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Trauma to a Horseshoe Kidney: Case Report and Review of the Literature

ABSTRACT

A horseshoe kidney (HSK) is the most common congenital renal fusion anomaly. It occurs in approximately 1 in 400 persons, with a 2:1 male:female incidence. Traumatic synchronous, multiorgan injury in the setting of anomalous anatomy adds to the complexity of surgical exposure and creates a formidable hemostatic challenge. We present a 30-year-old male with multiorgan injury secondary to blunt abdominal trauma sustained during a motor vehicle accident. We describe the preoperative evaluation that led to the identification of the HSK and other associated intra-abdominal injuries and the subsequent surgical procedure. Surgical management of blunt abdominal trauma to an HSK is difficult due to multiple variations in vascular anatomy and the location of this renal anomaly. Such anatomical variations can make reconstruction and preservation of the damaged kidney very challenging.

Prakash R Paragi, Pauline H Go, Zachary Klaassen, Mark Ingram

Submitted March 16, 2011 - Accepted for Publication May 11, 2011

KEYWORDS: Horseshoe kidney; Renal; Trauma

CORRESPONDENCE: Prakash R Paragi, MS, MD, Director of Minimally Invasive Surgery, Saint Barnabas Medical Center, 94 Old Short Hills Road, Livingston, NJ 07039 USA ().

CITATION: Urotoday Int J. 2011 Aug;4(4):art47. doi:10.3834/uij.1944-5784.2011.08.03

ABBREVIATIONS AND ACRONYMS: CT, computed tomography; FAST, Focused Assessment with Sonography in Trauma; HSK, horseshoe kidney; MVA, motor vehicle accident.

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INTRODUCTION

Approximately 8% to 10% of abdominal traumas result in an injury to the kidney; 80% of the injuries are produced by blunt trauma [1]. Traumatic, synchronous multiorgan injury in the setting of anomalous anatomy adds to the complexity of surgical exposure and creates a formidable hemostatic challenge. Thus, early recognition of a congenital anomaly is essential in directing a surgical strategy that aims to achieve unconstrained operative exposure.

We present a case of multiorgan injury secondary to blunt abdominal trauma that was sustained during a motor vehicle accident (MVA). We describe the preoperative evaluation that led to the identification of a horseshoe kidney (HSK) and other associated intra-abdominal injuries.

CASE REPORT

A 30-year-old male was brought to a level I trauma center following a high-speed MVA. At the time of presentation, he was hemodynamically stable. He complained of diffuse abdominal pain and pain over the posterior neck and lower thoracic spine. A diagonal, seatbelt-induced abrasion was noted across his chest and abdomen. His abdomen was minimally distended. There were sluggish bowel sounds and marked tenderness over the left flank and left upper quadrant. Urethral catheterization revealed hematuria.

Presurgical evaluation. Focused Assessment with Sonography in Trauma (FAST) was significant for perisplenic fluid, a heterogeneous left kidney, and scant pelvic fluid. A chest x-ray demonstrated fractures of the left 10th and 11th ribs without evidence of hemothorax or pneumothorax. A contrast-enhanced computed tomography (CT) scan of the abdomen and pelvis demonstrated a ruptured spleen and grade III laceration of the left wing of an HSK (Figure 1; Figure 2). The patient became acutely hypotensive immediately following the CT scan and was taken to the operating room for emergency surgical exploration.

Surgical procedures. Approximately 200 mL of intraperitoneal blood was identified and evacuated. The lacerated spleen was bleeding profusely, requiring hilar splenectomy. A large, expanding retroperitoneal hematoma extended from the lesser sac to the pelvic brim and up to both paracolic gutters. Hemostasis was initially achieved by clamping the supraceliac aorta and infrarenal aorta. Medial rotation of the left-sided peritoneal viscera revealed a lacerated, profusely bleeding left wing of the HSK, at which time the supraceliac clamp was repositioned superior to the renal arteries. The left renal pedicle was isolated and controlled en masse with a noncrushing vascular clamp, while the suprarenal aortic clamp was removed. The isthmus was transected and removed with the entire left wing of the HSK, leaving a portion of the isthmus and the right wing of the HSK. Following ligation of the left renal pedicle, the infrarenal and left renal cross clamps were removed with no deterioration of vital signs. The total aortic cross-clamp time was 36 minutes.

Postoperatively, the patient developed a left subdiaphragmatic abscess (Figure 3). The abscess completely resolved following treatment with antibiotics and CT-guided drainage.

