The AAST liver injury scale

Grade I

     Minor lacerations or contusions. These injuries involve superficial tears or bruising of the liver tissue with minimal bleeding and no significant disruption to liver function.

• Subcapsular Hematoma: <10% surface area
• Laceration: capsular tear, <1 cm parenchymal depth

Grade II

     Moderate lacerations with bleeding. These injuries are more severe than Grade I and may require close monitoring but often can be managed without surgery.

• Subcapsular Hematoma: 10-50% surface area
• Intraparenchymal Hematoma: <10 cm diameter
• Laceration: capsular tear, 1-3 cm parenchymal depth, <10 cm length

Grade III

     Deep lacerations that extend into the liver parenchyma. This grade may involve significant bleeding and requires careful assessment to decide between surgical and non-surgical management.

• Subcapsular Hematoma: >50% surface area; ruptured subcapsular or parenchymal hematoma
• Intraparenchymal Hematoma: >10 cm
• Laceration: capsular tear >3 cm parenchymal depth
• Any injury in the presence of a liver vascular injury or active bleeding contained within liver parenchyma

Grade IV

     Lacerations involving major blood vessels within the liver. These injuries often lead to severe bleeding and usually require surgical intervention to control hemorrhage.

• Laceration: parenchymal disruption involving 25-75% of a hepatic lobe or involves 1-3 Couinaud segments
• Active bleeding extending beyond the liver parenchyma into the peritoneum

Grade V

      Extensive liver damage involving more than 75% of a hepatic lobe or causing major disruption of the hepatic veins or vena cava. These injuries are critical and often life-threatening.

• Laceration: parenchymal disruption involving >75% of hepatic lobe
• Vascular: juxtahepatic venous injuries (retrohepatic vena cava / central major hepatic veins)

Grade VI

• Vascular: hepatic avulsion

The AAST kidney injury scale

Grade I

• subcapsular hematoma and/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 ureteropelvic 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

The AAST spleen injury scale

Grade I

• subcapsular hematoma <10% of surface area
• parenchymal laceration <1 cm depth
• capsular tear

Grade II

• subcapsular hematoma 10-50% of surface area
• intraparenchymal hematoma <5 cm
• parenchymal laceration 1-3 cm in depth

Grade III

• subcapsular hematoma >50% of surface area
• intraparenchymal hematoma ≥5 cm
• parenchymal laceration >3 cm in depth
• ruptured subcapsular or intraparenchymal hematoma

Grade IV

• any injury in the presence of a splenic vascular injury* or active bleeding confined within splenic capsule
• parenchymal laceration involving segmental or hilar vessels producing >25% devascularisation

Grade V

• shattered spleen
• any injury in the presence of splenic vascular injury* with active bleeding extending beyond the spleen into the peritoneum