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Overview of abdominal aortic aneurysm

Ronald L Dalman, MD
Matthew Mell, MD, FACS
Section Editors
John F Eidt, MD
Joseph L Mills, Sr, MD
Deputy Editor
Kathryn A Collins, MD, PhD, FACS


Mortality remains high for patients who experience rupture of an abdominal aortic aneurysm (AAA), but it has dropped considerably in the past 20 years due to a variety of factors [1]. Elective AAA repair prior to the development of symptoms is the most effective means to prevent rupture and aneurysm-related sudden death.

The definition of abdominal aortic aneurysm and aortic anatomy will be reviewed here together with an overview of the epidemiology, risk factors, pathogenesis, natural history, screening, clinical features and diagnosis, management, and surgical repair, with links to more detailed topics. Other types of arterial aneurysms are discussed separately.


Abdominal aortic aneurysm (AAA) is the most common true arterial aneurysm. A true aneurysm is defined as a segmental, full-thickness dilation of a blood vessel that is 50 percent greater than the normal aortic diameter (figure 1) [2]. False aneurysms of the abdominal aorta can also occur but are much less common and are usually due to a traumatic or infectious etiology.

In most adults, an aortic diameter >3.0 cm is generally considered aneurysmal. Normal aortic diameter varies with age, gender, and body habitus, but the average diameter of the adult human infrarenal aorta is approximately 2.0 cm; 95 percent of the adult population has an aortic diameter ≤3.0 cm [2]. Thus, for the majority of patients, an infrarenal aorta with a maximum diameter ≥3.0 cm is considered aneurysmal [2-4]. For men, diameter alone defines the presence of an AAA and predicts clinical events. However, for women, although the aorta is still considered aneurysmal when its diameter exceeds 3.0 cm, the diameter is less predictive of clinical events. An aortic scaling index (ASI), calculated as diameter (cm)/body surface area (m2), is more predictive of clinical events than absolute aortic diameter in women [5].

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Literature review current through: Nov 2017. | This topic last updated: Jul 24, 2017.
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