After endovascular aneurysm repair, contrast outside the graft but inside the sac is an endoleak: type I (seal zone) and III (graft defect) need urgent repair; type II (branch backflow) is watched unless the sac grows.
Orient first
- Types: I (proximal/distal seal), II (lumbar/IMA backflow — commonest), III (junction/fabric), IV (porosity), V (endotension — sac growth without visible leak).
- Sac diameter change over time matters more than the leak type in type II.
- A delayed phase is needed — slow type II leaks appear late.
Acquire the study
- Unenhanced, arterial and delayed phases, 1 mm with MPR.
The manoeuvre
- Maximal sac diameter in mm perpendicular to the centre line — compare with prior.
- Unenhanced vs post-contrast: new density in the sac = leak (not calcium).
- Arterial phase: leak at the seal zones or graft junctions (type I/III).
- Delayed phase: leak fed by lumbar arteries or the IMA (type II).
- Graft migration, limb kinking or occlusion.
What confirms it
- Contrast in the sac outside the graft with its source; sac growth over time.
What licenses you to exclude it
- No contrast outside the graft on arterial and delayed phases with a stable or shrinking sac.
The classic misread
- Calling calcification in the thrombus a leak without the unenhanced series.