| Clinical question | Does my patient have an abdominal aortic aneurysm (AAA); if so, is it ruptured or at risk of rupture? |
|---|---|
| Patient positioning | Supine (best for abdominal organ visualization) |
| Elevate head of bed if needed for comfort | |
| Bending knees may reduce abdominal wall tension and improve views | |
| Supplies needed | None |
| Probe | Curvilinear Probe on Abdominal or Aorta preset |
| Normal findings | Aortic diameter: <3.0 cm |
| Tapers gradually as it courses distally | |
| Echogenic walls, pulsatile in real time | |
| No intraluminal thrombus or flap | |
| Bifurcation into iliac arteries seen distally | |
| Sensitivity & specificity | Sensitivity: >95% for detecting AAA |
| Specificity: >98% | |
| Less sensitive in obese patients or with bowel gas (meta-analysis excluded patients in which the aorta could not be visualized) | |
| Cannot reliably detect rupture, but can suggest it via adjacent free fluid | |
| Contraindications | No absolute contraindications |
| Alternate diagnostic modalities | CT Angiography: Gold standard for evaluating size, rupture, and surgical planning |
| MRI Angiography: Alternative in patients with contrast allergy or renal dysfunction | |
| Plain X-ray: May show calcified aneurysm, but insensitive | |
| Physical exam: Low sensitivity, particularly in obese patients |
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An aneurysm of the abdominal aorta is defined as diameter >3 cm or iliac arteries >1.5cm
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