19 - Ultrasonography of the Abdominal Aorta

Summary

INDICATIONS

The primary indication for emergent ultrasonography of the aorta is to identify an abdominal aortic aneurysm (AAA). AAAs develop slowly and may be asymptomatic or present with life-threatening rupture. AAA rupture accounts for more than 10,000 deaths per year in the United States (1). Initial misdiagnosis is common because AAAs may present in a myriad of ways. In the words of Sir William Osler, “There is no disease more conducive to clinical humility than aneurysm of the aorta” (2). Ruptured AAAs can present with abdominal pain, flank pain, syncope, lower extremity paresthesias, or peripheral emboli (3),(4). Because physical examination is only moderately sensitive in the detection of AAAs, further evaluation with imaging is usually indicated (5).

DIAGNOSTIC CAPABILITIES

When ruptured or leaking AAA is suspected, ultrasound has many appealing qualities. Particularly for the hemodynamically unstable patient, bedside ultrasonography offers a prompt, accurate diagnosis. In even modestly experienced hands, ultrasound of the aorta can be performed rapidly and can detect the presence of an aneurysm in 95% to 98% of cases (6–8). In addition, it can be performed bedside, setting it apart from other modalities such as CT, MRI, and angiography, whereby the patient has to leave the department. Last, it has the added advantage of not requiring radiation or exposure to contrast material.