This factsheet is for people who have an abdominal aortic aneurysm (AAA), or who would like information about it.

AAA is a widening or bulging of the aorta (the largest blood vessel) in the abdomen. AAA usually occurs at a weak spot in the aortic wall. It often doesn’t cause any symptoms, but if the aneurysm widens rapidly it may cause abdominal pain which can be severe. If it bursts (ruptures) this can be fatal.

About abdominal aortic aneurysm

The aorta is the largest artery in your body. It carries all the blood that is pumped out of your heart and distributes it, via its many branches, to all the organs of your body. The aorta passes upwards from your heart before curving backwards and downwards and travelling through your chest (the thoracic aorta) and into your abdomen (the abdominal aorta).

The aorta is usually 2 to 3cm (about one inch) in diameter. A weak spot in the aorta can cause it to bulge outwards (called an aneurysm). If the bulge occurs in the aorta as it goes through your chest, it’s called a thoracic aortic aneurysm. For more information about thoracic aortic aneurysm see the health factsheet. If it occurs in the aorta as it goes through your abdomen, it’s called an abdominal aortic aneurysm (AAA). AAAs are more common than thoracic aneurysms.

The chance of an aneurysm rupturing depends on its size. If your aneurysm is greater than 5.5cm wide the chances of rupture are high – and the risk increases with increasing size.

Symptoms of abdominal aortic aneurysm

AAA often causes no symptoms. However, if it starts to expand and push on surrounding tissue or nerves in your abdomen, it can cause abdominal pain and/or lower back pain.

Complications of abdominal aortic aneurysm

If the aneurysm ruptures it causes severe internal bleeding and can be fatal without emergency surgery to repair it. The risk of an aneurysm rupturing increases as it gets wider.

Causes of abdominal aortic aneurysm

The main cause of AAA is atherosclerosis. This is a process in which fatty deposits build up on the inside of your arteries and weaken the artery walls.

You are more likely to develop atherosclerosis, and therefore an aneurysm, if you:

are male (AAAs are about three times more common in men than in women) smoke are over 50 have a family history of AAA

have high blood pressure do little physical activity have high cholesterol are overweight

Your risk of having an aneurysm also increases if you have Marfan’s syndrome.

Diagnosis of abdominal aortic aneurysmAortic aneurysms often don’t have any symptoms, unless they are large or are expanding quickly. Your GP may only suspect you have an aortic aneurysm following a routine examination.

When your doctor examines you, he or she may feel a pulsating mass in your abdomen which may be tender if your AAA is large. If your doctor suspects an AAA, you may have other tests in hospital, including the following.

Ultrasound scan – this provides a clear image of the abdominal aorta and can help to identify an aneurysm and measure its size.

CT or MRI scan – these provide a detailed three-dimensional image of the abdominal aorta and are very useful for determining the exact position of the aneurysm.


You may be invited to be screened for an abdominal aortic aneurysm at your GP surgery or local hospital if you’re a man over 65. Speak to your GP for more information.

Treatment of abdominal aortic aneurysm

Your treatment for an AAA will depend on your symptoms and the size of your aneurysm.

Watchful waiting

If you have a small aneurysm, surgery isn’t usually advised but you will need regular ultrasound checks to see if your aneurysm is expanding. It’s also important to manage your condition by changing your lifestyle and treat any condition that may be causing the aneurysm (such as high blood pressure).


Elective or planned surgery is often advised if your aneurysm is:

larger than 5.5cm expanding by more than 1cm per year causing you pain

Emergency (life-saving) surgery is needed if your aneurysm ruptures.

There are two main surgical options for AAA. Both are usually performed under a general anaesthetic. This means you will be asleep during the operation.

Open surgery

This is the traditional method of treating aneurysms. It’s a major operation in which your surgeon opens your abdomen to access the aorta and inserts a graft into the weak area of the aorta. The graft can be either a piece of blood vessel taken from another place in your body or it can be synthetic. A synthetic graft is made out of an elastic material and is similar to your normal healthy aorta. The blood flows through the graft inside the aorta instead of going through the aneurysm and prevents the aneurysm getting bigger. For more information see the health factsheet on open surgery for aortic aneurysm.

The operation can be done using keyhole surgery. Keyhole surgery is less invasive and involves making two or three small cuts on your abdomen. Your surgeon will insert a tube-like telescopic camera, which will send pictures to a monitor so he or she can see the aneurysm. Your surgeon will put the graft into place using specially designed surgical instruments that will be passed through the other cuts. However, keyhole surgery isn’t suitable for everybody.

Endovascular stent graft replacement

Sometimes aneurysms can be treated using a new procedure called endovascular stent graft replacement (or endovascular aneurysm repair, EVAR). A stent – a tube that is covered with synthetic graft material – is fed through the femoral arteries in your groin up though the aorta to the area of the aneurysm. Your surgeon uses X-ray images to guide the placement of the stent. The graft material bonds with the arterial wall and the blood flows through the stent instead of the weakened aneurysm. However, stents aren’t suitable for everyone – it depends on the location of the aneurysm and other factors. For more information see the health factsheet on endovascular aneurysm repair.

This procedure is undertaken with general anaesthesia and will be discussed with your anaesthetist before surgery is carried out- a stay in HDU (high dependency unit) or ITU (intensive therapy unit) is dependant on your medical needs and your recovery from the procedure which will be based on your progress throughout the operation.

Prevention of abdominal aortic aneurysm

There are several things you can do to reduce your chance of developing atherosclerosis and therefore an aneurysm:

not smoking having your blood pressure and cholesterol checked regularly exercising regularly maintaining a healthy weight eating a healthy diet

You should also have regular medical check-ups if you have a family history of arterial disease so that any problems can be detected early.

Abdominal aortic aneurysm

Abdominal aortic aneurysm