Which option correctly pairs an endoleak type with its description?

• A. Type II – retrograde flow from collateral vessels
• B. Type I – leak at the proximal/distal seal
• C. Type III – graft fabric/connection failure
• D. Type IV – graft porosity (rare)

Answer: (B)

Endoleaks after EVAR are distinguished by how blood continues to enter the aneurysm sac. The correct pairing is a leak at the proximal or distal seal, which is a Type I endoleak. When the graft’s attachment seal isn’t complete, blood flows directly into the sac under systemic pressure, keeping the aneurysm pressurized and raising rupture risk, so it typically requires urgent intervention to restore a proper seal or replace the graft.

The other descriptions correspond to different mechanisms: a Type II endoleak comes from retrograde flow through collateral vessels into the sac; a Type III endoleak results from a leak through the graft fabric or at modular connections; and a Type IV endoleak reflects graft porosity, a rare early occurrence with modern devices.