An abdominal aortic aneurysm (AAA) is an inflammation (aneurysm) of the aorta - the main blood vessel leading from the heart, down through the abdomen to the rest of the body.
The abdominal aorta is the body's largest blood vessel and is usually about 2 cm wide - about the width of a garden hose. However, you can increase to more than 5.5 cm - what doctors class as a great AAA.
Large aneurysms are rare but can be very serious. If a large aneurysm ruptures a massive internal bleeding occurs and is usually fatal.
The swelling occurs when the aortic wall weakens. Although the causes of this weakness is clear, it is believed that smoking and high blood pressure which increases the risk of an aneurysm.
AAA is more common in men over 65 years accounts rupture of more than 1 in 50 of all deaths in this group and a total of 6,000 deaths in England and Wales each year.
That is why all men are invited to a screening test when they turn 65. The test consists of a simple ultrasound, which takes about 10-15 minutes.
Symptoms of an AAA
In most cases, a AAA not cause any noticeable symptoms. However, if it becomes large, some people may develop a pain or throbbing in the abdomen (belly) or persistent back pain.
AAA usually not a serious health threat, but there is a risk that a large aneurysm could burst (rupture).
A ruptured aneurysm can cause massive internal bleeding, which is usually fatal. About 8 out of 10 people with a rupture die before reaching the hospital or do not survive the surgery.
The most common symptom of a ruptured aortic aneurysm is a sudden, sharp pain in the abdomen.
Read more about the symptoms of a AAA.
The causes of AAA
It is not known exactly what causes the wall of the aorta weaken, although the increasing age and male sex are known to be the major risk factors.
There are other risk factors you can do something about it, including smoking and high blood pressure and cholesterol.
Having a family history of aortic aneurysms also means that you have a higher risk of developing oneself.
Read more about the causes of AAA.
The diagnosis of AAA
Because AAA usually cause no symptoms, they tend to be diagnosed either as a result of screening or during a routine examination - for example, if a doctor realizes throbbing in the abdomen.
The screening test is an ultrasound, which allows the size of the abdominal aorta to measure on a monitor. This is also how an aneurysm is diagnosed if your doctor suspects you have one.
More information about the diagnosis of AAA.
Treating an AAA
If a large AAA before break is detected, it will advise most people to receive treatment to prevent breakage.
This is usually done with surgery to replace the weakened section of blood vessel with a piece of plastic pipe.
If surgery is not recommended - or choose not to have it - there are a number of non-surgical treatments that can reduce the risk of a ruptured aneurysm.
These include drugs to lower cholesterol and blood pressure, and smoking cessation.
You will also have the size of your aneurysm checked regularly with ultrasound.
