Table 3.
Organ injury scale (OIS) of the American Association for Surgery of Trauma (AAST): 2018 revision
| Spleen | Liver | |||
|---|---|---|---|---|
| Grade | Type | Injury description | Type | Injury description |
| I | Haematoma | Subcapsular, < 10% surface area | Haematoma | Subcapsular, < 10% surface area |
| Laceration | Capsular tear, < 1% parenchymal depth | Laceration | Capsular tear, < 1% parenchymal depth | |
| II | Haematoma | Subcapsular, 10–50% surface area | Haematoma | Subcapsular, 10–50% surface area |
| Intra-parenchymal, < 5 cm in diameter | Intra-parenchymal, < 10 cm in diameter | |||
| Laceration | 1–3 cm parenchymal depth | Laceration | Capsular tear, 1–3 cm parenchymal depth, < 10 cm length | |
| III | Haematoma | Subcapsular, > 50% surface area | Haematoma | Subcapsular, > 50% surface area of ruptured subcapsular or parenchymal haematoma |
| Ruptured subcapsular or parenchymal haematoma ≥5 cm | intraparenchymal > 10 cm | |||
| Laceration | > 3 cm parenchymal depth or involving trabecular vessels | Laceration | Capsular tear, > 3 cm parenchymal depth | |
| Vascular | Vascular injury with active bleeding contained within liver parenchyma | |||
| IV | Laceration | Parenchymal laceration involving segmental or hilar vessels producing > 25% devascularisation | Laceration | Parenchymal disruption involving 25–75% hepatic lobe or involves 1–3 Couinaud segments |
| Vascular | Any injury in the presence of a splenic vascular injury or active bleeding confined within splenic capsule | Vascular | Vascular injury with active bleeding breaching the liver parenchyma into the peritoneum | |
| V | Laceration | Shattered spleen | Laceration | Parenchymal disruption involving > 75% of hepatic lobe |
| Vascular | Any injury in the presence of splenic vascular injury with active bleeding extending beyond the spleen into the peritoneum | Vascular | Juxtavenous hepatic injuries; i.e. retrohepatic vena cava/central major hepatic veins | |
| Additional points: | ||||
| Advance one grade for multiple injuries up to grade III | ||||
| Vascular injury (i.e. pseudoaneurysm or AV fistula), appears as a focal collection of vascular contrast which decreases in attenuation on delayed images | ||||
| Active bleeding, focal or diffuse collection of vascular contrast which increases in size or attenuation on a delayed phase | ||||