AAST kidney injury scale

Dr Jeremy Jones and A.Prof Frank Gaillard et al.

The American Association for the Surgery of Trauma (AAST) renal injury scale 3-4 is the most widely used grading system for renal trauma at the time of writing (late 2016). Severity is assessed according to the depth of renal parenchymal damage and involvement of the urinary collecting system and renal vessels.

Classification

  • 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 confined to retroperitoneum
  • 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 bilateral injuries up to grade III.

If a renal injury is detected on a routine trauma portal venous phase CT of the abdomen without evidence of urine extravasation, then a delayed phase at 5-15 minutes should be considered to assess for urine extravasation, especially if there are clinical signs of collecting system injury (e.g. haematuria or blood at the meatus). 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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Article information

rID: 1972
Systems: Urogenital, Trauma
Synonyms or Alternate Spellings:
  • AAST grading of renal trauma
  • Renal trauma assessment
  • Renal trauma grade
  • Renal injury grading

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Cases and figures

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    Figure 1
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    Case 1: grade I
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    Figure 2
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    Case 2: grade II
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    Figure 3
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    Case 3: grade IV
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    Figure 4
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    Case 4: grade IV
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    Figure 5
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    Case 5: grade IV
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    Case 11: grade IV
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    Case 6: grade V : left kidney
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    Case 7: grade V : shattered kidney (+ splenic laceration)
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    Case 8: grade V + concurrent splenic injury
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    Case 9: grade V
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    Case 10: grade V
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