Endovascular treatment of gastrointestinal bleeding

Diagnostic capabilities and prophylactic embolization

Catheter angiography has high sensitivity and is capable of detecting active bleeding if the rate of blood loss is at least 0.5 mL/min.

In situations where active bleeding is not observed at the time of the procedure, but the source is known or clinically suspected (e.g., in the setting of severe comorbidities or recent surgical/endoscopic interventions), prophylactic embolization is employed.

It is essential to consider anatomical nuances:

• In the upper gastrointestinal tract, prophylactic intervention is technically simpler and safer due to the rich vascular network.
• In the lower gastrointestinal tract, collateral blood supply is significantly poorer. Any inaccuracy can be fatal; therefore, the most rigorous and precise identification of the damaged vessel is required here to avoid severe complications, such as intestinal ischemia or infarction.

Angiographic signs of bleeding

To successfully stop blood loss, the physician must identify specific markers of vascular injury on angiograms.

Direct sign — direct extravasation (leakage) of the contrast medium beyond the vascular bed directly into the intestinal lumen. Important note: this sign may not be visualized. This occurs if the bleeding is intermittent in nature or its rate at the time of contrast injection is too low.

If direct leakage is not visible, indirect signs indicate the source with high accuracy:

• Presence of a formed pseudoaneurysm.
• Sudden cutoff or vessel truncation.
• Early venous return.
• Contrast pooling — vascular lakes.
• Pathological tumour circulation.
• Pronounced irregularity of the vascular wall contours.

Embolization techniques

Once the source of bleeding is reliably identified, vessel occlusion is performed. Embolization can serve two purposes:

1. As a standalone definitive therapeutic method (therapeutic).
2. As a means of stabilization for the patient in preparation for upcoming open surgery.

The anatomical localization of the source dictates the surgeon's choice of a specific embolizing agent, as well as the scope and extent of the intervention. This is critically important to prevent ischemic injury or infarction of the surrounding healthy tissues.

Clinical case review: lower gastrointestinal bleeding

To understand the technique, let us review the standard protocol for detecting and treating acute lower gastrointestinal bleeding.

1. CT angiography (coronal view, arterial phase): initial scan clearly demonstrating contrast media extravasation into the rectal lumen.
2. Selective angiogram of the inferior mesenteric artery (inferior mesenteric artery): the procedure is performed using a specialized reverse-curve catheter. At this stage, a pseudoaneurysm originating from the superior rectal artery (superior rectal artery) is visualized.
3. Superselective angiogram: performed via a coaxial microcatheter advanced directly to the area of interest. This allows for detailed visualization of the pseudoaneurysm and confirms the presence of active extravasation.
4. Microcoil embolization (microcoils): the final stage of treatment. A critical technical rule is that microcoils are placed both proximally and distally to the pseudoaneurysm. This technique is used to reliably prevent retrograde filling (back filling) of the aneurysm via collaterals. Result: bleeding successfully stopped.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Characteristics of collateral blood supply in the upper and lower GI tracts
• Types of embolic agents and criteria for their selection
• Technique of coaxial superselective catheterization
• Prevention of ischemic complications after endovascular interventions
• Differential diagnosis of bleeding sources based on indirect angiographic signs

Other topics in the "Interventional radiology" section

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