Abdominal aortic aneurysm involves a widening, stretching, or ballooning of the aorta. There are several causes of abdominal aortic aneurysm, but the most common results from atherosclerotic disease. As the aorta gets progressively larger over time there is increased chance of rupture.
The aorta carries oxygen-rich blood from the heart to smaller arteries throughout the body. An abdominal aneurysm occurs in the abdominal aorta, the part of the aorta between the bottom of the chest and the pelvis.
Patient education: Abdominal aortic aneurysm (Beyond the Basics) - UpToDate