Aorta and iliac vessels — arteries and veins

Aorta and iliac vessels — arteries and veins — Reference values: Abdominal aorta — maximum outer-to-outer diameter, Abdominal aortic aneurysm — usual repair threshold.

Dedicated category for the aortoiliac axis: screening/follow-up of abdominal aortic aneurysm, iliac artery aneurysm/ectasia, aortoiliac arterial stenosis, iliocaval venous obstruction and post-repair follow-up. Green = consensus normality; yellow = borderline zone, limited technique or divergent guidance; red = aneurysm, stenosis/occlusion, significant venous obstruction, growth, symptoms or complication.

Measurements and reference values

Measurement	Usual value	Note
Abdominal aorta — maximum outer-to-outer diameter	< 3,0 cm	Measure perpendicular to the vessel axis at the largest diameter. Aneurysm starts at 3.0 cm; ectasia 2.5-2.9 cm is a yellow zone.consensus normal: <2,5 cmectasia: 2,5–2,9 cmaneurysm: ≥3,0 cmSource: ACC/AHA 2022 / SVS / USPSTF / ESVS 2024
Abdominal aortic aneurysm — usual repair threshold	men ≥5.5; women ≥5.0 cm	Also consider vascular evaluation if symptomatic, saccular/pseudoaneurysm, rupture signs or rapid growth.surveillance: 3,0–4,9 cmnear threshold: 5,0–5,4 cmrepair threshold: ≥5.5 cm men; ≥5.0 cm womenSource: ACC/AHA 2022 / SVS / ESVS 2024
Common iliac artery — diameter	< 1.5-1.7 cm	There is divergence: ectasia may be defined from 1.5 cm in women or 1.7 cm in men; many services treat ≥2.0 cm as small aneurysm and ≥3.5 cm as a strong repair threshold.more consensual normal: <1,5 cmectasia/divergent: 1,5–1,9 cmiliac aneurysm: ≥2,0–2,5 cmdiscuss repair: ≥3,5 cmSource: ACC/AHA 2022 / ESVS 2024 / JVS isolated common iliac aneurysm
Aortoiliac arterial stenosis — velocity ratio	≥ 2,0	Ratio between jet velocity and normal proximal segment; use angle below 60 degrees and correlate with aliasing, narrowing and distal waveform.no hemodynamic stenosis: <1,5mild/technical zone: 1,5–1,99stenosis ≥50%: ≥2,0severe: >4,0Source: ACR-AIUM-SRU arterial Doppler / Society for Vascular Medicine / vascular lab criteria
Iliac/caval venous obstruction — velocity ratio	> 2,5	Useful but not absolute criterion: integrate with loss of common femoral phasicity, collaterals, extrinsic compression, thrombus, stent and symptoms.likely normal: <2,0 + onda fásicasuspicious/borderline: 2,0–2,5 ou onda pouco fásicasignificant obstruction: >2,5 ou colaterais/no flowSource: JVS Venous 2016 / ESVS 2022 / Labropoulos
Post-aortic endograft — aneurysm sac	stable or shrinking	Sac growth, endoleak, migration, kinking, limb thrombosis or absent iliac limb flow are warning signs.stable: sac stable/shrinking, no endoleaktype II endoleak without growth: follow per local protocolcomplication: type I/III, growth ≥5 mm, thrombosis/occlusionSource: SVU aortoiliac duplex / ACC-AHA 2022 / SVS

Classifications and calculators

Interactive assistant — aorta, iliac arteries and iliac/caval veins

Output	Color	Interpretation
Normal/preserved patency	Green	Aorta <2.5 cm, iliacs without relevant ectasia, arterial ratio <1.5, multiphasic arterial waveform and phasic/symmetric venous waveform.
Borderline, technical or divergent	Yellow	Aorta 2.5-2.9 cm, iliac 1.5-1.9 cm, poor window, venous ratio 2.0-2.5, mildly damped venous waveform or stable post-repair minor finding.
Aneurysm, stenosis, occlusion or obstruction	Red	Aorta ≥3.0 cm, iliac ≥2.0-2.5 cm, arterial ratio ≥2.0, no flow, venous ratio >2.5, collaterals, symptoms or endograft complication.

