Abdominal aortic aneurysm (AAA or triple A) is a localized enlargement of the abdominal aorta such that the diameter is greater than 3 cm or more than 50% larger than normal. They usually cause no symptoms, except during rupture.An enlargement of the aorta, the main blood vessel that delivers blood to the body, at the level of the abdomen.An abdominal aortic aneurysm (AAA) can be life-threatening if it bursts. Abdominal aortic aneurysms are most common in older men and smokers.An AAA often grows slowly, without symptoms. As it grows, some people may notice a pulsating feeling near the navel. Pain in the back, stomach or side may be signs of impending rupture.Stopping smoking may slow their growth. Small ones may only need monitoring. Aneurysms that are too large or growing too quickly should be repaired with surgery.