Aneurysm of the abdominal aorta is a relatively common disease in patients over 50 years of age.1–3 Rupture of an abdominal aortic aneurysm (AAA) has a high mortality and causes as many as 30,000 deaths per year in the United States, which is more than AIDS or prostate cancer.4 It is one of the least-known killers in American society.4
More than 100 years ago, William Osler said, “There is no disease more conducive to clinical humility than aneurysm of the aorta.” This remains true today, as the diagnosis of ruptured AAA continues to confound clinicians. Misdiagnosis of ruptured AAA is common because many patients have not had a previously asymptomatic AAA formally diagnosed; they also may present with nonspecific complaints and have normal vital signs.5–7 Mortality due to AAA is decreased if the diagnosis is made prior to rupture or if the diagnosis is made rapidly after rupture of AAA.8–13
The availability of bedside ultrasound in the emergency department (ED) has allowed emergency physicians to change their approach to patients at risk for a ruptured AAA. A screening bedside ultrasound examination can now be obtained on patients over 50 years of age who present with pain in the abdomen, back, flank, or groin, and on those who present with dizziness, syncope, unexplained hypotension, or cardiac arrest.2, 14 This practice is analogous to the imme-diate acquisition of an electrocardiogram for all patients with possible myocardial infarction. In this capacity, ultrasound clearly can save lives, making this application one of the indisputable benefits of emergency bedside ultrasound.8, 9, 13, 15
Abdominal aortic aneurysm occurs in 2–5% of the population over 50 years of age and about 10% of men over 65 years of age who have risk factors for vascular disease.16–22 The prevalence is even higher in patients with first-degree relatives who have an AAA and those with peripheral vascular disease.4, 23 AAA is about four times more prevalent in men than in women.24–26 The prevalence has been steadily rising in both men and women over the past several decades, so despite advances in diagnostic imaging and surgical techniques there has been essentially no change in the number of patients presenting with ruptured AAA.27–31
The risk of AAA rupture is directly related to the largest diameter of the aneurysm and increases dramatically in those greater than 5 cm. Estimates of rupture risk are as follows: less than 2% per year for aneurysms smaller than 4 cm, 1–5% per year for those 4–5 cm, 3–15% per year for those 5–6 cm, 10–20% per year for those 6–7 cm, and 20–50% per year for those larger than 7 cm.32–37 Other factors such as continued smoking, uncontrolled hypertension, and emphysema increase the risk of rupture.38, 39 Also, women have a higher risk for rupture than men with the same-size aneurysm.32...