The Organ Injury Scale (OIS) for hepatic trauma, Grade IV liver injury is defined as:
- A Parenchymal disruption involving 25–75% of a hepatic lobe or 1–3 Couinaud segments within a single lobe ✓
- B Parenchymal laceration <3 cm depth in the parenchyma
- C Hepatic avulsion or juxtahepatic venous injury (retrohepatic IVC/major hepatic veins)
- D Subcapsular haematoma occupying <10% surface area
Correct answer: A. Parenchymal disruption involving 25–75% of a hepatic lobe or 1–3 Couinaud segments within a single lobe
Explanation
The AAST OIS for hepatic injuries grades from I to VI: Grade I — subcapsular haematoma <10% surface, laceration <1 cm; Grade II — subcapsular haematoma 10–50%, laceration 1–3 cm; Grade III — subcapsular haematoma >50% or expanding, laceration >3 cm depth; Grade IV — parenchymal disruption involving 25–75% of a lobe or 1–3 Couinaud segments; Grade V — disruption >75% of a lobe or more than 3 Couinaud segments, or juxtahepatic venous injury; Grade VI — hepatic avulsion. Grade IV injuries often require operative intervention.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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