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.
This is why all men are invited for a ultrasound scan, which takes around 10-15 minutes.
Symptoms of an AAA
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.
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.
If you suspect that you or someone in your care has had a ruptured aneurysm, call 999 immediately and ask for an ambulance.
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.
An abdominal aortic aneurysm (AAA) occurs when part of the aorta wall becomes weakened and the large amount of blood that passes through it puts pressure on the weak spot, causing it to bulge outwards to form an aneurysm.
The abdominal aorta is usually around 2cm wide – about the width of a garden hosepipe – but can swell to over 5.5cm, which is what doctors classify as a large aneurysm.
Risk factors for 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.
One study found that people aged over 75 are seven times more likely to be diagnosed with an AAA than people under 55 years old.
Men are around six times more likely to be diagnosed with an AAA than women.
However, there are other risk factors that you can do something about – described below – the most important of which is smoking.
Research has found that smokers are seven times more likely to develop an AAA than people who have never smoked.
The more you smoke, the greater your risk of developing an AAA. 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 tobacco smoke contains harmful substances that can damage and weaken the wall of the aorta.
Atherosclerosis is a potentially serious condition where arteries become clogged up by fatty deposits, such as cholesterol.
An AAA is thought to develop because these deposits (called plaques) cause the aorta to widen in an attempt to keep blood flowing through it. As it widens, it also gets weaker.
Smoking, eating a high-fat diet and high blood pressure all increase your risk of developing atherosclerosis.
An abdominal aortic aneurysm (AAA) usually causes no symptoms. Therefore, they tend to be diagnosed as a result of screening, or during a routine physical examination when a GP notices a distinctive pulsating sensation in your abdomen.
A diagnosis can be confirmed using an ultrasound scan. Ultrasound can also determine the size of the aneurysm, which is an important factor in deciding on a course of treatment.
All men in the UK who are 65 or over are offered an ultrasound scan to check for AAAs.
All men should receive an invitation in the year they turn 65 years old. Men who are older than 65 can refer themselves for screening by contacting their local NHS AAA screening service.
Treatment for an abdominal aortic aneurysm (AAA) depends on several factors, including the aneurysm's size, your age and general health.
In general, if you have a large aneurysm (5.5cm or larger) you will be advised to have surgery, either to strengthen the swollen section of the aorta or to replace it with a piece of synthetic tubing.
This is because the risk of the aneurysm rupturing is usually greater than the risk of having it repaired.
If you have a small (3.0-4.4cm) or medium (4.5-5.4cm) aneurysm, you will be offered regular scans to check its size.
You will also be given advice on how to slow its growth and reduce the risk of it rupturing – for example, stopping smoking – and perhaps medications to reduce your blood pressure and cholesterol level.
If you have a large AAA
If you are diagnosed with an AAA that is 5.5cm or larger, you will be referred to a vascular surgeon (a surgeon who specialises in diseases of the blood vessels), who may recommend an operation.
The surgeon will discuss treatment options with you, taking into account your general health and fitness, as well as the size of your aneurysm.
If it's decided that surgery isn’t suitable for you, it’s still possible to reduce the risk of the aneurysm bursting, and you will have regular scans to check its size – in the same way people with small or medium aneurysms are treated.
See below for more information on treating small and medium aneurysms.
There are two surgical techniques used to treat a large aneurysm:
Although both techniques are equally effective at reducing the risk of the aneurysm bursting, each has its own advantages and disadvantages.
The surgeon will discuss with you which is most suitable.
Endovascular surgery is a type of "keyhole" surgery where the surgeon makes small cuts in your groin.
A small piece of tubing called a graft– made of metal mesh lined with fabric – is then guided up through the leg artery, into the swollen section of aorta, and sealed to the wall of the aorta at both ends.
This reinforces the aorta, reducing the risk of it bursting.
This is the safest of the two types of surgery available. Around 98-99% of patients make a full recovery, and recovery time from the operation is shorter than if you have open surgery.
There are also fewer major complications, such as wound infection or deep vein thrombosis (DVT).
However, the way the graft is attached is not as secure as open surgery. You’ll need regular scans to make sure the graft hasn’t slipped, and in some patients, the seal at each end of the graft starts to leak and will need to be resealed. You will need to have surgery again if either of these occurs.
In open surgery, the surgeon cuts into your stomach (abdomen) to reach the abdominal aorta and replaces the enlarged section with a graft.
This type of graft is a tube made of a synthetic material.
Because the graft is stitched (sutured) into place by the surgeon, it’s more likely to stay in place, and will usually work well for the rest of your life.
The risk of complications linked to the graft after surgery is lower than in people who have endovascular surgery.
Open surgery isn’t usually recommended for people who are in poor health as it is a major operation. It is slightly more risky than endovascular surgery, with 93-97% of patients making a full recovery.
The main risk of open surgery is death or heart attack, and recovery time is longer than with endovascular surgery.
There is also a greater risk of complications, such as wound infection, chest infection and DVT.
'I was able to go back to my part-time job within just three weeks'
When trumpeter Peter Cripps had a CT scan for a kidney stone, it was discovered he also had an abdominal aortic aneurysm (AAA).
“Just before Christmas, I had the most horrendous pain in my abdomen. I had a CT scan, which revealed I had a kidney stone. Thankfully, that was quite small but, more worryingly, the nurse told me I also had an AAA. The surgeon came to see me straight away and recommended an open AAA operation, which was done on January 16 2007.
“I’d had a four-way heart bypass four years earlier, and five years before that a heart attack, and I was convinced I was not going to make it. But the operation went really well, and I was out of hospital a week later.
“I felt weak and tired, and I was quite insecure when I first got home. I tried to do a little more each day and was soon back on my feet. In fact, I was able to go back to my part-time job fitting insulation mats on yacht engines within just three weeks. I play trumpet in a band and was able to start blowing again four weeks after the operation.
"I have to admit, there have been a few problems since the operation. The surgeon warned me that because the abdominal aorta runs down in front of the spine, it might interfere with my nervous system and that this could interfere with some of the "important bits".
"It’s true, things are not as brilliant in that department as they used to be, but there are always ways and means. Your digestion packs up too and I’m still not eating how I used to. I've lost a bit of weight and I’ve had a few problems with my bowels – mainly constipation – but I was told to expect that and I take laxatives.
"The scar is healing nicely, but it does still twinge a bit from time to time. Having said that, I’m feeling better by the day, and I’m just grateful it was found when it was, otherwise I might not be here.”