Abdominal aneurysms: Uncommon but potentially dangerous

An aneurysm — an abnormal bulge or balloon-like pouch in an artery — can form in different places in the body and the brain. But most arise in the body's largest artery, the aorta, as it passes through the center of the body (see illustration). These abdominal aortic aneurysms (AAAs) occur in up to 7% of people ages 50 and older, most commonly in older male smokers.

Most of the time, these bulges stay small, grow slowly, and pose little risk. But a small number expand quickly and may rupture with little warning. The resulting massive bleeding inside the abdomen is usually fatal.

"Unfortunately, abdominal aneurysms don't cause any symptoms until they're about to rupture or are rupturing," says Dr. Marc Schermerhorn, chief of vascular surgery at Harvard-affiliated Beth Israel Deaconess Medical Center. Located deep inside the body just on top of the spine, this section of the aorta is about 2 centimeters (cm) wide. During routine physical exams, primary care providers usually can't feel small aneurysms in the abdominal aorta, and even a large aneurysm is easy to miss, says Dr. Schermerhorn. That's why people at greatest risk for an AAA should be screened with a one-time abdominal ultrasound — a simple, painless test that takes about 30 minutes.

Who should be screened?

The screening test for an AAA is fully covered by Medicare Part B for

• anyone with a family history of AAA
• men between ages 65 to 75 who have smoked at least 100 cigarettes at any point during their lives.

However, few people seem to be taking advantage of this free screening. If you qualify and your physician hasn't recommended the test, ask him or her to order the screening, says Dr. Schermerhorn.

Why aneurysms form

Cigarette smoking is a potent risk factor for many diseases, and AAAs are no exception. Even men who smoked only casually for a brief time when they were younger face a heightened risk, says Dr. Schermerhorn. "The effect triggered by smoking can happen during your 20s but not show up until years later," he says. The more you smoked, the higher your risk. Quitting after you're diagnosed definitely helps, since people who continue to smoke tend to fare much worse than those who stop, he adds. High blood pressure can also increase the odds that an aneurysm will grow and rupture.

Monitoring AAAs

If your screening test detects a small aneurysm (a diameter of less than about 4 cm), it should be rechecked every two years. If the aneurysm expands to 4 cm, annual checks are recommended, and every six months if it grows larger than 4.5 cm. Dr. Schermerhorn urges his patients not to worry too much about small aneurysms. "We want people to be just concerned enough to show up for their next surveillance test," he says. Most never reach a size that would require an intervention, but surveillance can detect the rare cases that warrant treatment.

The risk of a rupture rises as an aneurysm grows larger. If that happens, it usually causes a sudden, sharp pain in the back, or sometimes in the front of the belly. Occasionally, the pain radiates to one side (usually the left) or toward the groin. Many people with AAAs also have chronic low back pain, but the pain associated with a rupture feels new and different, says Dr. Schermerhorn.

Treating an AAA

If an AAA grows large enough, the risk of a rupture outweighs the risk of repairing it. For men, that's about 5.5 cm; for women, about 5 cm. However, the person's overall surgical risk and how quickly the aneurysm has grown are also important considerations. A CT scan of the abdomen provides a more detailed look of the aneurysm, which helps surgeons determine the best treatment option. Some AAAs are repaired with open surgery, but most are done with a minimally invasive technique: the physician threads a catheter through a vessel in the upper leg up to the aorta and places a fabric-coated metal cage to reinforce the bulging portion.

Illustration by Scott Leighton