Causes of an abdominal aortic aneurysm

The aorta is the largest blood vessel in the body. It transports oxygen-rich blood away from the heart to the rest of the body.

The aorta is a hollow tube, about the width of a hosepipe. The wall of the aorta is made up of elastic fibres.

An aortic aneurysm occurs when part of the aortic wall becomes weakened.

The large amount of blood that passes through the aorta puts pressure on the weak spot in the wall, causing it to bulge outwards to form an aneurysm.

Risk factors for an aortic aneurysm

It’s not known exactly what causes the aortic wall to weaken. However, several factors, many of which are related, have been linked to an increased risk of developing an abdominal aortic aneurysm. These are described below.


Probably the most important risk factor for aortic aneurysm is smoking. Research has found that smokers are seven times more likely to develop an aortic aneurysm than people who have never smoked.

The amount that you smoke increases the risk. People who regularly smoke more than 20 cigarettes a day may have more than 10 times the risk of non-smokers.

The risk may increase because smoking can cause hardening and narrowing of the arteries (atherosclerosis), and there may be harmful substances in tobacco smoke that could damage the walls of the aorta.


Atherosclerosis is a potentially serious condition where arteries become clogged up by fatty substances, such as cholesterol. This leads to the arteries becoming narrowed and hardened.

Smoking, eating a high-fat diet and high blood pressure all increase your risk of developing atherosclerosis.

High blood pressure

As well as contributing to atherosclerosis, high blood pressure can place increased pressure on the wall of the aorta.

Age and sex

The older you are, the more likely you are to develop an abdominal aortic aneurysm.

One study found that people aged over 75 are seven times more likely to be diagnosed with an aortic aneurysm than people under 55 years old.

Aortic aneurysms are also more common in men than women. Men are five times more likely to be diagnosed with an abdominal aortic aneurysm than women.

Family history

Having a family history of aortic aneurysms means that you have an increased risk of developing one.
One study found that people who had a brother or sister with an aortic aneurysm were eight times more likely to develop one than people whose siblings were unaffected.

This suggests that certain genes you inherit from your parents may make you more vulnerable to developing an aortic aneurysm. However, no specific genes have been identified yet.

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