An abdominal aortic aneurysm is an enlarged area in the lower part of the body's main artery, called the aorta. The aorta runs from the heart through the center of the chest and belly area, called the abdomen. The aorta is the largest blood vessel in the body. An abdominal aortic aneurysm that ruptures can cause life-threatening bleeding. Treatment depends on the size of the aneurysm and how fast it's growing. Treatment varies from regular health checkups and imaging tests to emergency surgery.