How is transcatheter embolization of a gastrointestinal (GI) bleed done?

Transcatheter Embolization for Gastrointestinal Bleeding

Transcatheter arterial embolization (TAE) for gastrointestinal bleeding is performed by identifying the bleeding vessel through angiography and then selectively embolizing it with materials such as microcoils, which has a technical success rate of 98% and is the preferred approach for hemodynamically unstable patients with active bleeding that cannot be controlled endoscopically. 1

Indications and Patient Selection

TAE is indicated in the following scenarios:

• Massive GI bleeding with hemodynamic instability
• Patients who have required >5 units of blood within 24 hours
• Failed endoscopic management
• Poor surgical candidates
• Active bleeding identified on CT angiography (CTA)

TAE is particularly valuable for patients who are too ill to tolerate urgent surgery, as it provides time to stabilize the patient and prepare the bowel for potential future surgical intervention 1.

Procedure Steps

1. Diagnostic Angiography:

   • Selective catheterization of mesenteric arteries (superior and inferior mesenteric arteries for lower GI bleeding; celiac trunk for upper GI bleeding)
   • Identification of contrast extravasation indicating active bleeding
   • Technical note: Bleeding must be active during contrast injection to be visualized (≥0.5 mL/min)

2. Superselective Catheterization:

   • Microcatheter navigation to the bleeding vessel
   • Target is to reach the vasa recta (terminal branches) when possible

3. Embolization:

   • Deployment of embolic materials at the bleeding site
   • Most commonly used materials:
     • Microcoils (61% of cases) - associated with lower rebleeding rates (12% vs 36%) 1, 2
     • Gelatin sponge (17% of cases) 2
     • N-butyl cyanoacrylate (NBCA) - particularly useful in patients with coagulopathy 1, 3
     • Ethylene-vinyl alcohol copolymer - effective even in patients with coagulopathy 1

4. Confirmation of Hemostasis:

   • Post-embolization angiography to confirm cessation of contrast extravasation

Efficacy and Outcomes

• Technical success rate: 98% 1, 2
• Clinical success rate: 63-96% 1
• 30-day rebleeding rate: 11-50% 1, with an average of 23% 2
• TAE provides definitive treatment in 81-86% of patients 1

Factors Affecting Success

1. Location of bleeding:

   • Small bowel embolization has higher rebleeding rates than colonic embolization due to more robust vascular supply and collateral pathways 1

2. Underlying pathology:

   • Diverticular bleeding: 15% rebleeding rate
   • Angiodysplasia or inflammatory lesions: 45% rebleeding rate 1

3. Coagulopathy:

   • Independent predictor of rebleeding (OR = 4.37) 4
   • Should be corrected before TAE when possible
   • When correction is not possible, liquid embolic agents like NBCA are preferred 1, 3

4. Embolization technique:

   • Embolization in ≥2 territories increases rebleeding risk (OR = 4.93) 4
   • Superselective embolization of single vasa recta is preferred 1

Complications

• Major ischemic complications: 3-11% 1
• Minor ischemic injury (self-limited abdominal pain, asymptomatic serum lactic acid elevation) 1
• Specific complications:
  • Bowel ischemia: 4% 2
  • Coil migration: 3% 2
  • Hepatic artery dissection 4
  • Splenic embolization 4
  • Hepatic abscess and limb ischemia (rare) 3

Special Considerations

• Timing is critical: Delay between positive CTA/radionuclide scan and arteriography reduces success rates 1
• Empiric vs. targeted embolization: Targeted embolization (when active extravasation is seen) has similar rebleeding rates but lower mortality compared to empiric embolization (9% vs 31%) 2
• Vasopressin infusion: Alternative when diffuse bleeding source is identified or when superselective catheterization fails 3

Post-procedure Management

• Monitor for signs of rebleeding
• Surveillance for ischemic complications
• Follow-up endoscopy may reveal embolization-induced ulcers in approximately 30% of patients, which typically respond to conservative management 3

TAE is a valuable alternative to surgery for GI bleeding that is refractory to endoscopic treatment, with high technical success rates and acceptable clinical outcomes, particularly in high-risk surgical patients 5, 6.