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VascularBasic 3–5 min

Abdominal Aorta (AAA Screening)

Indication: AAA screening; flank/back pain in elderly; syncope with pain

How to Perform

  1. 1

    Patient supine. Use curvilinear probe. Start at the epigastrium just below xiphoid.

  2. 2

    Transverse view: identify aorta (left of midline, pulsatile, non-compressible). IVC is to the right and compressible.

  3. 3

    Sweep distally from diaphragm to bifurcation (at level of umbilicus, ~L4). Measure AP diameter in transverse at widest point.

  4. 4

    Measure outer-wall to outer-wall — this is the standard for AAA sizing.

  5. 5

    Longitudinal view: confirm diameter and assess for mural thrombus (echogenic crescent lining vessel wall).

  6. 6

    Look for periaortic hematoma (hypoechoic shadowing around aorta) — in the right clinical context this suggests rupture.

  7. 7

    Measure iliac arteries bilaterally if aorta is dilated. Normal iliac <1.5cm.

Measurement Guide

Abdominal Aortic Diameter

Where:Widest transverse outer-wall-to-outer-wall diameter. Measure at the level of maximum dilation — typically at or just below the renal arteries.
Normal:< 3 cm = normal; 3.0–5.4 cm = AAA (monitor); ≥ 5.5 cm = surgical threshold (men); ≥ 5.0 cm = surgical threshold (women)
Tip:ALWAYS measure in TRANSVERSE — sagittal views underestimate true diameter. Measure outer edge to outer edge (including walls). Check at the celiac axis, SMA origin, and just above bifurcation.

Iliac Artery Diameter

Where:Common iliac arteries bilaterally, transverse view, outer wall to outer wall at the widest point.
Normal:< 1.5 cm; ≥ 1.5 cm = iliac aneurysm
Tip:Trace the aorta to its bifurcation (level of umbilicus, ~L4). Evaluate both common iliac arteries. Iliac aneurysms often coexist with AAA.

Views to Obtain

  • Proximal aorta (subxiphoid transverse)
  • Mid aorta (transverse)
  • Distal aorta to bifurcation
  • Longitudinal aorta

What to Look For

  • Aortic diameter (AP + transverse)
  • Intraluminal thrombus
  • Periaortic hematoma
  • Iliac vessels

Common Mistakes

  • Measure outer wall to outer wall
  • Bowel gas obscuring view — gentle pressure or reposition
  • Don't confuse IVC for aorta

Pro Tip

Aorta is pulsatile and LEFT of midline; IVC is compressible and RIGHT of midline.

AI Detects

Dilation >3cm (aneurysm threshold)Dilation >5.5cm (surgical threshold)Intraluminal thrombusPeriaortic fluid
Start Scan — AAA

Protocol pre-selected · AI will use this context for analysis