Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (also known as AAA, pronounced "triple-a") is a localized dilatation (ballooning) of the abdominal aorta exceeding the normal diameter by more than 50 percent, and is the most common form of aortic aneurysm. Approximately 90 percent of abdominal aortic aneurysms occur infrarenally (below the kidneys), but they can also occur pararenally (at the level of the kidneys) or suprarenally (above the kidneys). Such aneurysms can extend to include one or both of the iliac arteries in the pelvis.

Abdominal aortic aneurysms occur most commonly in individuals between 65 and 75 years old and are more common among men and smokers. They tend to cause no symptoms, although occasionally they cause pain in the abdomen and back (due to pressure on surrounding tissues) or in the legs (due to disturbed blood flow). The major complication of abdominal aortic aneurysms is rupture, which is life-threatening, as large amounts of blood spill into the abdominal cavity, and can lead to death within minutes. Mortality in the hospital is 60% to 90%.

Surgery is recommended when the aneurysm is large enough (>5.5 cm in diameter) that the risk of surgery (1% to 6%) is less than the risk of rupture. In open surgery, the surgeon opens the abdomen and stitches in a replacement section of artery; in endovascular surgery the surgeon feeds the replacement section through the patient's artery and replaces it from inside.

There is moderate evidence to support screening in individuals with risk factors for abdominal aortic aneurysms (e.g., males ≥65).

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