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What is an Abdominal Aortic Aneurysm?

An abdominal aortic aneurysm (AAA) is a swelling of the aorta – the main blood vessel that leads away from the heart to deliver oxygen-rich blood to the rest of the body.

The aorta is the largest artery in the body. Measuring around two centimetres in diameter, the aorta descends from the heart through the chest and abdomen before dividing into two arteries around the pelvis to deliver blood to each leg.

An aneurysm occurs when a section of the aorta weakens and balloons from the pressure of the blood. Although aneurysms can occur in any artery, they most commonly occur in the aorta, particularly in the section that passes through the abdomen. These are known as abdominal aortic aneurysms.

AAAs vary in size but some can swell to more than five centimetres wide. Large AAAs are rare but they can be very serious or even fatal if they burst as they can cause massive internal bleeding.


In most cases, an AAA that hasn’t ruptured will cause no noticeable symptoms. Larger AAAs may cause some people to feel persistent back or abdominal pain as well as a pulsating feeling in their abdomen, commonly around the belly button.

An AAA will not usually pose a serious threat to health, but a ruptured aneurysm will commonly cause sudden and severe abdominal pain as well as dizziness, breathlessness, a rapid heartbeat and unconsciousness. A ruptured AAA is usually fatal.

A ruptured aneurysm is classed as a medical emergency so it is crucial an ambulance is called for anyone who suffers one. Unfortunately, around 80 per cent of people who suffer a ruptured AAA will die before they reach hospital. Ruptured aneurysms account for around 6,000 deaths every year in England and Wales.


It is not known exactly what causes the aortic wall to weaken but both age and gender can play a part as well as a family history of aortic aneurysms. Lifestyle factors such as smoking and having high cholesterol or blood pressure are also believed to increase the risks of developing an aneurysm.


Men aged over 65 are much more likely to suffer an AAA than younger men or women. As AAAs usually cause no symptoms, they tend to only be diagnosed during routine physical examinations or if a distinctive pulsating sensation is noticed in the abdomen.

Diagnosis can be confirmed with an ultrasound. The NHS AAA screening programme automatically invites men for an ultrasound screening test in their 65th year.

Screening to allow the size of a patent’s abdominal aorta to be measured is a way of detecting an aneurysm early. If a patient’s abdominal aorta is normal, they will never usually need to be screened again. This is because most aneurysms grow so slowly it is unlikely one will develop after the age of 65. If a large AAA is detected, however, a patient should be referred to hospital within two weeks for treatment.


If a large AAA is detected, treatment is strongly advised to prevent it from rupturing. Treatment can involve open abdominal surgery to replace the damaged section of aorta with a synthetic tube. Major surgery of this kind is not normally recommended for patients in poor health and recovery time can take up to a month or more.

Another much safer and less invasive option is to have endovascular surgery. This involves inserting a synthetic graft attached to a catheter through an artery in the leg and threading it up to the aorta. The graft is placed at the aneurysm site and fastened in place to reinforce the damaged section of aorta and prevent it from rupturing. Recovery time is much shorter for this type of operation and there are fewer complications such as infections or deep-vein thrombosis.

Expert Opinion

We have dealt with a number of claims where clients have had their abdominal aortic aneurysm misdiagnosed. Often the condition is only discovered during investigations for other conditions but most of the claims we have dealt with have involved clients whose AAA was missed in A&E departments or medical assessment units.

Unfortunately clinical negligence errors in diagnosis are not uncommon and criticisms are usually for failing to correctly diagnose patients and get them to surgery in time to maximise their chances of survival. Mistakes such as failing to spot AAA or confusing the symptoms with something else can be catastrophic as patients who are not properly treated may die within hours.

If you or a member of your family suffered from negligent treatment in hospital, for a free consultation contact us here and we'll be happy to help you.

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