What causes abdominal aortic aneurysm?

Medial necrosis. Cystic medial necrosis induced by arteriosclerotic obliteration of the vasa vasorum of the aorta is the most common cause.
Hypertension & genes. Genetics plus hypertension plus age.
.? AAA. They are a bulge in the wall of the aorta (your main artery running through your abdomin and ultimately supplying the blood to your legs) from a weakness. They can be thought of like a bulge in your garden hose. The exact cause is still under investigation.
Causes. Htn, smoking, hypercholesteremia, genetic factors. Males over 65 who ever smoked need screening with ultrasound.