Diagnosing Arteriovenous Fistula (AVF) Infection
AVF infection is diagnosed primarily through clinical examination looking for localized signs of infection at cannulation sites, combined with blood cultures to identify bacteremia, as infections at the AV anastomosis itself are extremely rare. 1
Clinical Examination Findings
Inspect the access site systematically for the following signs:
- Erythema (redness) at or around cannulation sites 1
- Localized warmth to touch 1
- Swelling or edema at the access site 1
- Tenderness or pain with finger pressure 1
- Purulent drainage or discharge from cannulation sites 2
- Poor eschar formation at needle puncture sites 1
- Evidence of spontaneous bleeding 1
The vast majority of AVF infections occur at cannulation sites rather than at the arteriovenous anastomosis itself. 1, 2 Infections at the AV anastomosis are very rare but represent surgical emergencies. 1
Palpation and Auscultation
- Palpate for elevated skin temperature along the fistula 1
- Assess for pain caused by finger pressure over the access 1
- Check the quality of the thrill—absence or change may indicate thrombosis complicating infection 1
- Auscultate for changes in bruit character 1
Laboratory Evaluation
Obtain blood cultures immediately when AVF infection is suspected, particularly if systemic signs are present: 2
- Draw blood cultures from a peripheral site (not through the AVF) 2
- Obtain cultures before initiating antibiotics when possible 1
- Repeat blood cultures periodically during treatment and immediately after completing antibiotic therapy 2
Systemic Signs Requiring Urgent Evaluation
Monitor for signs of bacteremia or sepsis: 2
- Fever or chills 2
- Persistent bacteremia beyond 36 hours of appropriate antibiotic therapy 2
- Signs of metastatic complications (septic emboli, endocarditis) 1
Imaging Studies
Imaging is NOT routinely required for diagnosing AVF infection. 1 However, consider imaging in specific circumstances:
- Duplex ultrasound may help assess for complications like thrombosis or abscess formation 3, 4
- Imaging should be performed if there is concern for deep tissue involvement or anastomotic infection 1
Critical Distinctions
Differentiate AVF infection from other complications that may present similarly:
- Hematoma presents with discoloration, swelling, and altered intravascular pressure but without warmth or purulent drainage 5
- Thrombosis presents with loss of thrill and bruit but without inflammatory signs 1, 5
- Steal syndrome presents with pale/cold hand and pain, not warmth and erythema 6
Common Pitfalls to Avoid
- Do not delay evaluation or treatment—even minor signs of AVF infection require immediate initiation of antibiotics 2
- Do not confuse AVF infections (which are rare and usually at cannulation sites) with AVG infections (which are more common and often involve the graft material itself) 1, 2
- Do not miss anastomotic infections—though rare, they require immediate surgical intervention with resection of infected tissue 1
- Do not overlook the impaired immunologic status of dialysis patients, which makes any access infection potentially lethal 1
When to Suspect Anastomotic Infection (Surgical Emergency)
Anastomotic infections are very rare but require immediate surgical referral: 1