AAST kidney injury scale

Dr Craig Hacking and A.Prof Frank Gaillard et al.

The 2018 update of the American Association for the Surgery of Trauma (AAST) renal injury scale is the most widely used grading system for renal trauma at the time of writing (late 2018) 8. Severity is assessed according to the depth of renal parenchymal damage and involvement of the urinary collecting system and renal vessels.

Classification

  • grade I: 
    • subcapsular hematoma or contusion, without laceration
  • grade II:
    • superficial laceration ≤1 cm depth not involving the collecting system (no evidence of urine extravasation)
    • perirenal hematoma confined within the perirenal fascia
  • grade III:
    • laceration >1 cm not involving the collecting system (no evidence of urine extravasation)
    • vascular injury or active bleeding confined within the perirenal fascia
  • grade IV
    • laceration involving the collecting system with urinary extravasation
    • laceration of the renal pelvis and/or complete uretopelvic disruption
    • vascular: injury to segmental renal artery or vein
    • segmental infarctions without associated active bleeding (i.e. due to vessel thrombosis)
    • active bleeding extending beyond the perirenal fascia (i.e. into the retroperitoneum or peritoneum)
  • 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. hematuria or blood at the meatus) 5. 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
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

  • 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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