AAST kidney injury scale 2018


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

— Shattered kidney
— Avulsion of renal hilum or laceration of the main renal artery or vein: devascularisation of a kidney due to hilar injury
— Devascularised kidney with active bleeding



Note: Advance one grade for bilateral renal 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.

Link to original article: Trauma Acute Care Surg; 85(6):1119- 1122