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EUS of the abdominal aorta is used to diagnose or exclude an abdominal aortic aneurysm (AAA). Although the sensitivity of abdominal ultrasound for the detection of aortic dissection is limited, the presence of an intra-aortic flap is diagnostic for aortic dissection.
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Abdominal, back, or flank pain
Pulsatile abdominal mass
Undifferentiated hypotension
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When a patient is unstable, there is no bedside test superior to an EUS of the abdominal aorta to diagnose an AAA. Early diagnosis can improve patient survival. An abdominal aortic measurement greater than 3 cm in diameter is abnormal and diagnostic of an AAA. While an AAA may rupture at any size, the risk of rupture is much greater starting with measurements greater than 5 cm. AAAs occur as both fusiform (more common) and saccular types. It is essential to image the aorta in both sagittal and transverse planes.
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Views for Emergency Department Abdominal Aortic Ultrasound
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Transverse view
Sagittal view
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Equipment: Recommended Transducer for Abdominal Aortic Ultrasound
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Place the transducer in the epigastrium with the transducer indicator oriented to the patient’s right (Fig. 24.56).
Identify the acoustic shadow caused by the vertebral body. The abdominal aorta is the circular, pulsating, anechoic structure anterior and slightly to the patient’s left.
Identify and measure the aorta at the proximal (at or above the origin of the superior mesenteric artery [SMA]), middle (near the renal arteries), and distal (immediately proximal to the bifurcation) in the anteroposterior plane (Figs. 24.57 and 24.58).
Identify the aorta in relation to the IVC, SMA, and splenic vein.
Move down the abdominal aorta to the bifurcation (approximately the level of the umbilicus) (Fig. 24.59).
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