The assistant classifies ultrasound risk and documentation quality; final management depends on symptoms, sex, growth, anatomy, operative risk and local vascular protocol.

Source: ACC/AHA 2022 / SVS / ESVS 2024 / SVU / IAC / JVS Venous

Abdominal aorta — screening and follow-up

Maximum diameter	Color	Practical reading
<2,5 cm	Green	Normal in most adults; if screening was requested, record maximum measurement and visualized segment.
2,5–2,9 cm	Yellow	Ectasia: below classic aneurysm criterion but should be described; SVS suggests late rescreening when initial screening is >2.5 and <3.0 cm.
3,0–3,9 cm	Red	Small aneurysm; imaging surveillance is usually long-interval, for example 3 years in SVS.
4,0–4,9 cm	Red	Moderate aneurysm; closer surveillance, often yearly.
5,0–5,4 cm	Red	Large or near-threshold aneurysm; usually 6-month surveillance and vascular evaluation.
≥5.5 cm men or ≥5.0 cm women	Red	Usual repair threshold in current guidelines if anatomy and risk allow.

Source: SVS / ACC-AHA 2022 / USPSTF / ESVS 2024

Iliac arteries — diameter and aneurysm

Common iliac diameter	Color	Comment
<1,5 cm	Green	More consensual normality for teaching use.
1,5–1,9 cm	Yellow	Ectasia or divergent zone: some cutoffs vary by sex and body size.
2,0–2,4 cm	Yellow	Many studies call this small aneurysm; rupture risk is low, but documentation and comparison matter.
2,5–3,4 cm	Red	Established iliac aneurysm in radiology/vascular references; assess growth, bilaterality and associated aorta.
≥3,5 cm	Red	Strong threshold for repair discussion in ACC/AHA and ESVS, especially with concomitant aortic aneurysm.

Source: ACC/AHA 2022 / ESVS 2024 / JVS / Radiopaedia

Aortoiliac arterial stenosis — Doppler

Finding	Color	Interpretation
Velocity ratio <1.5 and multiphasic waveform	Green	No hemodynamically relevant stenosis in the assessed segment.
Ratio 1.5-1.99 or isolated jet without good reference	Yellow	Mild/technical zone: check angle, tortuosity, calcification and normal proximal segment.
Ratio ≥2.0, focal aliasing or damped distal waveform	Red	Compatible with hemodynamically significant stenosis, often ≥50%.
Ratio >4.0 or no flow	Red	Severe stenosis/occlusion; document extent, distal reconstitution and collaterals.

Source: ACR-AIUM-SRU arterial Doppler / Society for Vascular Medicine / SVU

Iliac veins and inferior vena cava — obstruction

Finding	Color	Interpretation
Phasic/symmetric common femoral waveform and patent cava/iliac veins	Green	Likely normal when the window is adequate and there are no collaterals.
Reduced phasicity, ratio 2.0-2.5 or unseen segment	Yellow	Suspicion/limitation: ultrasound may be indirect; integrate with unilateral edema, advanced CEAP and thrombosis history.
Venous ratio >2.5, collaterals, thrombus, absent flow or occluded stent	Red	Suggests significant iliocaval obstruction; consider CT venography, MR venography, venography or intravascular ultrasound depending on scenario.

May-Thurner/left common iliac vein compression may be underestimated on transabdominal ultrasound; do not exclude it if clinical suspicion is high.

Source: JVS Venous 2016 / ESVS 2022 / ACR venous guidance / Labropoulos

Post aortic/iliac repair — critical points

Scenario	Color	What to document
Sac stable or shrinking, no endoleak	Green	Maximum sac diameter, iliac limb patency and velocities without focal jet.
Type II endoleak without sac growth	Yellow	Probable location, sac flow and comparison with prior examinations; follow local protocol.
Type I/III endoleak, growth ≥5 mm, limb no-flow or migration	Red	Communicate as potentially relevant complication and suggest correlation with CT angiography/vascular service.

Source: SVU aortoiliac duplex / ACC-AHA 2022 / SVS

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