The aorta is your body's main artery, and an abdominal aortic aneurysm is a bulge in the section that runs through your belly

An abdominal aortic aneurysm (AAA) is a weakened, enlarged section of the aorta—the large artery that carries blood from your heart down through your chest and abdomen. The weakened wall balloons outward, like a tire bulging where the rubber has thinned. Most people with an AAA have no symptoms at all and discover it only during imaging for another reason. The danger is rupture: if the aneurysm tears open, blood spills into the abdomen rapidly, and without emergency surgery, rupture is usually fatal.

The aorta in your abdomen is narrower and more vulnerable than the section in your chest, which is why AAA is more common than thoracic aneurysm. An aneurysm is typically defined as a bulge that is 3 centimeters or larger in diameter—roughly the width of a large grape. Smaller bulges exist but are watched rather than treated immediately.

Key Takeaways

  • Most abdominal aortic aneurysms cause no symptoms, so many people do not know they have one until imaging for an unrelated reason finds it.
  • Risk rises sharply in men over 65, smokers, and people with high blood pressure or a family history of aneurysm.
  • Screening with ultrasound is recommended once for men aged 65 to 75 who have ever smoked, and for anyone with a parent or sibling who had an AAA.
  • Small aneurysms (under 5.5 centimeters) are usually monitored with regular ultrasound rather than operated on immediately.
  • Rupture is a medical emergency requiring immediate surgery; symptoms include sudden severe pain in the back, abdomen, or side, and shock.

Who is at higher risk for abdominal aortic aneurysm

Age and sex are the strongest risk factors. Men are five to ten times more likely to develop an AAA than women, and risk rises sharply after age 65. Smoking is the second major factor—current and former smokers have a much higher risk than people who have never smoked. High blood pressure, high cholesterol, and chronic obstructive pulmonary disease (COPD) also increase risk.

Family history matters significantly. If a parent or sibling had an AAA, your own risk is higher, and screening is recommended even at younger ages. Genetic conditions that weaken connective tissue—such as Marfan syndrome or Ehlers-Danlos syndrome—also raise risk. Inflammation of the aorta (a rare condition called aortitis) can lead to aneurysm formation as well.

Screening and how aneurysms are found

Most AAAs are found by accident during imaging ordered for another reason—a CT scan for kidney stones, an ultrasound for abdominal pain, or an X-ray of the spine. Intentional screening is recommended for specific groups. The U.S. Preventive Services Task Force recommends a one-time ultrasound screening for men aged 65 to 75 who have ever smoked. Men in that age range who have never smoked may also be screened if they choose. Women are not routinely screened unless they have a strong family history or other risk factors.

Ultrasound is the standard screening tool because it is non-invasive, inexpensive, and accurate. It takes about 10 to 15 minutes and requires no special preparation. If ultrasound finds an aneurysm, CT angiography (a more detailed imaging test) is usually done to measure it precisely and plan treatment. The measurement—the diameter of the bulge—determines whether the aneurysm is watched or treated.

Size matters: when an aneurysm is monitored versus treated

An aneurysm smaller than 5.5 centimeters in diameter is typically not operated on immediately. Instead, it is monitored with regular ultrasound or CT scans—usually every 6 to 12 months, depending on the size and how fast it is growing. Monitoring allows time to see whether the aneurysm is stable, shrinking, or enlarging. Many small aneurysms never rupture and remain stable for years.

An aneurysm 5.5 centimeters or larger, or one that is growing rapidly (more than 1 centimeter per year), is usually treated with surgery. The surgeon either replaces the weakened section with a synthetic graft or, in some cases, places a stent graft inside the artery to reinforce it. The choice depends on the aneurysm's shape, location, and the patient's overall health. Surgery carries its own risks, which is why smaller aneurysms are watched first—the risk of rupture at smaller sizes is lower than the risk of surgery itself.

What rupture feels like and why it is an emergency

A rupturing or ruptured abdominal aortic aneurysm causes sudden, severe pain—usually in the back, lower abdomen, or side. The pain is often described as tearing or ripping and is unlike anything the person has felt before. Some people also feel pain radiating into the groin or legs. Shock may follow quickly: dizziness, fainting, rapid heartbeat, and pale or clammy skin.

Rupture is a life-threatening emergency. Blood loss happens within minutes, and without immediate surgery, most people do not survive. If you or someone near you experiences sudden severe abdominal or back pain with signs of shock, call 911 immediately. Do not wait or try to drive to the hospital. Emergency surgery to repair the rupture is the only treatment, and survival depends on reaching the operating room as quickly as possible.

Living with a monitored aneurysm

If you have been told you have an AAA that is being monitored, your main tasks are to keep your scheduled imaging appointments and manage the conditions that increase rupture risk. High blood pressure is the most important to control—keeping blood pressure in a healthy range reduces stress on the aneurysm wall. Your doctor will likely prescribe blood pressure medication if you do not already take one.

Smoking accelerates aneurysm growth, so quitting is one of the most effective steps you can take. Avoiding heavy lifting and straining (which raises blood pressure suddenly) is also recommended. Some doctors prescribe beta-blockers or other medications that slow aortic growth, though the evidence for this is mixed. Regular follow-up imaging is essential—missing appointments means missing early signs that the aneurysm is growing and may need surgery soon.

The difference between abdominal and thoracic aortic aneurysm

The aorta runs from your heart through your chest and into your abdomen. An abdominal aortic aneurysm affects the lower portion, below the kidneys in most cases. A thoracic aortic aneurysm affects the section in the chest. Thoracic aneurysms are less common but often more dangerous because they can involve the aortic valve or the arteries that supply the heart and brain.

Thoracic aneurysms are more likely to cause symptoms—chest pain, back pain, or shortness of breath—because of their location near vital structures. Abdominal aneurysms are usually silent. Treatment decisions for thoracic aneurysms also differ; surgery is often recommended at smaller sizes because the risk of rupture in the chest is higher. If you have been told you have a thoracic aneurysm, the monitoring and treatment approach will be different from what is described here.

Frequently Asked Questions

Can an abdominal aortic aneurysm heal on its own?

No. Once the aorta wall is weakened and bulging, it does not repair itself. The aneurysm either stays stable, grows slowly, or grows quickly. Controlling blood pressure and quitting smoking can slow growth, but they cannot reverse the bulge. This is why monitoring with regular imaging is necessary—to catch growth before rupture becomes likely.

What does it mean if my aneurysm is growing?

Growth means the weakened section is expanding, which increases rupture risk over time. How fast it grows matters: slow growth (less than 0.5 centimeters per year) may not change your treatment plan, but rapid growth (more than 1 centimeter per year) usually means surgery should be scheduled soon. Your doctor will discuss the growth rate and what it means for your next steps.

Is surgery always successful?

Modern aneurysm surgery has good outcomes in most cases, but it carries real risks—infection, bleeding, kidney damage, and stroke are possible. The risk depends on your age, overall health, and whether the surgery is planned or emergency. Planned surgery for a stable aneurysm has better outcomes than emergency surgery for rupture. Your surgeon will discuss your individual risk before the procedure.

Can I exercise if I have an abdominal aortic aneurysm?

Moderate exercise is usually safe and can help control blood pressure. Heavy lifting, straining, and high-intensity exercise that causes sudden blood pressure spikes should be avoided. Ask your doctor what types of activity are safe for you based on your aneurysm size and how fast it is growing.

Should my family members be screened?

If you have an AAA, your siblings and parents have a higher risk than the general population and may benefit from screening. Talk to your doctor about whether screening is recommended for your relatives, especially men over 65 or anyone with other risk factors like smoking or high blood pressure.