Ureteropelvic junction injuries secondary to blunt abdominal trauma

PURPOSE: To describe the clinical and imaging findings of ureteropelvic junction (UPJ) injuries caused by blunt trauma. MATERIALS AND METHODS: In two children (aged 10 and 16 years) and eight adults (aged 23-82 years) with UPJ injuries, findings at computed tomography (CT) (n = 10), excretory urography (n = 6), and retrograde pyelography (n = 8) were retrospectively reviewed to identify the location and extent of contrast material extravasation. Clinical and follow-up data were correlated with radiologic findings. RESULTS: CT and urography played complementary roles in diagnosis. UPJ avulsion, defined as complete transection of the ureter with no filling of the ipsilateral ureter below the level of the UPJ, was diagnosed in four patients. UPJ laceration, defined as contrast material extravasation from the UPJ with contrast material in the ipsilateral ureter distal to the point of injury, was diagnosed in six patients. Medial perirenal contrast extravasation was seen in all 10 patients but failed to help differentiate UPJ avulsion from laceration. A distinctive pattern of contrast material extravasation at CT termed ''circumrenal urinoma'' was present in five patients and was found to be specific for UPJ injury. CONCLUSION: Medial perinephric contrast material extravasation was highly suggestive of UPJ injury. Demonstration of ureteral filling differentiated UPJ laceration from avulsion.