# Hepatic and Renal Trauma Embolization

## Introduction

The liver and kidneys are among the most commonly injured solid organs in abdominal trauma. **Non-operative management (NOM)** is the standard for hemodynamically stable patients, with **transcatheter arterial embolization (TAE)** serving as a critical adjunct to improve NOM success rates. Understanding the vascular anatomy, injury patterns, and embolization techniques specific to each organ is essential for the interventional radiologist.

## Hepatic Trauma

### Anatomy

**Dual blood supply**: hepatic artery (25-30% of blood flow) and portal vein (70-75%). The **common hepatic artery** arises from the celiac trunk and gives rise to the proper hepatic artery, which bifurcates into right and left hepatic arteries. Variant anatomy is common: replaced or accessory right hepatic artery from SMA (15-20%), replaced left hepatic artery from left gastric artery (10-15%). Understanding variant anatomy is critical for complete angiographic evaluation.

### AAST Liver Injury Scale

| Grade | Description | Management |
|-------|-------------|------------|
| I | Subcapsular hematoma <10% surface; laceration <1 cm depth | Conservative |
| II | Subcapsular hematoma 10-50%; laceration 1-3 cm depth | Conservative |
| III | Laceration >3 cm depth; subcapsular hematoma >50% | NOM +/- embolization |
| IV | Parenchymal disruption 25-75% of lobe; active hemorrhage | Embolization or surgery |
| V | Parenchymal disruption >75% of lobe; juxtahepatic venous injury | Surgery or embolization |

Grades III-V with CTA extravasation or pseudoaneurysm are candidates for embolization.

### Embolization Technique

**Celiac arteriography** followed by selective hepatic arteriography. Identify bleeding branch and advance microcatheter to the bleeding site. **Superselective embolization** is preferred to preserve hepatic parenchyma. **Embolic agents**: microcoils for named branches; Gelfoam for diffuse hemorrhage. The dual blood supply of the liver provides a safety margin; hepatic artery embolization is generally well tolerated. **Completion angiography** must include evaluation for variant anatomy sources of hepatic blood supply.

![Hepatic trauma embolization technique and anatomy](images/hepatic-trauma-embolization.png)

### Complications of Hepatic Embolization

**Hepatic infarction**: usually well tolerated due to portal venous supply; may cause transient LFT elevation. **Liver abscess**: 1-3%; risk increases with large areas of devitalized tissue; managed with percutaneous drainage. **Biloma**: bile collection from ductal injury; managed with percutaneous drainage and possible ERCP. **Gallbladder ischemia**: if the cystic artery is inadvertently embolized. **Re-bleeding**: 5-10%; may require repeat embolization or surgery.

### Special Hepatic Considerations

**Hepatic pseudoaneurysm**: may present with delayed hemorrhage (days to weeks); requires embolization even if asymptomatic. **Hemobilia**: GI bleeding from communication between hepatic artery and biliary tree; classic triad of RUQ pain, jaundice, and GI bleeding. **Arterioportal fistula**: abnormal communication between hepatic artery and portal vein; may cause portal hypertension.

## Renal Trauma

### Anatomy

**Renal arteries** arise from the aorta at L1-L2; typically single but accessory arteries present in 25-30%. **Segmental arteries** are end arteries with no significant collateral supply. The kidney is less tolerant of embolization than the liver; superselective technique is critical.

### AAST Kidney Injury Scale

**Grade I**: contusion or non-expanding subcapsular hematoma. **Grade II**: non-expanding perinephric hematoma; laceration < 1 cm depth without collecting system injury. **Grade III**: laceration > 1 cm without collecting system injury. **Grade IV**: laceration into collecting system; segmental renal artery or vein injury with hemorrhage; segmental infarction. **Grade V**: shattered kidney; main renal artery or vein avulsion/thrombosis.

### Indications for Renal Embolization

**Active extravasation** on CTA in a hemodynamically stable patient. **Pseudoaneurysm or arteriovenous fistula** identified on CTA. **Persistent or delayed hematuria** with identifiable vascular injury. **Grade IV-V injuries** with arterial hemorrhage in patients being managed non-operatively. Hemodynamic instability with renal source refractory to resuscitation may require nephrectomy.

### Embolization Technique

**Aortography** to assess bilateral renal arteries and identify accessory vessels. Selective renal arteriography followed by **superselective microcatheter** advancement. **Microcoil embolization** of the specific bleeding segmental or subsegmental artery. Minimize the volume of infarcted parenchyma; every nephron counts. Gelfoam may be used as an adjunct for diffuse hemorrhage within a segment. **Avoid proximal main renal artery embolization** unless the kidney is unsalvageable.

![Renal trauma embolization superselective technique](images/renal-trauma-embolization.png)

### Complications of Renal Embolization

**Renal infarction**: expected consequence of segmental embolization; minimize volume. **Loss of renal function**: risk is proportional to the volume of embolized parenchyma. **Post-embolization syndrome**: flank pain, fever; managed supportively. **Renal abscess**: rare; managed with percutaneous drainage. **Hypertension**: Page kidney (compression of renal parenchyma by hematoma) or renal artery stenosis from injury.

## Post-Procedure Management for Both Organs

**ICU monitoring**: serial hemoglobin, vitals, urine output. **Repeat CTA** at 48-72 hours for high-grade injuries. Monitor for **delayed pseudoaneurysm formation** (weeks after injury). Hepatic injuries: follow LFTs, monitor for biloma and abscess. Renal injuries: follow creatinine, monitor for hypertension and delayed urinoma.

![Hepatic and renal trauma management decision algorithm](images/hepatic-renal-trauma-algorithm.png)

## Key Clinical Pearls

Superselective embolization is the goal for both hepatic and renal trauma to preserve maximum parenchyma. The liver tolerates embolization well due to dual blood supply; the kidney is less forgiving as segmental arteries are end arteries. Variant hepatic arterial anatomy must be identified to avoid missing a bleeding source. Delayed pseudoaneurysm is a recognized complication of both hepatic and renal injuries; follow-up imaging is essential. Non-operative management with adjunctive embolization is the standard for hemodynamically stable solid organ injuries.

## References

1. Defined the Core Practice Guidelines. *AAST Organ Injury Scaling 2018 Update*. *Journal of Trauma and Acute Care Surgery*. 2018;85(6):1119-1122.
2. Defined the Core Practice Guidelines. Defined the Clinical Standards. *EAST Practice Management Guidelines: Non-operative Management of Blunt Hepatic Injury*. 2012.
3. Defined the Core Clinical Practice. Defined the Practice Standards. *Morey AF et al. AUA Uropelvic Guidelines for Renal Trauma*. *Journal of Urology*. 2014;192(2):316-324.
4. Defined the Core Competencies. Defined the Practice Standards. *SIR Guidelines for Trauma Embolization*. 2020.