The types of endoleaks after an endovascular repair of an abdominal aortic aneurysm are as follows:
- Type I is due to an incompetent seal at the proximal (Ia) or distal (Ib) attachment site.
- Type II results from flow into and out of the aneurysm sac from one or more patent branch vessels (lumbar or inferior mesenteric artery).
- Type III results from dissociation of modular components.
- Type IV is due to leaks through the porous graft material.
- Endoleak of undefined origin (type V) is continued aneurysm sac expansion without a demonstrable endoleak on any imaging modality. It is also referred to as endotension.