Abdominal Aortic Aneurysm - AAA

What is an aneurysm?

An aneurysm occurs when the walls of your arteries weaken.  The pressure of blood flow can cause it to stretch and balloon out to form an aneurysm, rather like a worn car tyre.

Aneurysms can occur in any artery. They can be small and round or long and balloon-like.  The most common artery to be affected is the aorta, which is the main artery in your tummy (abdomen). These are known as abdominal aortic aneurysms.  

The aorta is the largest blood vessel in your body.  It runs from the left side of the heart, down through the chest and into the abdomen. At about hip level, it divides into 2 arteries which deliver blood to your legs and feet (iliac arteries).

Aneurysms can affect people of any age and both sexes. However, they are most common in men, people with high blood pressure (hypertension) and those over the age of 65.

If an aneurysm reaches a size when surgically repairing it is advisable as there is a risk of it rupturing (bursting), which can lead to potentially life-threatening bleeding and even death.

If your aneurysm bursts, you may suddenly feel intense weakness, dizziness, or pain, and you may eventually lose consciousness.

What is an Abdominal Aortic Aneurysm- AAA

The normal aorta is about 16-22mm in diameter.  An abdominal aortic aneurysm is said to be present if a section of the aorta within the abdomen is 30 mm or more in diameter.

Aneurysms generally take years to develop and it is rare for them to give symptoms during this time. This condition is often found by chance during a physical examination or scan for unrelated symptoms.

Eventually they may get so large that there is a significant risk of the artery wall bursting and bleeding out into the abdomen. This is a serious emergency known as a ruptured aneurysm.

In England and Wales between 6,000 and 8,000 people each year suffer from rupture (bursting) of an abdominal aortic aneurysm. Most of these patients are men over the age of 65 years.

Why do we get aneurysms? 

The risk of developing an aneurysm appears to be dependent on your genes, so close relatives of an affected patient are more likely to get one themselves. However, most patients do not have a known family history at detection.

About 4 in 100 men over the age of 65 will develop an aneurysm, though not all will be of significant size, and about 1 in 100 will have a large aneurysm requiring surgery. They are about 6 times rarer in women.

Smoking and high blood pressure are known to increase the size and risk, of aneurysms once they are present.

AAA’s vary in size. As a rule, once you develop an AAA, it tends to gradually get larger. The speed at which it gets larger varies from person to person. However, on average, an AAA tends to get larger by about 10% per year.

How is an aneurysm diagnosed?

The diagnosis is usually made with an ultrasound scan of the abdomen, or sometimes with a CT or MRI scan. The most important feature of the scan is the maximum diameter of the aorta, which is usually about 2½ cm (1 inch) across in adults, although this varies with your build.

An aneurysm is said to be present if the artery is over 4cm across, and then the tendency is for the vessel to gradually increase over years.

Will I need an operation?

Eventually they may reach a size where surgery is indicated, usually when they exceed 5.5cm. Because surgery carries significant risks, the decision to operate must take into account the individual health of the patient, in particular the heart, lungs and kidneys. Before operating, most patients will need some sort of tests on these organs.

What operation will be performed?

Traditional surgery for aneurysm repair involves an incision in the abdomen and replacement of the affected section of vessel with a fabric tube. If the aneurysm extends into the pelvis, then a graft designed like a pair of trousers is used and may extend to the groins in some patients. The main risk of surgery is death or heart attack, and this is about 1 in 20 patients overall. However after a successful operation the risk of later complications is very low.

With modern technology, the risks of the operation can be markedly reduced by keyhole or endovascular surgery using a stent-graft, but not every patient or every aneurysm is suitable for this. In particular, aneurysms arising close to or above the kidneys are more difficult to treat in this way.

All patients treated by endovascular surgery need to be followed up postoperatively with regular scans to detect slippage or failures of the stent-graft.

What happens now?

Your surgeon will discuss whether you need an operation soon, or whether you should be placed onto a surveillance programme.

If you need an operation they will discuss the best surgical options and order tests to help the anaesthetist give you the safest anaesthetic.

Whilst we make every effort to ensure that the information contained on this site is accurate, it is not a substitute for medical advice or treatment, and the Circulation Foundation recommends consultation with your doctor or health care professional. 

The Circulation Foundation cannot accept liability for any loss or damage resulting from any inaccuracy in this information or third party information such as information on websites to which we link.

The information provided is intended to support patients, not provide personal medical advice