Can Pseudoaneurysms Become Suppurative?
Yes, pseudoaneurysms can become infected and suppurative, representing a life-threatening complication that requires urgent surgical intervention with extensive debridement and prolonged antimicrobial therapy.
Mechanism of Infection
Pseudoaneurysms can develop suppurative infection through several pathways:
- Direct contamination during the initial arterial injury, particularly in cases of arterial puncture during intravenous drug abuse 1
- Hematogenous seeding in patients with catheter-related bloodstream infections, where infected thrombus can seed the pseudoaneurysm 1
- Erosion from adjacent infection, such as deep cervical abscesses that can mask underlying infected pseudoaneurysms 2
The infectious arteritis leads to progressive destruction of the arterial wall with formation of a blind, saccular outpouching that communicates with the arterial lumen 3.
Clinical Presentation of Infected Pseudoaneurysms
Infected pseudoaneurysms present with distinct features that differentiate them from non-infected lesions:
- Variable inflammatory response ranging from minimal to significant localized inflammation 4
- Draining sinus tract is highly suggestive of underlying vascular graft infection with pseudoaneurysm 4
- Perivascular soft-tissue mass or edema on imaging, with uncommon findings including perivascular gas 3
- Persistent bacteremia or fungemia despite appropriate antimicrobial therapy and catheter removal 1
The presentation can be deceptive, as infected pseudoaneurysms may be masked by excessive inflammation of surrounding tissues, leading to misdiagnosis as simple abscesses 2.
Causative Organisms
Staphylococcus aureus is the most common offending organism in suppurative pseudoaneurysms:
- S. aureus predominates in catheter-related suppurative thrombophlebitis with associated pseudoaneurysm formation 1
- Patients undergoing chemotherapy for malignancy and those with solid tumors who develop S. aureus catheter-related bloodstream infection are at increased risk 1
- Nearly 60% of infected carotid pseudoaneurysms are associated with Staphylococcal infection 5
Management of Infected Pseudoaneurysms
Surgical Approach (Primary Treatment)
Infected femoral pseudoaneurysms must be treated by extensive operative debridement, often in conjunction with either autogenous in situ reconstruction or extra-anatomic bypass grafts 1. The surgical approach includes:
- Resection of infected tissue with wide debridement of all necrotic and infected material 1
- Autogenous vein reconstruction (great saphenous vein interposition) is the safest treatment in infected pseudoaneurysms, as synthetic grafts should be avoided in contaminated fields 5
- Extra-anatomic bypass may be necessary to avoid critical limb ischemia when direct reconstruction is not feasible 1
For dialysis AV graft pseudoaneurysms, resection and insertion of an interposition graft is indicated when the pseudoaneurysm is infected 1.
Antimicrobial Therapy
Prolonged antimicrobial therapy is essential:
- Minimum 3-4 weeks of systemic antimicrobial therapy for suppurative thrombophlebitis with pseudoaneurysm 1
- Parenteral antibiotics should be initiated immediately upon diagnosis 5
- Organism-specific therapy based on culture results, with empiric coverage for S. aureus pending cultures 1
Endovascular Approach Contraindication
The endovascular approach must be performed only in proven non-infectious cases 5. Placing synthetic stent grafts in infected pseudoaneurysms risks:
- Persistent infection with inability to clear bacteremia
- Stent graft infection requiring subsequent removal
- Potential for catastrophic rupture
A bridge technique with temporary stent insertion followed by open surgical repair can be considered only in emergency hemorrhage situations 5.
Critical Pitfalls to Avoid
- Misdiagnosis as simple abscess: Infected pseudoaneurysms can be confused with abscesses, leading to attempted drainage that results in catastrophic hemorrhage 2
- Delayed recognition: Physical examination alone misses more than 60% of pseudoaneurysms; imaging with duplex ultrasound or CT angiography is essential when infection involves vascular structures 1, 4
- Inadequate imaging review: Small infected pseudoaneurysms may be overlooked on initial CT imaging, requiring careful review when clinical suspicion is high 2
Complications of Untreated Infected Pseudoaneurysms
Delayed or inadequate management carries high morbidity and mortality: