Pseudoaneurysm: Causes, Locations, Risk Factors, and Treatment

Definition

A pseudoaneurysm (false aneurysm) is a contained hematoma communicating with an arterial lumen through a defect in the vessel wall. Unlike a true aneurysm, the arterial wall layers are not all intact; the outer adventitia or surrounding tissue forms the containing sac.

Common Causes

• Iatrogenic: Arterial catheterization (femoral access most common), endovascular procedures.
• Trauma: Penetrating (stab, gunshot), blunt (MVC, crush), fracture fragments.
• Infection: Mycotic aneurysm from bacteremia or contiguous spread.
• Vasculitis: Inflammatory wall weakening (polyarteritis nodosa, Kawasaki).
• Degenerative: Atherosclerosis, medial degeneration.
• IV drug use: Repeated arterial puncture.

Common Sites

• Femoral artery (post-catheterization: 0.1–2% incidence)
• Brachial artery
• Popliteal artery
• Visceral arteries (hepatic, splenic, superior mesenteric)
• Aorta (post-surgical, traumatic)

Risk Factors

• Anticoagulation/antiplatelet therapy
• Obesity (difficult compression)
• Large-bore sheaths, multiple punctures
• Hypertension, connective tissue disorders

Diagnosis and Treatment

• Duplex ultrasound (gold standard): "Yin-yang" flow, "to-and-fro" waveform.
• CT angiography for anatomic detail.
• Treatment: Ultrasound-guided thrombin injection (first-line), compression, covered stent, surgical repair.