DISCUSSION

HSK is the most common congenital renal fusion anomaly; it occurs in approximately 1 in 400 persons, with a 2:1 male:female incidence [2]. First described by da Carpi in 1522, these renal abnormalities occur when the nephrogenic blastema fuse during the 4th and 8th weeks of embryogenesis; the action results in fusion of the renal parenchyma on each side of the vertebral column at the inferior poles in 90% of cases [3]. The fused renal mass is joined by an isthmus of parenchymal or fibrous tissue at the level of the 3rd or 4th lumbar vertebrae (L3/L4), forming a horseshoe around the inferior mesenteric artery [3,4]. Consequently, proper ascent and medial rotation of the kidneys fails to occur, and the isthmus becomes positioned anterior to the vertebral column [4]. The blood supply is variable, with bilateral single renal hilar arteries identified in 30% of cases and various combinations of single and multiple renal hilar and isthmus vessels seen in the remaining 70% [5].

It is opined that the characteristic fixed position of HSKs over the vertebral column, as well as the lack of protection normally afforded by the lower ribs, renders these anomalous kidneys much more susceptible to injury during blunt abdominal trauma [4]. This is particularly evident in the case of MVAs, during which the HSK is compressed over the lumbar vertebrae by the seatbelt. The accident commonly results in the seatbelt syndrome, which includes hollow viscus perforation, lumbar spine injury, and injury to other solid organs such as the liver and/or spleen [4].

Agrawal et al [6] recently reported a case of blunt abdominal trauma to a patient with a known HSK. The patient was initially managed conservatively, but became hemodynamically unstable within 7 hours of hospitalization. During exploratory laparotomy, it was noted that the isthmus of the HSK was completely avulsed. Eventual extirpation of the left wing of the HSK was needed in order to achieve hemostasis. Due to the highly vascular nature and anomalous vascular anatomy of the isthmus, any suspected injury to this portion of the HSK should be monitored closely during conservative management with a low threshold for surgical intervention [6].

Recent reports have suggested an endovascular approach to treating patients with HSK trauma [7,8]. Esquena Fernandez et al [7] successfully embolized the left renal artery in a 19-year-old patient with HSK trauma and persistent extravasation from the left wing of the HSK. Trottier et al [8] reported a case of HSK trauma in a 21-year-old patient with an avulsed accessory right polar artery originating from the right common iliac artery. The injury was subsequently treated with a 10-mm diameter, 6-cm length, self-expandable covered stent. Although initially treated with an endovascular approach, the patient subsequently developed a 3L retroperitoneal hematoma secondary to subclinical backbleeding from the lacerated polar artery stump that required exploratory laparotomy.

Trauma to abnormal kidneys should be treated on an individual basis, with the patient's clinical course ultimately dictating the management approach [9]. Because one-third to one-half of patients with HSK are asymptomatic, this anomaly is often discovered incidentally; rarely, it is discovered in the emergency department following blunt abdominal trauma [2]. Therefore, guidelines for the initial management of patients with HSK are similar to those used to evaluate the general population when they present with blunt abdominal trauma. Ultrasonagraphy is a well-established imaging modality in the initial assessment of these patients, followed by CT imaging of hemodynamically stable patients for whom ultrasonagraphy is equivocal [2]. Special surgical considerations must be taken once an HSK has been identified. The HSK must be treated as a solitary kidney, with meticulous attention being paid to the blood supply [10]. Detailed preoperative urologic evaluation, including a complete multiple-exposure intravenous pyelogram (IVP) and renal arteriography, is recommended where possible to identify an anomalous blood supply or drainage system [4,9]. Contusions and parenchymal lacerations can safely be managed with a trial of conservative therapy, while emergency surgical intervention is indicated in the case of a ruptured or shattered kidney or injury to the pedicle [11].

CONCLUSIONS

Initial evaluation of any patient presenting to the emergency department following blunt abdominal trauma should include abdominal ultrasonagraphy or FAST, followed by a CT scan if the patient is hemodynamic stabile. When an HSK is identified, a thorough preoperative urologic evaluation is recommended, if possible. The evaluation is used to determine variability in blood supply and drainage systems and to formulate an appropriate surgical strategy. Emergent surgical intervention is only indicated when hemodynamic stability cannot be attained or there is extensive parenchymal or vascular pedicle injury. Surgical management of blunt abdominal trauma to an HSK is difficult due to multiple variations in vascular anatomy and the location of this renal anomaly. Such anatomical variations can make reconstruction and preservation of the damaged kidney very challenging.

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