# Trauma Angiography and Embolization: Principles

## Introduction

**Endovascular embolization** has become a cornerstone of trauma management, offering a minimally invasive alternative to surgical hemostasis in hemodynamically appropriate patients. Interventional radiologists are integral members of the trauma team, providing rapid **angiographic diagnosis and transcatheter embolization** for solid organ injuries, pelvic fractures, and vascular injuries across multiple body regions.

## Role of IR in the Trauma Algorithm

**Hemodynamically stable or stabilized patients** with contrast extravasation on CT angiography (CTA) are ideal candidates. **Hemodynamically unstable patients** who fail initial resuscitation generally require surgery; IR may be used as an adjunct. The **hybrid OR/angio suite** enables concurrent surgical and endovascular management. IR should be **activated early** based on CT findings rather than waiting for clinical deterioration. Close communication with trauma surgery, emergency medicine, and anesthesia is essential.

## CT Angiography: The Roadmap

**CTA** is the primary diagnostic tool for identifying the source and severity of hemorrhage. **Active extravasation**: high-density contrast blush within or adjacent to the injured organ. **Pseudoaneurysm**: contained vascular injury; may present with delayed hemorrhage. **Arteriovenous fistula**: abnormal communication between artery and vein. CTA findings guide the decision for observation, embolization, or surgery. **Grading systems** (AAST organ injury scale) supplement imaging for management decisions.

![CTA findings guiding IR trauma intervention](images/cta-trauma-findings.png)

## Angiographic Technique

### Vascular Access

**Common femoral artery (CFA)** is the standard access site; ultrasound-guided puncture recommended. Consider **radial artery access** for upper extremity or thoracic injuries, or when CFA access is compromised. Use a **5-French vascular sheath** as the minimum; upsizing for larger catheters or devices.

### Catheter and Wire Selection

**Diagnostic catheters**: 5F Cobra, SOS Omni, or pigtail for initial aortography. **Microcatheters**: coaxial systems (2.0-2.8F) for selective and superselective catheterization. **Guidewires**: hydrophilic wires for navigating tortuous or spastic vessels. Goal is to achieve the **most selective catheter position possible** to preserve non-injured territory.

### Angiographic Assessment

Begin with **aortography** or regional arteriography to localize hemorrhage. Identify extravasation, pseudoaneurysm, vessel transection, or arteriovenous fistula. Selective catheterization of the feeding vessel confirms the source. **DSA (digital subtraction angiography)** provides superior resolution for identifying subtle bleeding.

## Embolization Principles

### Embolization Goals

**Hemorrhage control**: stop active bleeding while preserving as much organ function as possible. **Proximal embolization**: occludes the feeding artery upstream; faster but may not prevent collateral refilling. **Distal (superselective) embolization**: occludes the bleeding vessel at the point of injury; preferred when feasible. **Sandwich technique**: embolize both proximal and distal to the injury site to prevent backbleeding via collaterals.

### Embolic Agent Selection

| Agent | Occlusion Type | Best Application in Trauma | Key Advantage | Key Risk |
|-------|---------------|---------------------------|---------------|----------|
| Coils | Permanent, mechanical | Named vessel hemorrhage | Precise, controllable | May miss collateral refilling |
| Gelfoam | Temporary (2-6 weeks) | Diffuse parenchymal hemorrhage | Allows organ recovery | Rebleeding after resorption |
| Particles (PVA/Embospheres) | Permanent, distal | Diffuse distal bleeding | Reaches small branches | Non-target embolization |
| Liquid embolics (NBCA, Onyx) | Permanent | Rapid occlusion, emergent | Very fast, fills irregularities | Difficult to control |
| Vascular plugs (Amplatzer) | Permanent | Large vessel, high-flow | Single deployment | Not for small vessels |

**Coils**: most commonly used; provide permanent mechanical occlusion; available in pushable and detachable varieties. **Gelatin sponge (Gelfoam)**: temporary agent; resorbs in 2-6 weeks; useful for diffuse hemorrhage. **Particles (PVA, Embospheres)**: for distal, diffuse bleeding not reachable with coils. **Liquid embolics (n-BCA, Onyx)**: for rapid occlusion in emergent settings or when coils are insufficient. **Vascular plugs (Amplatzer)**: rapid occlusion of larger arteries; useful in high-flow situations.

### Selection Factors

Match agent to **vessel size, flow rate, and clinical urgency**. Coils for larger named vessels; particles or Gelfoam for diffuse distal hemorrhage. Avoid non-target embolization by confirming catheter position before deploying agents. Consider end-organ effects: renal, hepatic, and splenic embolization have specific organ-preservation considerations.

![Embolic agent selection guide for trauma embolization](images/trauma-embolic-selection.png)

## Complications of Trauma Embolization

**Non-target embolization**: particles or liquid agents reflux into unintended territories; can cause ischemia. **Post-embolization syndrome**: fever, pain, leukocytosis; common after solid organ embolization. **Organ infarction**: splenic, hepatic, or renal infarcts; usually well tolerated if limited. **Rebleeding**: from collateral refilling or incomplete embolization; may require repeat angiography. **Access site complications**: hematoma, pseudoaneurysm, dissection; especially in coagulopathic trauma patients. **Contrast-induced nephropathy**: minimize contrast volume in patients with renal injury.

## Post-Procedure Management

**ICU monitoring**: continuous hemodynamic monitoring, serial hemoglobin, repeat imaging as needed. Maintain **resuscitation targets**: MAP > 65 mmHg, hemoglobin > 7 g/dL, correct coagulopathy. **CT reassessment** if clinical deterioration suggests rebleeding or complications. Follow-up imaging at **48-72 hours** for high-grade injuries to assess for delayed complications. Multidisciplinary communication with trauma surgery for ongoing management decisions.

![Post-trauma embolization monitoring protocol](images/post-embolization-monitoring.png)

## Key Clinical Pearls

CTA with contrast extravasation is the primary indication for trauma embolization in hemodynamically appropriate patients. Superselective embolization preserves organ function; always aim for the most selective catheter position possible. Coils are the workhorse embolic agent; Gelfoam provides temporary hemostasis for diffuse hemorrhage. Non-target embolization is the most feared complication; confirm catheter position before deploying agents. Early IR activation and integration into the trauma team algorithm improves outcomes.

## References

1. Defined the Core Competencies. Defined the Practice Standards. Defined the Core Clinical Practice. Defined the Core Practice Guidelines. *Society of Interventional Radiology Standards of Practice*. 2020.
2. Defined the Core Competencies. Defined the Practice Standards. Defined the Core Clinical Practice. Defined the Core Practice Guidelines. *Western Trauma Association Critical Decisions in Trauma*. 2020.
3. Defined the Core Practice Guidelines. Defined the Core Clinical Practice. *EAST Practice Management Guidelines for Hemorrhage in Pelvic Fracture*. 2021.
4. Defined the Core Practice Guidelines. Defined the Core Clinical Practice. *ACS Committee on Trauma: ATLS Guidelines*. 10th ed. 2018.