How are liver injuries graded and managed?

Liver Injury Grading and Management

Liver injuries are graded using the American Association for the Surgery of Trauma (AAST) scale and the World Society of Emergency Surgery (WSES) classification, with management determined primarily by hemodynamic status rather than anatomical grade alone. 1

Grading Systems

AAST Liver Injury Scale

• Grade I:

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

• Grade II:

  • Hematoma: Subcapsular, 10-50% surface area; intraparenchymal, <10 cm diameter
  • Laceration: 1-3 cm parenchymal depth, <10 cm in length 1

• Grade III:

  • Hematoma: Subcapsular, >50% surface area or expanding; ruptured subcapsular or parenchymal hematoma; intraparenchymal hematoma >10 cm
  • Laceration: >3 cm parenchymal depth 1

• Grade IV:

  • Laceration: Parenchymal disruption involving 25-75% of hepatic lobe
  • Vascular: Juxtavenous hepatic injuries (retrohepatic vena cava/central major hepatic veins) 1

• Grade V:

  • Vascular: Hepatic avulsion 1

Note: Advance one grade for multiple injuries up to grade III 1

WSES Classification System

This classification incorporates both AAST anatomical grading and hemodynamic status:

• Minor (WSES grade I): AAST grade I-II, hemodynamically stable 1
• Moderate (WSES grade II): AAST grade III, hemodynamically stable 1
• Severe (WSES grade III): AAST grade IV-V, hemodynamically stable 1
• Severe (WSES grade IV): ANY AAST grade with hemodynamic instability 1

Management Approach

Hemodynamically Stable Patients (WSES grades I-III)

• Non-operative management (NOM) is the standard of care for hemodynamically stable patients regardless of injury grade 1

• Initial assessment:

  • CT scan with intravenous contrast to define anatomic injury and identify associated injuries 1
  • Serial clinical examination, laboratory tests, and hemodynamic monitoring 1

• Grade-specific management:

  • Minor injuries (WSES grade I):

    • Observation with serial hemoglobin measurements 2
    • Discharge when clinically stable with follow-up imaging 1

  • Moderate injuries (WSES grade II):

    • Admission for close monitoring 1
    • Consider angiography with embolization for arterial blush on CT 1
    • Serial clinical and laboratory evaluation 1

  • Severe injuries (WSES grade III):

    • ICU admission for intensive monitoring 1
    • Angiography with embolization for arterial blush or evidence of active bleeding 1
    • Correction of coagulopathy if present 2

Hemodynamically Unstable Patients (WSES grade IV)

• Operative management is mandatory regardless of AAST grade 1

• Operative techniques based on injury severity:

  • Temporary perihepatic packing and damage control surgery for uncontrolled bleeding 3, 4
  • Pringle maneuver (hepatic vascular occlusion) for controlling bleeding 4
  • Direct suturing of lacerations or omental packing for moderate injuries 4
  • Selective hepatic artery ligation for arterial bleeding 4
  • Formal hepatic resection for severe parenchymal disruption (rarely needed) 4

Complications and Follow-up

• Complications occur in approximately 11% of high-grade injuries managed non-operatively: 5

  • Delayed bleeding (managed by angioembolization or surgery) 5
  • Biliary complications (bile leaks, bilomas) 5
  • Hepatic abscess formation 5
  • Hepatic necrosis (particularly after angioembolization) 3, 5

• Follow-up:

  • Serial imaging (ultrasound or CT) to monitor hematoma resolution 2
  • Laboratory monitoring of liver function 2
  • Long-term follow-up to assess for delayed complications 2

Common Pitfalls and Caveats

• Hemodynamic status trumps anatomical grade in management decisions - even low-grade injuries with hemodynamic instability require operative management 1

• Non-operative management should only be attempted in centers with:

  • Capability for intensive monitoring 1
  • Immediate access to angiography 1
  • Immediately available operating room 1
  • Immediate access to blood products 1

• Delayed rupture can occur days after initial presentation, necessitating continued vigilance even when patients appear stable 2

• Grade IV-V injuries have significantly higher mortality rates (up to 63% with ISS >20) compared to lower grades 6

• Penetrating injuries, particularly gunshot wounds, have higher mortality rates (23%) compared to stab wounds (4%) 6