Renal trauma: AAST grade IV injury

Case contributed by Dr Vikas Shah


Fall, hit flank on hard edge. Attends 12 hours after injury with hematuria and worsening pain.

Patient Data

Age: 55 years
Gender: Female

Signs of injury to the right kidney with a perinephric hematoma and high density fluid inferiorly in the right retroperitoneal space. Loss of normal anatomical integrity of the lower pole extending from cortical surface to medulla and collecting system. Intact renal artery and vein. High density material within the urinary bladder on the venous phase images. No other abnormalities.

The patient was returned to the emergency department without contemporaneous image review. They were then recalled for a delayed study at 60 minutes after the initial images had been reviewed.

CT acquired 60 minutes after contrast administration


On the delayed phase images, there is leak of contrast around the proximal right ureter in keeping with a collecting system injury and urine leak. There are filling defects in the collecting system and urinary bladder in keeping with blood clots.

Case Discussion

There is a perinephric hematoma and blood in the collecting system. The urinary extravasation classifies this is as a grade IV injury on the American Association for the Surgery of Trauma (AAST) renal injury scale. A conservative pathway was followed and subsequent ultrasound imaging (not shown here) showed a normal right kidney.

This case also illustrates the importance of appropriate protocolling of trauma CT - the presence of hematuria following a flank injury should lead to either the automatic acquisition of an excretory phase study or at the least contemporaneous review of the portal venous phase images to allow a prompt decision about further imaging to be made. Best practice also dictates imaging of the chest to look for rib and lung injuries and pneumothoraces.

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