An aneurysm is a thinning and bulging of a blood vessel wall. Abdominal aortic aneurysms (AAAs) are the most common and deadly form. Ninety-five per cent of all AAAs occur in the aorta (main artery coming off the heart) right below the arteries to the kidneys.
AAAs are most common in older adults with atherosclerosis weakening the blood vessel walls. Aortic aneurysms can be congential (present at birth). Or they can develop as a result of weight-lifting or other trauma.
A false aneurysm means there is blood leaking and trapped between two layers of the blood vessel walls. Blood vessels have three layers. Trauma or injury can puncture an artery and cause the layers to separate. With every beat of the heart, blood is forced between two layers causing a mass to form.