The aorta is the largest artery in the body and carries blood from the heart and run down through the chest and the abdomen. Many smaller arteries come off the aorta to supply blood to all parts of the body.
An aneurysm is a blood vessel dilatation, where the artery or vein swells to an abnormal size. Aneurysms can occur in any artery but most commonly occur in the section of the aorta that passes through the abdomen and these are known as abdominal aortic aneurysms (AAA).
The normal aortic diameter is less than 3cm. Aneurysms generally take years to develop, usually growing at a rate of 1-2mm per year, and it is rare for them to give any symptoms during this time. But if an aneurysm becomes large it can sometimes cause a pulsating feeling in your abdomen or pain in your abdomen or back.
The exact reason why an aneurysm forms in the aorta is not clear in most cases. They are most common in men over the age of 65.
The main risk factors are:
Research has shown that in people with an AAA measuring less than 5.5cm it is safer not to operate. For aneurysms measuring less than 5.5cm the risk of rupture is less than one in 100 per year. As aneurysms get larger than 5.5cm the risk of rupture increases and is at the size that the option for surgery is considered.
There are two types of operations that can be done to repair an aneurysm: