An abdominal aortic aneurysm (AAA) is a weakening and expansion of the aorta, the main blood vessel in the body. Large aneurysms are rare but can be very serious; there is a risk that the wall of the aorta will rupture which can be fatal. Approximately 6,000 people in England and Wales die every year from ruptured AAAs; men are approximately six times more likely to have an AAA than women and the chance of having an aneurysm increases with age