Traumatic renal injury - AAST grade IV injury

Case contributed by Rania Adel Anan


Motor vehicle collision

Patient Data

Age: 15 years
Gender: Female

Loss of normal anatomical integrity of the lower pole of the right kidney with a hypoattenuating area (representing parenchymal laceration) and a perinephric hematoma showing high-density fluid inside measuring about 7 x 6 x 10 cm. Intact renal artery and vein. 

On the delayed phase images, there is an extravasation of contrast seen connected to the lower major calyx (which was increased in the images taken 30 minutes later) in keeping with a collecting system injury and urine leak. 

Mild amount of free fluid seen in the pelvis.

Full catheterized intact urinary bladder.

Incidentally discovered:

  • retroaortic left renal vein (anatomical variant)
  • replaced right hepatic artery arising from the SMA (anatomical variant)

Case Discussion

There is an injury to the right kidney with a perinephric hematoma.

The patient was recalled for a delayed study, 30 minutes after the initial images had been reviewed and the amount of extravasated contrast from the urinary system was increased. 

Urinary extravasation classifies this as a grade IV injury on the American Association for the Surgery of Trauma (AAST) renal injury scale. 

This case also illustrates the importance of appropriate protocolling of trauma CT - when a renal injury is clinically suspected especially in the presence of hematuria, this should lead to either an automatic acquisition of an excretory phase study or at least a 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 inuries and pneumothoraces.

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