Renal trauma grading

Renal trauma grading is often done using the American Association for the Surgery of Trauma (AAST) 3-4 according to depth of damage and involvement of the urinary collecting system and renal vessels.


  • grade I: contusion or non-enlarging subcapsular perirenal haematoma, and no laceration
  • grade II: superficial laceration <1 cm depth and does not involve the collecting system (no evidence of urine extravasation), non-expanding perirenal haematoma
  • grade III: laceration >1 cm without extension into the renal pelvis or collecting system (no evidence of urine extravasation)
  • grade IV
    • laceration extends to renal pelvis or urinary extravasation
    • vascular: injury to main renal artery or vein with contained haemorrhage
    • segmental infarctions without associated lacerations
    • expanding subcapsular haematomas compressing the kidney
  • grade V

NB: Advance one grade for multiple injuries up to grade III.

If a renal injury is seen on a routine portal phase CT of the abdomen, and there is no urine extravasation, a delayed series at 5-15 minutes should be considered to check for urine extravasation. This should not necessarily be performed if the patient is unstable or if there are other large, life-threatening injuries.

See also

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