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An abdominal aortic aneurysm (AAA) is a swelling (aneurysm) of the aorta – the main blood vessel that leads away from the heart, down through the abdomen to the rest of the body.
The abdominal aorta is the largest blood vessel in the body and is usually around 2cm wide – roughly the width of a garden hose. However, it can swell to over 5.5cm – what doctors class as a large AAA.
Large aneurysms are rare, but can be very serious. If a large aneurysm bursts, it causes huge internal bleeding and is usually fatal.
The bulging occurs when the wall of the aorta weakens. Although what causes this weakness is unclear, smoking and high blood pressure are thought to increase the risk of an aneurysm.
AAAs are most common in men aged over 65. A rupture accounts for more than 1 in 50 of all deaths in this group and a total of 6,000 deaths in England and Wales each year.
In most cases, an AAA causes no noticeable symptoms. However, if it becomes large, some people may develop a pain or a pulsating feeling in their abdomen (tummy) or persistent back pain.
An AAA doesn’t usually pose a serious threat to health, but there’s a risk that a larger aneurysm could burst (rupture).
A ruptured aneurysm can cause massive internal bleeding, which is usually fatal. Around 8 out of 10 people with a rupture either die before they reach hospital or don’t survive surgery.
The most common symptom of a ruptured aortic aneurysm is sudden and severe pain in the abdomen.
If you suspect that you or someone else has had a ruptured aneurysm, call 999 immediately and ask for an ambulance.
Read more about the symptoms of an AAA.
It's not known exactly what causes the aortic wall to weaken, although increasing age and being male are known to be the biggest risk factors.
There are other risk factors you can do something about, including smoking and having high blood pressure and cholesterol level.
Having a family history of aortic aneurysms also means that you have an increased risk of developing one yourself.
Read more about the causes of an AAA.
Because AAAs usually cause no symptoms, they tend to be diagnosed either as a result of screening or during a routine examination – for example, if a GP notices a pulsating sensation in your abdomen.
The screening test is an ultrasound scan, which allows the size of your abdominal aorta to be measured on a monitor. This is also how an aneurysm will be diagnosed if your doctor suspects you have one.
Read more about diagnosing an AAA.
If a large AAA is detected before it ruptures, most people will be advised to have treatment, to prevent it rupturing.
This is usually done with surgery to replace the weakened section of the blood vessel with a piece of synthetic tubing.
If surgery is not advisable – or if you decide not to have it – there are a number of non-surgical treatments that can reduce the risk of an aneurysm rupturing.
You will also have the size of your aneurysm checked regularly with ultrasound scanning.
Read more about treating AAAs.
The best way to prevent getting an aneurysm – or reduce the risk of an aneurysm growing bigger and possibly rupturing – is to avoid anything that could damage your blood vessels, such as:
Read more about preventing aneurysms.
Men who are 65 and over are offered a screening test to check if they have an AAA.
All men in England are invited for screening in the year they turn 65.
Men who are over 65 and have not previously been screened can request a screening test by contacting their local AAA screening service directly.
Women and men under 65 are not invited for screening.
However, if you feel you have an increased risk of having an AAA, talk to your GP who can still refer you for a scan.
Read more about screening for an AAA.