Classification of endoleaks

Last revised by Ciléin Kearns on 23 Jan 2023

Endoleaks occur when an aneurysmal sac continues to be pressurised despite endoluminal stent placement. See the full article on endoleaks here.


There are five types:

  • type I: leak at graft ends (inadequate seal) - most common after repair of thoracic aortic aneurysms 4
    • Ia: proximal
    • Ib: distal
    • Ic: iliac occluder
  • type II: sac filling via branch vessel (e.g. lumbar or inferior mesenteric artery)
    • most common after repair of abdominal aortic aneurysms 4 (80%)
    • sometimes referred to as a "retroleak"
    • enthusiastic examiners sometimes ask for the eponymous name of the large collateral artery between the IMA and SMA = Riolan's arch
    • most spontaneously resolve and require no treatment
    • IIa: single vessel
    • IIb: two vessels or more
  • type III: leak through a defect in graft fabric (mechanical failure of graft)
    • IIIa: junctional separation of the modular components
    • IIIb: fractures or holes involving the endograft
  • type IV: a generally porous graft (intentional design of graft)
  • type V: endotension

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