An Abdominal Aortic Aneurysm (AAA) is a condition in which weakening of the lining in the aorta causes the aorta to expand in diameter. Abdominal aortic aneurysms pose a threat because they are usually silent until a medical emergency occurs.
The abdominal aorta is the largest blood vessel in the body and the main artery that originates in the heart. As the lining weakens from age and other risk factors, the vessel wall thins and expands. The most common location for an AAA is between where the aorta divides to supply blood to the kidneys and where it divides to supply blood to the pelvis and legs.