Diseases & Conditions

Abdominal Aortic Aneurysm


Overview, Causes, & Risk Factors

Abdominal aortic aneurysm (AAA) is the term for enlargement and weakening of a portion of the abdominal aorta.

What is going on in the body?

The abdominal aorta is the main blood vessel that supplies blood to internal organs in the lower part of the body. Under certain conditions, a section of the aorta may weaken and swell. If the aneurysm should burst, large amounts of blood can be lost. This can quickly cause death. Blood can also leak in between the layers of the aorta and block arteries leading from it. This can cause serious damage to the organs supplied by those arteries.

What are the causes and risks of the condition?

The most common cause of AAA is atherosclerosis. In this condition, a fatty material builds up inside the aorta. This buildup causes inflammation and weakens the affected blood vessel.

Other causes of abdominal aortic aneurysms include:

  • injury, such as a crush injury from a motor vehicle accident
  • inherited conditions that cause weakened or abnormal blood vessel walls
  • infection carried in the bloodstream from other parts of the body
  • High blood pressure increases the risk of AAA. More than half of those diagnosed with AAA have high blood pressure. Cigarette smoking also increases the risk of AAA and can make AAA worse. Chronic coughing, such as the cough from chronic obstructive pulmonary diseases such as emphysema, can make the aneurysm worse.

    AAA is more common among Caucasian people. It affects men 4 times more often than women. It occurs most often in people between ages 60 and 90.


    Symptoms & Signs

    What are the signs and symptoms of the condition?

    Many people with an abdominal aortic aneurysm have no symptoms. But sometimes AAA is very painful. The pain is often felt in the lower back or the abdomen. It is usually a steady pain that does not go away, although it may be relieved by changing position. Sometimes the person can sense an abnormal pulse in the abdomen. Circulation to the lower extremities can be affected.

    Rupture of an abdominal aortic aneurysm is usually associated with sudden, excruciating pain in the lower abdomen and back. Depending on the severity of the internal bleeding, the person may go into shock, and death may rapidly follow.


    Diagnosis & Tests

    How is the condition diagnosed?

    A physical examination will often reveal an enlarged abdominal aorta. The healthcare provider can sometimes hear abnormal sounds over the enlarged aorta. An ultrasound test is commonly used to confirm the diagnosis of AAA. Other imaging studies, such as an abdominal CT scan or abdominal MRI, may be done to provide more information about the aneurysm.


    Prevention & Expectations

    What can be done to prevent the condition?

    People can lower their risk of abdominal aortic aneurysm by:

  • controlling high blood pressure
  • avoiding or treating high cholesterol
  • quitting smoking
  • obtaining effective treatment for chronic obstructive pulmonary disease
  • What are the long-term effects of the condition?

    A ruptured abdominal aortic aneurysm can cause death. Small aneurysms that have not ruptured are monitored closely to prevent rupture.

    What are the risks to others?

    Abdominal aortic aneurysms are not contagious and pose no risk to others.


    Treatment & Monitoring

    What are the treatments for the condition?

    Only 40% to 50% of the people with a ruptured abdominal aortic aneurysm survive long enough to have surgery, which is the only treatment for the condition. Of those individuals, only half survive and recover from the surgery. Early detection of the aneurysm, before it ruptures, is key to successful treatment of the problem.

    If the aneurysm has not ruptured, surgery is recommended in the following situations:

  • when the person has severe symptoms
  • when the aneurysm is bigger than 5 cm across
  • when it has grown by at least 1 cm over 6 to 12 months
  • In surgery, the weakened part of the aorta is removed. An artificial graft is then used to replace the portion removed.

    What are the side effects of the treatments?

    If surgery has been performed before rupture, and the patient is relatively healthy, the outcome is very good. But emergency surgery for a ruptured AAA has about a 50% chance of death. Other side effects include bleeding, infection, and allergic reaction to the anesthesia.

    What happens after treatment for the condition?

    After recovery from surgery, the person can slowly return to regular activities. It's important to make appropriate lifestyle changes to lower the risk of further circulatory system problems. These changes include eating a healthy diet to minimize heart disease, avoiding smoking, exercising in moderation, and maintaining a healthy weight.

    How is the condition monitored?

    Before surgery, the size of an aneurysm can be evaluated using an ultrasound test. After recovery from surgery, the person should have no further symptoms. Any new or worsening symptoms should be reported to the healthcare provider.


    Attribution

    Author:Eric Berlin, MD
    Date Written:
    Editor:Ballenberg, Sally, BS
    Edit Date:01/31/01
    Reviewer:Barbara Mallari, RN, BSN, PHN
    Date Reviewed:07/13/01

    Sources

    Merck Manual, 1999, Beers et al.

    Harrison's Principles of Internal Medicine, 1997, Fauci et al.

    Medical Knowledge Self Assessment Program, Cardiovascular Medicine Section, 1998, American College of Physicians.