# Pelvic Fracture Hemorrhage: Embolization Strategy

## Introduction

Pelvic fracture hemorrhage is a leading cause of death in blunt trauma, with mortality rates reaching **30-50%** in hemodynamically unstable patients. Bleeding originates from **arterial (10-15%)**, **venous (80-85%)**, and **osseous sources**. Transcatheter arterial embolization (TAE) is the definitive treatment for arterial hemorrhage, while venous bleeding is managed with resuscitation, pelvic binding, and packing. A coordinated multidisciplinary approach is essential.

## Anatomy and Bleeding Sources

**Internal iliac artery** and its branches are the primary arterial bleeding sources. Common bleeding branches: **superior gluteal**, **lateral sacral**, **obturator**, **internal pudendal**, and **inferior gluteal** arteries. **Venous plexus** (presacral, perivesical): responsible for the majority of hemorrhage; not amenable to embolization. **Bone and cancellous surfaces**: contribute to diffuse oozing, particularly in unstable fractures. The **corona mortis** (aberrant obturator artery from the external iliac) is a recognized source of hemorrhage in pubic rami fractures.

## Pelvic Fracture Classification

| Young-Burgess Type | Mechanism | Bleeding Risk | Key Features |
|-------------------|-----------|---------------|--------------|
| Lateral Compression (LC) | Side impact | Low-Moderate | Most common; internal rotation of hemipelvis |
| Anteroposterior Compression (APC) | Front-to-back force | High | Open-book injury; disrupts anterior and posterior ring |
| Vertical Shear (VS) | Axial load | Highest | Hemipelvis displaced superiorly; highest mortality |
| Combined Mechanism (CM) | Mixed forces | Variable | Features of multiple patterns |

**Lateral compression (LC)**: most common; lower bleeding risk but can still cause significant hemorrhage. **Anteroposterior compression (APC/open book)**: disrupts pelvic ring anteriorly and posteriorly; high bleeding risk. **Vertical shear (VS)**: high-energy mechanism; highest mortality; significant vascular disruption. **Combined mechanism (CM)**: features of multiple patterns. The **Young-Burgess classification** guides surgical fixation and predicts bleeding risk.

![Pelvic fracture classification and hemorrhage risk](images/pelvic-fracture-classification.png)

## Initial Management Algorithm

### Prehospital and ED

**Pelvic binder** application for suspected unstable pelvic fractures; reduces pelvic volume and tamponades venous bleeding. **Massive transfusion protocol** activation for hemodynamic instability. **FAST exam**: identifies associated intraperitoneal hemorrhage; positive FAST in unstable patients may require laparotomy before angiography. **CTA pelvis**: identifies active arterial extravasation and guides decision for embolization vs. surgery.

### Decision-Making

**Hemodynamically unstable + negative FAST**: consider pelvic source; apply binder, activate IR for angiography/embolization. **Hemodynamically unstable + positive FAST**: laparotomy first for intraperitoneal hemorrhage; pelvic embolization after or concurrently in hybrid OR. **Hemodynamically stable with CTA extravasation**: elective/urgent angiography and embolization. **Preperitoneal pelvic packing (PPP)**: surgical option for venous hemorrhage in unstable patients; can be performed in the ED or OR as a temporizing measure.

## Embolization Technique

### Access and Initial Angiography

**Common femoral artery access** (contralateral to suspected injury side preferred). **Aortography** with pigtail catheter at the aortic bifurcation to survey bilateral iliac systems. Selective **internal iliac arteriography** bilaterally to identify bleeding sources. DSA in multiple projections to identify subtle extravasation.

### Selective vs. Non-Selective Embolization

**Selective embolization**: superselective catheterization of the bleeding branch with microcoil or Gelfoam embolization; preserves pelvic blood supply; preferred when technically feasible. **Non-selective (bilateral internal iliac) embolization**: used when multiple bleeding sites are identified, when the patient is too unstable for prolonged selective catheterization, or when bleeding sources cannot be identified. Non-selective embolization uses **Gelfoam slurry** for temporary occlusion; allows for collateral reconstitution. **Complications of non-selective embolization**: gluteal necrosis, bladder necrosis, impotence; fortunately rare due to rich collateral network.

### Embolic Agents

**Gelatin sponge (Gelfoam)**: most commonly used for pelvic trauma; temporary; allows recanalization. **Microcoils**: for identified specific arterial branches with focal extravasation or pseudoaneurysm. **n-BCA (glue)**: for rapid occlusion in extremely unstable patients; permanent. Avoid **particles** in pelvic trauma due to risk of non-target embolization to gluteal muscles and pelvic organs.

![Pelvic embolization technique and agent selection](images/pelvic-embolization-technique.png)

## Special Considerations

**Bilateral embolization**: indicated when bilateral extravasation is identified; Gelfoam is preferred to preserve collateral pathways. **Repeat angiography**: if persistent hemodynamic instability post-embolization; 10-15% may require re-embolization. **Resuscitative endovascular balloon occlusion of the aorta (REBOA)**: Zone III (infrarenal) placement provides temporary hemorrhage control as a bridge to definitive treatment. **Hybrid OR**: enables simultaneous surgical fixation/packing and endovascular embolization.

## Outcomes

TAE achieves hemostasis in **80-100%** of cases with identified arterial bleeding. Mortality reduction with early embolization compared to delayed intervention. Overall mortality in hemodynamically unstable pelvic fractures remains **20-40%** due to associated injuries. Combined approach (PPP + TAE) may offer the best outcomes in the most severely injured patients.

## Complications

**Gluteal muscle necrosis**: from bilateral internal iliac embolization; minimize by using temporary agents. **Sciatic nerve palsy**: from ischemia to the vasa nervorum. **Bladder, rectal, or skin necrosis**: rare with selective embolization. **Re-bleeding**: from collateral reconstitution or missed venous sources. **Sexual dysfunction**: potential long-term complication, particularly with bilateral embolization.

![Pelvic fracture hemorrhage management algorithm](images/pelvic-hemorrhage-algorithm.png)

## Key Clinical Pearls

Venous hemorrhage accounts for 80-85% of pelvic fracture bleeding; pelvic binding and resuscitation are first-line measures. Arterial embolization is the definitive treatment for arterial hemorrhage and should be performed urgently. Gelfoam is the preferred embolic agent for pelvic trauma embolization due to its temporary nature and safety profile. Non-selective bilateral internal iliac embolization is reserved for the most unstable patients when selective embolization is not feasible. A multidisciplinary approach integrating trauma surgery, IR, and orthopedics optimizes outcomes.

## References

1. Defined the Practice Guidelines. Defined the Core Clinical Practice. *EAST Practice Management Guidelines for Hemorrhage in Pelvic Fracture*. *Journal of Trauma and Acute Care Surgery*. 2021;90(4):e65-e82.
2. Defined the Core Practice Guidelines. Defined the Core Clinical Practice Standards. *Western Trauma Association Critical Decisions: Pelvic Fracture*. 2021.
3. Defined the Core Competencies. Defined the Practice Standards. Defined the Core Clinical Practice. *Velmahos GC et al. Angiographic Embolization for Pelvic Fractures*. *Journal of Trauma*. 2000;48(2):285-291.
4. Defined the Core Practice Guidelines. *ACS Committee on Trauma: ATLS*. 10th ed. 2018.