Sweep down past the umbilicus until the single aorta becomes two, narrower vessels. This is where the aorta bifurcates into the right and left iliac arteries. Occasionally you may encounter an aneurysm in the iliac artery.
Aortic Iliac BifurcationAorta Bifurcation Ultrasound Probe Position
Visualize the common iliac arteries.
The Aorta Bifurcates into the Iliac ArteriesColor Doppler view of the Iliac Bifurcation
To see the Mid Aorta, slide your probe inferiorly, distally from the SMA, keeping the aorta in view at all times.
Mid AortaMid Aorta Ultrasound Probe Position
Visualize and measure the Mid Abdominal Aorta
The mid abdominal aorta lacks distinct anatomical landmarks. Occasionally, you will be able to visualize the renal arteries as an inferior boundary for this portion of the exam.
Measure the mid-aortic diameter once you have obtained a clear view.
The right and left renal arteries branching off the aorta
For the short axis abdominal aorta ultrasound protocol, you will examine the short axis of the abdominal aorta from the celiac trunk down to the iliac bifurcation in 3 main sections: proximal, mid, and distal. You will also measure the aortic diameter in each section.
Step 1: Proximal Abdominal Aorta
In the proximal abdominal aorta, you will distinguish the aorta from the IVC, view the celiac trunk/superior mesenteric artery, and measure the aortic diameter.
Place your probe just below the xiphoid process, slightly left of midline to the patient , with the probe indicator facing the patient’s right/examiner’s left (“9 o’clock”) to obtain a short axis/transverse view of the proximal aorta.
Proximal AortaProximal Aorta Ultrasound Probe Position
Adjust the depth until the hyperechoic vertebral body and its dense shadow are visible at the bottom of the screen.
Identify the Aorta, a thick-walled, hypoechoic, pulsatile circle just above the vertebral body, slightly right of midline (patient’s left) on the screen.
Identify the IVC. It won’t be as circular as the aorta, will lie left of midline on the screen (patient’s right), and is usually collapsible with respirations.
Keep the probe perpendicular to the abdominal wall for the best short axis view, and accurate subsequent measurements.
Short axis view of the proximal aorta.
Tip: If you cannot see these structures, gas in the transverse colon may be blocking your view. Apply constant downward pressure and rock your probe back and forth to displace bowel gas and get your window. If that doesn’t work, try placing your patient in the left lateral decubitus position or attempt the lateral views of the aorta.
Bowel Gas Impeding Aorta Ultrasound Visualization
Visualize the Celiac Trunk by sliding your probe slightly inferiorly.
The celiac trunk branches into the common hepatic artery and splenic artery in the “seagull sign” just anterior to the celiac trunk coming off the abdominal aorta.
The Seagull SignColor Doppler view of the Seagull Sign.
Visualize the superior mesenteric artery (SMA). Slide your probe inferiorly a bit further – it shouldn’t be far, since the SMA originates just distal to the celiac trunk. It will appear as a smaller, circular, hypoechoic structure just anterior to the abdominal aorta.
In this plane, you may also see the left renal vein between the SMA and the aorta, as well as the splenic vein anterior to the SMA.
These are the structures implicated in nutcracker syndrome when the left renal vein gets trapped between the aorta and SMA.
Left renal vein traveling between aorta and the superior mesenteric artery.
Measure the aorta in its widest diameter.
Freeze the image.
Take measurements from outer wall to outer wall at it’s widest diameter.
Obtain both an anteroposterior measurement and a transverse measurement if possible.