Abdominal aortic aneurysm (AAA), abnormal focal dilation of the abdominal aorta, is a life-threatening condition that requires monitoring or treatment depending upon the size of the aneurysm and/or symptomatology. AAA may be detected incidentally or at the time of rupture. An arterial aneurysm is defined as a permanent localized dilatation of the vessel by at least 150% compared to a relatively normal adjacent diameter of that artery.