In stable patients, computed tomography (CT) with intravenous contrast is the imaging study of choice for demonstrating renal parenchymal injury, perirenal/ret-roperitoneal hematomas, urine extravasation, injuries to the renal hilum, and associated intraabdominal organ injuries. It is essential to obtain both an arteriographic phase to assess for major vessel injury and a delayed pyelographic phase to assess for contrast extravasation.

Parenchymal contusions are noted as areas of reduced enhancement, whereas lacerations appear as linear, blood-containing areas that interrupt the parenchyma. Hematomas are visible as hyperattenuating collections that, if large and confined to the subcapsular space, can compress the adjacent renal parenchyma.

Ultrasonography is sometimes used as an initial screen but offers limited value. For example, although ultrasound can demonstrate perirenal fluid collections, it cannot distinguish fresh blood from extravasated urine.