# Splenic Trauma: Embolization vs. Splenectomy

## Introduction

The spleen is the most commonly injured solid organ in blunt abdominal trauma. **Non-operative management (NOM)** with or without splenic artery embolization (SAE) has become the standard of care for hemodynamically stable patients, achieving splenic salvage rates exceeding **90%**. Understanding the role of embolization in augmenting NOM and the indications for operative splenectomy is essential for interventional radiologists.

## AAST Spleen Injury Grading Scale

| AAST Grade | Injury Description | Management |
|-----------|-------------------|------------|
| I | Subcapsular hematoma <10%; laceration <1 cm depth | NOM (observation) |
| II | Subcapsular hematoma 10-50%; laceration 1-3 cm | NOM (observation) |
| III | Subcapsular hematoma >50% or expanding; laceration >3 cm | NOM + SAE (if stable) |
| IV | Segmental/hilar vessel injury, >25% devascularization | NOM + SAE or surgery |
| V | Shattered spleen or hilar vascular injury | Surgery (splenectomy) unless stabilized |

**Grade I**: subcapsular hematoma < 10% surface area; capsular laceration < 1 cm depth. **Grade II**: subcapsular hematoma 10-50%; parenchymal laceration 1-3 cm depth. **Grade III**: subcapsular hematoma > 50% or expanding; parenchymal laceration > 3 cm depth. **Grade IV**: laceration involving segmental or hilar vessels with major devascularization (> 25%). **Grade V**: shattered spleen or hilar vascular injury with complete devascularization. Higher grades and the presence of **contrast extravasation or pseudoaneurysm** on CTA increase the role for SAE.

## Indications for Splenic Artery Embolization

**Active extravasation** on CTA in a hemodynamically stable patient. **Pseudoaneurysm** identified on CTA regardless of injury grade. **High-grade injuries (AAST III-V)** in hemodynamically stable or stabilized patients. **Ongoing transfusion requirements** despite resuscitation in patients who are not surgical candidates. Some centers use SAE for all grade III-V injuries to improve NOM success rates. **Hemodynamic instability refractory to resuscitation** remains an indication for splenectomy, not embolization.

![Splenic injury grading and management algorithm](images/splenic-injury-algorithm.png)

## Embolization Techniques

### Proximal Splenic Artery Embolization

Coil or plug placement in the **main splenic artery** (typically mid-body, distal to the dorsal pancreatic artery). Reduces perfusion pressure while maintaining splenic viability through collateral flow (short gastric, left gastroepiploic arteries). **Preserves immunologic function** in the majority of patients. Technically faster and simpler than selective embolization. Appropriate for diffuse injuries or multiple sites of hemorrhage.

### Distal (Selective) Embolization

Superselective catheterization of the specific **bleeding intrasplenic branch**. Coil embolization at the site of extravasation or pseudoaneurysm. **Preserves more splenic parenchyma** and blood flow to uninjured segments. Technically more demanding; requires microcatheter access. Appropriate for focal injuries with a single identifiable bleeding source.

### Combined Proximal and Distal

Some centers employ a **combination approach** for high-grade injuries. Selective embolization of the bleeding source followed by proximal coil to reduce rebleeding risk. May offer the best combination of hemostasis and splenic preservation.

## Procedure Details

**Common femoral artery access** with 5F sheath. **Celiac arteriography** to evaluate splenic artery anatomy and identify bleeding sites. Selective splenic arteriography with DSA to confirm CTA findings. Advance **microcatheter coaxially** for selective or superselective embolization. Deploy **coils (microcoils for distal, standard coils or plugs for proximal)**. **Completion angiography** to confirm cessation of extravasation and preserved splenic perfusion. Sheath removal with closure device or manual compression.

![Proximal vs. distal splenic artery embolization approaches](images/splenic-embolization-techniques.png)

## Outcomes

NOM with SAE success rate: **85-95%** for all grades combined. SAE reduces NOM failure rate from approximately 20-30% to 5-10% in high-grade injuries. **Splenic salvage rate**: > 90% when SAE is performed appropriately. Rebleeding rate after SAE: 5-10%; requires repeat angiography or surgery. Overall mortality from splenic injury with appropriate management: 5-10%.

## Complications of SAE

**Splenic infarction**: occurs in 20-30% of cases; usually segmental and clinically well tolerated. **Splenic abscess**: 3-5%; managed with percutaneous drainage and antibiotics. **Post-embolization syndrome**: fever, left upper quadrant pain, leukocytosis; self-limited in most cases. **Rebleeding**: may require repeat embolization or splenectomy. **Complete splenic infarction/loss**: rare with proximal embolization; consider vaccination if occurs.

## Splenectomy: When Surgery Is Necessary

**Hemodynamic instability** refractory to resuscitation. **Grade V shattered spleen** with hilar disruption. **Failed NOM or SAE**: ongoing hemorrhage despite embolization. **Associated injuries** requiring emergent laparotomy. Post-splenectomy patients require **vaccination** against encapsulated organisms: pneumococcus, meningococcus, Haemophilus influenzae type b (ideally 14 days post-splenectomy).

## Post-Procedure Monitoring

**ICU admission** for serial hemoglobin monitoring (every 6 hours for 24-48 hours). Bed rest with activity restriction for **24-72 hours** post-embolization. Repeat CTA if clinical deterioration or falling hemoglobin. **Follow-up imaging** at 48-72 hours for high-grade injuries. Activity restriction for **6-8 weeks** after high-grade splenic injury.

![Post-SAE monitoring and follow-up protocol](images/post-sae-monitoring.png)

## Key Clinical Pearls

Splenic artery embolization significantly improves NOM success rates for high-grade splenic injuries. Proximal embolization reduces perfusion pressure while preserving splenic function via collateral flow. Selective embolization is preferred for focal injuries when technically feasible. Post-embolization splenic infarction is common but usually well tolerated and clinically insignificant. Hemodynamic instability refractory to resuscitation mandates splenectomy, not embolization.

## References

1. Stassen NA, Bhullar I, Cheng JD, et al. Selective Nonoperative Management of Blunt Splenic Injury: An Eastern Association for the Surgery of Trauma Practice Management Guideline. *Journal of Trauma and Acute Care Surgery*. 2012;73(5 Suppl 4):S294-S300.
2. Bhullar IS, Frykberg ER, Siragusa D, et al. Selective Angiographic Embolization of Blunt Splenic Traumatic Injuries in Adults Decreases Failure Rate of Nonoperative Management. *Journal of Trauma and Acute Care Surgery*. 2012;72(5):1127-1134.
3. Defined the Core Competencies. Defined the Practice Standards. *AAST Organ Injury Scaling 2018 Update*. *Journal of Trauma and Acute Care Surgery*. 2018;85(6):1119-1122.
4. Defined the Core Practice Guidelines. Defined the Core Clinical Practice Standards. *Western Trauma Association Guidelines: Blunt Splenic Injury*. 2021.