Table 1.

Organ Injury Scale (OIS) of the American Association for Surgery of Trauma (AAST): 2018 revision.

AAST	AIS		Liver	Spleen	Kidney
I	2	Hematoma	Subcapsular, <10% surface area	Subcapsular, <10% surface area	Subcapsular hematoma and/or parenchymal contusion without laceration
		Laceration	Capsular tear, <1% parenchymal depth	Capsular tear, <1% parenchymal depth
II	2	Hematoma	Subcapsular, 10–50% surface area, intra-parenchymal, <10 cm in diameter	Subcapsular, 10–50% surface area Intra-parenchymal, <5 cm in diameter	Perirenal hematoma confined to Gerota fascia
		Laceration	Capsular tear, 1–3 cm parenchymal depth, <10 cm length	1–3 cm parenchymal depth	Renal parenchymal laceration ≤1 cm depth without urinary extravasation
III	3	Hematoma	Subcapsular, >50% surface area of ruptured subcapsular or parenchymal hematoma; intraparenchymal >10 cm	Subcapsular, >50% surface area Ruptured subcapsular or parenchymal hematoma ≥5 cm
		Laceration	Capsular tear, >3 cm parenchymal depth	>3 cm parenchymal depth or involving trabecular vessels	Renal parenchymal laceration >1 cm depth without collecting system rupture or urinary extravasation
		Vascular	Vascular injury with active bleeding contained within liver parenchyma		Any injury in the presence of a kidney vascular injury or active bleeding contained within Gerota fascia
IV	4	Laceration	Parenchymal disruption involving 25–75% of hepatic lobe or 1–3 segments	Parenchymal laceration involving segmental or hilar vessels producing >25% devascularization	Parenchymal laceration extending into urinary collecting system with urinary extravasation Renal pelvis laceration and/or complete ureteropelvic disruption
		Vascular	Vascular injury with active bleeding breaching the liver parenchyma into the peritoneum	Any injury in the presence of a splenic vascular injury or active bleeding confined within splenic capsule	Segmental renal vein or artery injury Active bleeding beyond Gerota fascia into the retroperitoneum or peritoneum Segmental or complete kidney infarction(s) due to vessel thrombosis without active bleeding
V	5	Laceration	Parenchymal disruption involving >75% of hepatic lobe	Shattered spleen	Shattered kidney with loss of identifiable parenchymal renal anatomy
		Vascular	Juxtavenous hepatic injuries; i.e., retrohepatic vena cava/central major hepatic veins	Any injury in the presence of splenic vascular injury with active bleeding extending beyond the spleen into the peritoneum	Main renal artery or vein laceration or avulsion of hilum Devascularized kidney with active bleeding

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 that decreases in attenuation on delayed images. Active bleeding: focal or diffuse collection of vascular contrast that increases in size or attenuation in a delayed phase. Details from [40,41].