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An iliac artery aneurysm (IAA) is a pathologic dilatation of the iliac artery, defined as a diameter >1.5 times the normal vessel size. It may involve the common iliac artery (CIA), internal iliac artery (IIA), or external iliac artery (EIA), with the common iliac artery being the most commonly affected.
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| Feature | Details |
|---|---|
| Age | Typically >65 years |
| Sex | Male > female (~5:1) |
| Laterality | Bilateral in ~30–50% of cases |
| Association | ~40% of patients with abdominal aortic aneurysm (AAA) also have IAA |
| Cause | Notes |
|---|---|
| Atherosclerosis (most common) | Degeneration of tunica media |
| Trauma or dissection | Pseudoaneurysm formation |
| Infection (mycotic aneurysm) | Rare; usually Salmonella or Staph aureus |
| Connective tissue disorders | Ehlers-Danlos, Marfan syndrome |
| Iatrogenic | Post endovascular/surgical interventions |
| Type | Comment |
|---|---|
| Isolated CIA aneurysm | Most common IAA; often associated with AAA |
| IIA aneurysm | May cause pelvic symptoms if compressive or ruptured |
| EIA aneurysm | Rare; tends to extend from adjacent aneurysmal disease |
| Presentation | Notes |
|---|---|
| Asymptomatic (most common) | Often found incidentally on imaging |
| Pulsatile abdominal mass | Possible on deep palpation |
| Lower abdominal, pelvic, or back pain | From mass effect or contained rupture |
| Ureteric obstruction/hydronephrosis | From ureteral compression (esp. IIA aneurysms) |
| Neurologic symptoms | Compression of adjacent nerves (e.g., lumbosacral plexus) |
| Acute rupture | Sudden hypotension, shock, retroperitoneal hemorrhage |
| Complication | Details |
|---|---|
| Rupture | Life-threatening; retroperitoneal hemorrhage |
| Thrombosis/embolism | Can cause acute limb ischemia |
| Compression effects | Ureteral obstruction, nerve compression, venous thrombosis |
| Fistulization | Rare; e.g., arteriovenous or ureteral fistula |
| Modality | Imaging features |
|---|---|
| CTA | • Fusiform or saccular dilation involving CIA, IIA, or EIA |
| • Wall calcifications: Common in atherosclerotic aneurysms | |
| • Thrombus within lumen: Frequently eccentric; seen as non-enhancing area | |
| • Perivascular stranding or hematoma: Suggests leak or rupture | |
| • Compression of adjacent organs: May displace ureters, veins, nerves | |
| US | • Useful for screening and follow-up in CIA aneurysms |
| • Limited for IIA or deep pelvic aneurysms | |
| MRA | • Alternative to CTA in patients with renal impairment |
| • Good for serial follow-up in elective cases |
Size criteria: