What is abdominal aortic aneurysm (AAA)?

The aorta is the largest artery in your body and it carries blood away from your heart. Your aorta runs through your chest and into abdomen. The abdominal aorta supplies blood to the lower part of the body. Just below the abdomen, the aorta divides into two branches that carry blood into each leg. When a weak area of the abdominal aorta expands or bulges, it is called an abdominal aortic aneurysm (AAA). The pressure from blood flowing through your abdominal aorta can cause a weakened part of the aorta to bulge, much like a balloon. A normal aorta is about 1 inch (or about 2 centimetres) in diameter. However, an AAA can stretch the aorta beyond its safety margin.

When aneurysms become very large (bigger than 5.5cm or about 2 inches), they may burst, or rupture. Once an aneurysm reaches that size, then surgery is usually considered provided the risks of surgery are acceptable. However, smaller aneurysms rarely burst and, in many cases, never grow to a size where they are likely to give rise to problems. For this reason, if your aneurysm is small (less than 5.5cm) it is usually safest for you to have your aneurysm monitored by regular scans as you may completely avoid the need for a surgical procedure.

What is the cause of AAA?

Many factors contribute to AAA formation. It is more common among men older than 60, smokers, Caucasians and anyone with a first-generation relative (father, son, brother) are known to be at higher risk. Age (50+ for men, 60+ for women) and a history of atherosclerosis, high blood pressure, elevated cholesterol, heart or peripheral vascular disease and tobacco use are all associated with AAA formation. Other potential factors associated with AAA formation include tears in the arterial wall, infections, and congenital connective tissue disorders.

How will it be monitored?

It is not easy to determine the size of an aneurysm by examining the abdomen and a scan is required. Usually, an ultrasound scan will allow us visualise the aorta to determine the size. This is performed in the vascular laboratory. No anaesthetic or special preparation is required though you may be asked to fast before the test as this reduced the amount of gas in the bowel and makes it easier to visualise the aorta. The scan is painless and takes only a few minutes. During the scan, the technologist will press an ultrasound probe on the abdomen.This test is usually repeated at six monthly intervals but your doctor will discuss the precise timing of each scan with you after the test.

You will be told the result after your scan and an appointment will be made for your next scan; this will normally be posted out to you or confirmed by telephone closer to your appointment date. If you do not get your followup appointment, please contact the vascular laboratory.   

In some cases, a CT scan is required. This will be performed in the radiology department. During this scan, you may require an intravenous injection. A CT scan itself is painless and also only takes a few minutes.

What happens if the aneurysm grows larger?

If the aneurysm grows bigger than 5.5cm, surgery may be considered. An appointment will be arranged with your surgeon to discuss the need for surgery and to explain the procedure to you.  This may be performed using keyhole technology in some cases or using conventional open surgery. You will be told which is most appropriate in your case and the procedure will be explained to you. If you wish to read more about the surgical procedure, there are information pages available on both techniques. 

What should I watch out for?

In the vast majority of cases, smaller aneurysms cause no symptoms or problems. However, should you develop sudden severe abdominal or back pain, then you should attend immediately (to the Emergency department) to have your aneurysm checked.