued extravasation. Furthermore, the patient’s hemodynamic parameters stabilized at this point in time. Post procedure, the patient did well with stabilization of serial hematocrit levels.
Figure 8. Selective right renal arteriogram was performed, again demonstrating active extravasation from a branch of the right renal artery (arrow).
Figure 9. Superselective right renal arteriogram demonstrates prominent active extravasation from a branch of the right renal artery (arrows).
Figure 10. The injured branch artery illustrated in Figure 9 was embolized with coils; superselective injection distal to this branch demonstrates active extravasation of another small branch.
A follow-up IV contrast-enhanced CT scan of the abdomen and pelvis 2 days later demonstrated extravasation of contrast into the retroperitoneum on delayed images consistent with injury to the renal collecting systems. No active arterial extravasation was identified. The patient underwent urological intervention with placement of bilateral ureteral stents. The patient's subsequent hospital course was unremarkable and he was discharged in good condition. A follow up angiogram performed 4 weeks after initial stent placement showed no active extravasation, arteriovenous fistula, or pseudoaneurysm.
Figure 11. The second small branch illustrated in Figure 10 was embolized with coils, and additional coils (arrows) were continued to be packed proximally to the origin of the preceding embolized branch. Follow up selective angiogram confirms successful embolization with stasis of flow.
Discussion
Congenital fusion anomalies of the kidneys can generally be placed into 2 main categories: (1) horseshoe kidney and its variants and (2) crossed fused ectopia. Horseshoe kidney is the most common fusion anomaly with an overall prevalence of 0.2%, and is more common in males.1,2 It is caused by congenital fusion of the lower kidney poles with an isthmus that is either fibrous or parenchymal.3 Vascularization of the isthmus and adjacent parenchyma is markedly variable, and may arise from the aorta, the iliac arteries (common, internal, or external), the inferior mesenteric artery, or the sacral arteries.4,5 Bilateral single arteries occur in one-third of cases.4 However, various combinations of single and multiple renal hilar and isthmus vessels are seen in two-thirds of cases.3 The isthmus of the horseshoe kidney is supplied by a single vessel from the aorta in 65% of cases.6 The current case highlights this variable arterial supply with multiple bilateral renal arteries seen at angiography, with a single dominant superior renal artery bilaterally. Furthermore, the inferior left moiety had arterial supply from the left common iliac artery (Figures 3 and 7).
The horseshoe kidney is more prone to blunt abdominal trauma because of its low position and the presence of the isthmus across the midline.3 The fused kidney is not well protected by the ribs due to its low position in the abdomen, and it is prone to compression or fracture against the lumbar vertebral bodies in response to blunt abdominal force due to its location anterior to these structures.
The sequelae of blunt renal trauma range from simple contusion to complete shattering of the kidney or avulsion of the vascular pedicle, with the vast majority of renal injuries requiring only conservative treatment.7 The advent of minimally invasive therapies for the treatment of renal injury has led to a decrease in frequency of surgical intervention for the management of renal injury.8-10 Vascular injury from penetrating or blunt trauma in the hemodynamically stable or unstable patient, including rupture of renal parenchyma, shattered kidneys, and pedicle avulsions, can frequently be effectively treated with superselective catheter embolization.11 In situations where catheter-based therapy is unsuccessful or not clinically indicated, the range of surgical options can vary and often depend on the type and severity of the injury with considerations of additional factors such as collecting system involvement.
In the current case, we present a rare complete transection of a horseshoe kidney at the isthmus due to blunt abdominal trauma with two sites of active extravasation on initial CT imaging. This extravasation was successfully treated by embolization with coils. Few similar cases of transected horseshoe kidneys have been reported in the literature with endovascular treatment by embolization,12 endovascular treatment by stenting,13 and surgical management.14
In conclusion, superselective embolization may be used for effective, minimally invasive control of active extravasation due to blunt renal trauma, even in kidneys with congenital malformations such as the horseshoe kidney.
Disclosures
The authors have no disclosures or conflicts of interest related to this manuscript.
References
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- Esquena Fernández S, Trilla Herrera E, Abascal Junquera JM, Pérez M, Morote Robles J. Arterial embolization in the treatment of renal trauma of a horseshoe kidney. Arch Esp Urol. 2005 Dec;58(10):1075-7. [Article in Spanish]
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- Pascual Samaniego M, Bravo Fernandez I, Ruiz Serrano M, et al. Traumatic rupture of a horseshoe kidney. Actas Urol Esp 2006;30: 424-8.
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