How is a splenic injury graded and managed in a hemodynamically stable patient, considering the American Association for the Surgery of Trauma (AAST) grading system?

Splenic Injury Grading and Management in Hemodynamically Stable Patients

AAST Grading System

The American Association for the Surgery of Trauma (AAST) Organ Injury Scale classifies splenic injuries from Grade I through V based on anatomic severity, which directly guides intervention decisions. 1

Grade Definitions:

• Grade I: Subcapsular hematoma covering <10% of surface area or capsular tear <1 cm deep into parenchyma 1

• Grade II: Subcapsular hematoma covering 10-50% of surface area, intraparenchymal hematoma <5 cm diameter, or laceration 1-3 cm deep not involving trabecular vessels 1

• Grade III: Subcapsular hematoma >50% of surface area or expanding/ruptured, intraparenchymal hematoma >5 cm, or laceration >3 cm deep involving trabecular vessels 1

• Grade IV: Laceration of segmental or hilar vessels causing major devascularization (>25% of spleen) 1

• Grade V: Completely shattered spleen or hilar vascular injury causing complete devascularization 1

WSES Classification System

The World Society of Emergency Surgery integrates both anatomic grade and hemodynamic status to create a more clinically relevant classification. 1

• WSES Class I (Minor): Hemodynamically stable with AAST Grade I-II 1
• WSES Class II (Moderate): Hemodynamically stable with AAST Grade III 1
• WSES Class III (Severe): Hemodynamically stable with AAST Grade IV-V 1
• WSES Class IV (Critical): Hemodynamically unstable with any AAST grade 1

Management Algorithm for Hemodynamically Stable Patients

Grade I-II Injuries (WSES Class I):

Observation with serial monitoring is sufficient for low-grade injuries without contrast blush. 2

• Admit for observation with serial abdominal examinations and hematocrit checks every 6 hours for 24-72 hours 2
• Non-operative management success rate exceeds 95% 2
• Do NOT perform routine angiography/angioembolization unless contrast blush is present on CT 3
• If contrast blush is present (even in Grade I-II), proceed to angiography/angioembolization as failure rates without intervention reach 67-82% 3, 2

Grade III Injuries (WSES Class II):

Grade III injuries without contrast blush should be managed non-operatively with close observation, NOT routine prophylactic angioembolization. 3

• Non-operative management with intensive monitoring is appropriate for patients without vascular abnormalities 2
• Prophylactic angioembolization for Grade III injuries without blush increases morbidity (47% vs 10%) without significantly reducing failure rates 3
• NOM failure occurs in only 3% of Grade III lesions without blush when angioembolization is not performed 3
• However, if contrast blush, pseudoaneurysm, or arteriovenous fistula is present, proceed immediately to angiography/angioembolization 3, 2

Grade IV-V Injuries (WSES Class III):

All hemodynamically stable patients with Grade IV-V injuries should undergo angiography/angioembolization regardless of contrast blush presence. 3

• Failure rates for Grade IV injuries without angioembolization reach 43.7% vs 17.3% with intervention 3
• Failure rates for Grade V injuries without angioembolization reach 83.1% vs 25.0% with intervention 3
• Centers with angioembolization rates >10% demonstrate significantly higher spleen salvage rates and reduced mortality 3
• More than 80% of Grade IV-V injuries can be successfully managed non-operatively when angioembolization is utilized 3

Critical CT Findings Requiring Intervention

Any contrast blush, pseudoaneurysm, or arteriovenous fistula mandates angiography/angioembolization regardless of AAST grade. 3, 2

• Contrast blush predicts need for intervention with 83% accuracy 3
• Intraperitoneal blush carries higher risk of hemodynamic deterioration than intraparenchymal bleeding and is an independent risk factor for operative management 3
• Between 2.3-47% of CT-detected contrast blush may not be confirmed at angiography, but proceeding with angiography without embolization doubles the risk of rebleeding and NOM failure 3

Angioembolization Technique

Proximal embolization using coils is preferred over temporary agents. 3

• Proximal and distal embolization show equivalent rates of major infarctions, infections, and major rebleeding 3
• Distal embolization carries higher rates of minor complications (15.9-25.2% vs 2.8-11.6%) 3
• For multiple vascular abnormalities or severe lesions, use proximal or combined embolization after confirming permissive pancreatic vascular anatomy 3

Timing Considerations

Earlier angioembolization correlates with reduced splenectomy rates—timing matters. 3

• A multicenter study of 10,000 patients demonstrated that earlier angioembolization resulted in fewer splenectomies 3
• In centers where angioembolization is not rapidly available, consider operative management for patients with intraperitoneal blush due to high risk of rapid deterioration 3

Common Pitfalls

• Do not routinely embolize Grade III injuries without vascular abnormalities—this increases morbidity without improving outcomes 3, 2
• Do not rely solely on anatomic grade—hemodynamic status and CT findings (particularly contrast blush) are equally or more important 1
• Do not delay angioembolization in high-grade injuries—delay increases failure risk and splenectomy rates 3
• Do not assume absence of blush at angiography means no intervention needed if CT showed blush—consider proximal embolization as rebleeding risk doubles without it 3