Cause of Upper Extremity Pseudoaneurysm
The most common cause of upper extremity pseudoaneurysm is penetrating trauma, particularly from gunshot wounds and stab wounds, which together account for the majority of cases in reported series. 1
Primary Etiologies
Penetrating Trauma (Most Common)
- Gunshot wounds and stab wounds are the predominant causes, with one surgical series reporting 44% from gunshot wounds and 56% from stab wounds among patients with brachial artery pseudoaneurysms 1
- Even minor penetrating trauma from metal fragments can result in significant pseudoaneurysm formation, though diagnosis may be delayed due to the deep anatomic location of upper extremity vessels 2
- Patients often present weeks to months after the initial injury (mean 26.7 months in one series, ranging from 17 months to 7 years), as symptoms develop gradually 1
Iatrogenic Causes (Less Common in Upper Extremity)
- While iatrogenic injury from arterial catheterization is the most common cause of pseudoaneurysms overall, this predominantly affects the femoral artery rather than upper extremity vessels 3, 4
- Upper extremity iatrogenic pseudoaneurysms can occur from arterial line placement, cardiac catheterization via radial access, or other percutaneous procedures, but are far less frequent than in the groin 3
Intravenous Drug Use
- In the lower extremities, particularly the femoral vessels, intravenous drug use is a major cause of pseudoaneurysms with associated infection (mycotic aneurysms) 3
- Upper extremity pseudoaneurysms from IV drug use are less commonly reported but can occur, often with polymicrobial infection including MRSA 3
Important Clinical Context
The upper extremity differs fundamentally from the lower extremity in pseudoaneurysm etiology. While femoral artery pseudoaneurysms are predominantly iatrogenic (from the exponential growth of interventional cardiology procedures using femoral access), upper extremity pseudoaneurysms remain primarily traumatic in origin 3, 1, 4
Key Diagnostic Considerations
- Patients present with a pulsatile mass, often with pain radiating along the extremity 1, 5
- Physical examination reveals a thrill or bruit in most cases 5
- Diagnosis requires imaging confirmation with color-flow Doppler ultrasound showing the characteristic "to-and-fro" flow pattern, as physical examination alone misses >60% of pseudoaneurysms 3, 6
- Selective digital subtraction angiography provides definitive anatomic detail for surgical planning 1
Critical Pitfall to Avoid
Do not dismiss minor trauma as insignificant—even seemingly trivial penetrating injuries can cause delayed presentation of large pseudoaneurysms weeks to years later, particularly in the brachial artery distribution where symptoms may be subtle initially 1, 2