Abdominal Aortic Aneurysm

Basic Facts

An aneurysm is an enlarged portion of a weak area of an artery. Over time, blood flow can cause the weak area to bulge like a balloon. An abdominal aortic aneurysm (AAA) occurs in the abdominal section of the aorta, the main blood vessel that carries blood away from the heart.
Aneurysms can burst or rupture, causing serious internal bleeding and, if not treated, death. More than 15,000 people die of AAA ruptures in the United States each year. Aneurysms can also unleash potentially life-threatening blood clots.
The risk for complications increases with the size of the aneurysm. In general, abdominal aortic aneurysms that are slightly larger than 2 inches (about 5.5 cm) in diameter should be considered for treatment. Smaller aneurysms should be monitored carefully for any enlargement.

An abdominal aortic aneurysm (AAA) is an enlargement of a weak area of the main blood vessel (aorta) that carries blood away from the heart. A normal aorta is approximately one inch or less in diameter, while an aneurysm can grow to be more than five inches in diameter. The pressure of blood flowing through the artery can cause the weakened area to enlarge like a balloon. Larger aneurysms are more likely to burst than smaller ones, resulting in internal bleeding that is fatal unless treated immediately by an experienced emergency medical team. Because aneurysms can burst or rupture, they are considered a serious health condition. Only about half of patients with a ruptured AAA who get to a hospital survive.


Most people with AAA do not feel any symptoms; others may experience one or more of the following:

  • A rhythmic, pulsating feeling in the abdomen, similar to a heartbeat;
  • Deep pain in the abdomen or lower back; or
  • Severe, sudden abdominal or back pain that may indicate imminent rupture.
A normal aorta is 1 inch or less in diameter, but an aneurysm can grow to be 5 or more inches in diameter.

A ruptured aneurysm is life threatening and requires immediate medical attention.


The cause of AAA is unclear. Some researchers believe that it may be associated with atherosclerosis (hardening of the arteries); others believe that the same risk factors that contribute to atherosclerosis, such as high blood pressure and smoking, may make the aorta more vulnerable to aneurysms.

High-risk populations include:

  • Men older than 60 years;
  • Relatives of patients with aneurysms;
  • People with high blood pressure;
  • People with chronic obstructive pulmonary disease (COPD); or
  • People with vascular diseases.

Aneurysms may also be genetic, or in rare cases, can be caused by trauma, connective tissue disease (for example, Marfan’s syndrome), or bacterial or fungal infections.


Physicians can only detect about 10 percent of abdominal aortic aneurysms during a physical examination. Most abdominal aortic aneurysms are diagnosed during an abdominal imaging test; in fact, most aneurysms are discovered when an imaging test is conducted for an unrelated reason. The tests used to detect an aortic aneurysm may include:

  • Abdominal Ultrasonography (ultrasound) – The most common test used to diagnose aneurysms. This test takes approximately 30 minutes, is widely available, and can detect most aneurysms;
  • Computed Tomography (CT) scans; or
  • Magnetic Resonance Imaging (MRI).


Aneurysms that are smaller than two inches in diameter and do not cause symptoms may be monitored regularly (approximately every six months) using an ultrasound or CT scan, a practice called “watchful waiting.” People with small aneurysms and high blood pressure may be given medication to lower their blood pressure, which may reduce the risk of the aneurysm growing or rupturing.

Open Aneurysm Repair. Surgical repair may be recommended for patients whose aneurysms cause symptoms or are larger than two inches. The operation involves opening the abdomen and replacing the weakened area of the aorta with a fabric tube. This procedure may require a hospital stay of five to 10 days, and may take two to three months for recovery.

Endovascular Stent Graft Repair. A minimally invasive procedure, endovascular stent graft repair allows a physician to implant a synthetic tube (stent graft or endograft) supported by metal into the aorta. The tube is threaded into the aorta using a catheter inserted through a small incision in the groin. The stent graft allows blood to flow through the aorta without putting pressure on the damaged wall of the aneurysm. Following an endovascular stent graft, the aneurysm may eventually shrink over time.