Aortic ultrasound

Technique

• Transverse
  • Start in epigastrium (below diaphragm) with indicator at 9 o'clock (aorta on left/IVC on right)
  • Use liver as window
  • Identify vertebral body (shadowing)
  • Rock/jiggle probe or hold steady pressure to move bowel gas from view
  • Scan from celiac to bifurcation (near umbilicus)
  • Capture and measure the largest diameter

• Sagittal
  • Rotate indicator to 12 o'clock (aorta on top/vertebra on bottom of screen)
  • Ensure you're looking at aorta and not IVC (aorta may pulsate/IVC may be compressible)
  • Scan from bifurcation to celiac
  • Capture and measure sagittal views, including the largest diameter
• Measurements
  • Normal is <3cm
  • Measure outer wall to outer wall (make sure to include thrombus)
  • Fusiform more common
    • Watch out for saccular aneurysms

Misc

• Obese Patients
  • Can try posterior approach

Findings

• Abdominal Aortic Aneurysm
  • >3cm diameter (transverse or saggital)
  • Look for free fluid
  • Try to reproduce pain with probe
  • If clot, confirm flow with doppler
  • Aorta may be lifted off spine 2/2 thrombus

• Aortic Dissection
  • Double lumen separated by intimal flap
  • Confirm with doppler

Pitfalls

• Preferred 9 to 3 o'clock measurements
  • Avoids posterior acoustic wall enhancement
  • Best wall to wall measurement
• AAA vs Dissection
  • Scan above and below area of concern
    • Dissections will continue while AAA typically are located in single area
    • Dissections can be a normal diameter

See Also

• Ultrasound (Main)
• AAA

Source

• Sonosite