An aortic aneurysm is a local enlargement or bulge in the aorta, the body's largest artery. The aorta originates at the left ventricle of the heart, travels through the chest and abdomen, and supplies blood to every tissue and organ.

An aortic aneurysm is defined as an enlargement that is at least 50 percent greater than the normal size of the aorta. Although an aneurysm can occur in the thoracic (chest) portion of the aorta, an abdominal aortic aneurysm (AAA) is far more common.

Quite unusual before age 60, AAAs increase in prevalence dramatically with age, so that an AAA is present in 4 percent to 9 percent of people over the age of 60. More than 200,000 abdominal aortic aneurysms (AAAs) are diagnosed in the United States each year. The vast majority of these AAAs are too small to be clinically important, and they generally cause no symptoms.

Rupture of an AAA, however, is a catastrophic medical emergency because more than two thirds of people with AAAs never reach a hospital in time, and less than half of those who do get to a hospital survive. AAAs are the 17th leading cause of death in the U.S., accounting for more than 15,000 deaths annually.

Clearly, preventing rupture of an AAA is the only reasonable strategy. So what can you do to avoid having a ruptured AAA? A few people may go to their doctor complaining of pain in the abdomen, back, or groin that turns out to be caused by an expanding aortic aneurysm. The doctor may then detect an AAA by feeling a pulsating mass in the abdomen.

Other AAAs are detected during routine physical examinations or by an imaging procedure done for some other reason. Most AAAs, however, are discovered by ultrasound screening done for the expressed purpose of looking for one.

Like heart attacks, strokes, and peripheral artery disease, AAAs are caused by atherosclerosis and are subject to some of the same risk factors as coronary heart disease (CHD) — smoking, high blood pressure, and elevated cholesterol levels. In addition, AAAs are more common in those whose family members have had an AAA.

Who should undergo screening for an AAA? 

• A U.S. Preventive Task Force has recommended that all men between the ages of 65 and 75 who have ever smoked get a one-time ultrasound screening.
• Conversely, the Task Force does not recommend screening for women because they are at much lower risk for an AAA than are men.
• The Task Force also does not recommend that men older than 75 be screened, since this population is assumed to have too limited a life expectancy and to be at too great a risk from surgery, to benefit from repair of an AAA.
• The Task Force made no recommendation for or against screening for AAA in men of any age who have not smoked. 

These are of course recommendations and not rules; you and your doctor might choose screening even if you are a women or man who has never smoked.

I suggest that both men and women discuss ultrasonic screening with their doctor if they are age 65 or older and are known to have CHD, poor blood supply to their legs, or a family history of AAA. Nonsmoking men might consider screening at age 65 if they are strongly positive for the other CHD risk factors. Even people older than 75 might wish to be screened if they are in great health and willing to undergo surgery if it's needed.

Aortic ultrasound is completely safe and relatively inexpensive. If a screening test after age 65 is negative, it need never be repeated. Of course, there are negative features to screening. Detection of an AAA will likely produce anxiety as well as additional costs for follow-up ultrasound tests.

If an AAA is found, repeat ultrasound evaluations are obtained every 6 months to determine whether the AAA is expanding, since aneurysm size is the greatest predictor of rupture. Two different types of surgery are possible for dangerously large AAAs and both have proven to significantly reduce rupture and death from an AAA.