Abdominal Aortic or Iliac Aneurysms
Measure / Define
AAA definition
Infrarenal abdominal aortic aneurysm is diameter >=3.0 cm or approximately >=1.5 times expected normal diameter.
Report
- Maximum outer-wall-to-outer-wall diameter, measured perpendicular to the vessel axis.
- Location: suprarenal, juxtarenal, infrarenal, common iliac, internal iliac, or external iliac.
- Mural thrombus, calcification, saccular morphology, inflammatory change, leak, rupture, or dissection if present.
- Relationship to renal arteries, aortic bifurcation, iliac bifurcation, and prior repair grafts/stents.
Normal / ectatic
- Typical suprarenal aorta: up to about 3.0 cm.
- Typical infrarenal aorta: about 2.0 cm.
- Aortic diameter <2.5 cm generally needs no imaging follow-up.
- Diameter 2.5-2.9 cm is ectatic: follow-up imaging about every 5 years.
AAA Follow-Up
Initial surveillance intervals
Use the largest comparable diameter. Shorten intervals when growth rate, symptoms, morphology, or comorbidity increases concern.
Infrarenal aorta
- 3.0-3.4 cm: follow-up every 3 years.
- 3.5-3.9 cm: follow-up every 2 years.
- 4.0-4.4 cm: annual follow-up.
- 4.5-4.9 cm: follow-up every 6 months.
- 5.0-5.5 cm: follow-up every 3-6 months and consider vascular surgery or endovascular referral.
Escalate
- Symptoms attributable to aneurysm, periaortic stranding, leak, rupture, or rapid enlargement.
- Saccular aneurysm or suspected infectious/inflammatory aneurysm.
- Complex anatomy involving visceral/renal branches or prior repair.
- Any aneurysm near treatment threshold should be clearly flagged in the impression.
Iliac Aneurysms
Definition
Iliac artery aneurysm is diameter >=2.5 cm or approximately >=1.5 times expected normal diameter.
Report
- Which iliac artery is involved: common, internal, or external.
- Maximum diameter and whether the aneurysm is fusiform or saccular.
- Internal iliac involvement, branch aneurysm, thrombus, rupture signs, or associated AAA.
- Prior endovascular repair, endoleak, sac size, or graft limb complications when relevant.
Follow-up / referral
- Common iliac aneurysm 3.0-3.5 cm: CT or MR follow-up at about 6 months.
- Larger iliac aneurysms require closer follow-up or vascular treatment planning.
- Referral is appropriate for symptomatic, enlarging, saccular, ruptured, or large iliac aneurysms.
- When an AAA and iliac aneurysm coexist, management is usually driven by the most clinically important lesion and repair anatomy.