Imaging of renal trauma: A comprehensive review

Computed tomography (CT) is the modality of choice in the evaluation of blu nt renal injury. Intravenous urography is used primarily for gross assessme nt of renal function in hemodynamically unstable patients. Selective renal arteriography or venography can provide detailed information regarding vasc ular injury. Retrograde pyelography is valuable in assessing ureteral and r enal pelvic integrity in suspected ureteropelvic junction injury. Ultrasono graphy is useful in detecting hemoperitoneum in patients with suspected int raperitoneal injury but has limited value in evaluating those with suspecte d extraperitoneal injury. Occasionally, radionuclide renal scintigraphy or magnetic resonance imaging may prove helpful. Renal injuries can be classif ied into four large categories based on imaging findings. Category I renal injuries include minor cortical contusion, subcapsular hematoma, minor lace ration with limited perinephric hematoma, and small cortical infarct. Categ ory II lesions include major renal lacerations extending to the medulla wit h or without involvement of the collecting system and segmental renal infar ct. Category III lesions are catastrophic renal injuries and include multip le renal lacerations and vascular injury involving the renal pedicle. Categ ory IV injuries are ureteropelvic junction injuries. CT is particularly use ful in evaluating traumatic injuries to kidneys with preexisting abnormalit ies and can help assess the extent of penetrating injuries in selected pati ents with limited posterior stab wounds. Integration of the imaging finding s in renal injury with clinical information is critical in developing a tre atment plan.