Three months after EVAR, surveillance CT angiography shows contrast extravasating at the junction between two overlapping stent-graft components, with rapid sac re-expansion. Which endoleak type is this and why does it demand urgent intervention?

• A Type II, because branch vessel backflow always causes rupture
• B Type III, a graft failure or component separation that directly pressurises the sac ✓
• C Type IV, caused by graft wall porosity and self-limiting
• D Type I, caused by retrograde flow from the inferior mesenteric artery

Explanation

Type III endoleak arises from structural graft failure, fabric tear or separation between modular components, producing direct systemic pressurisation of the aneurysm sac with high rupture risk, hence urgent repair. Type I occurs at attachment sites, not between components. Type II is backfilling from branch vessels such as the inferior mesenteric or lumbar arteries and is usually managed conservatively unless the sac enlarges. Type IV is peri-procedural porosity.

Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.