What is the test of choice to check for blood flow in a patient with suspected peripheral artery disease?

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Test of Choice for Blood Flow in Suspected Peripheral Artery Disease

The ankle-brachial index (ABI) is the test of choice to check for blood flow in patients with suspected peripheral artery disease. 1

Initial Diagnostic Approach

The resting ABI is the cornerstone initial diagnostic test for establishing the diagnosis of PAD and should be performed in all patients with history or physical examination findings suggestive of PAD. 1 This simple, noninvasive test measures systolic blood pressures at the brachial arteries and ankles (dorsalis pedis and posterior tibial arteries) using a Doppler device in the supine position. 1

ABI Interpretation

  • Abnormal: ≤0.90 (confirms PAD diagnosis) 1
  • Borderline: 0.91-0.99 1
  • Normal: 1.00-1.40 1
  • Noncompressible: >1.40 (requires alternative testing) 1

When ABI is Not Appropriate: Alternative Tests

For Noncompressible Vessels (ABI >1.40)

The toe-brachial index (TBI) should be measured when the ABI is >1.40, which typically occurs in patients with medial arterial calcification, particularly those with long-standing diabetes or advanced chronic kidney disease. 1, 2 A TBI <0.70 is considered abnormal and diagnostic of PAD. 1, 2

Additional perfusion assessment options include:

  • Transcutaneous oxygen pressure (TcPO₂): Values <30 mmHg suggest critical limb-threatening ischemia 1
  • Skin perfusion pressure (SPP): Values ≥30-50 mmHg associated with wound healing likelihood 1, 2
  • Pulse volume recordings (PVR) with Doppler waveforms: Useful for establishing diagnosis and localizing disease 1, 2

For Normal or Borderline ABI with Symptoms

Exercise treadmill ABI testing is recommended for patients with exertional non-joint-related leg symptoms and normal or borderline resting ABI (>0.90 and ≤1.40) to differentiate arterial claudication from pseudoclaudication. 1 This test objectively measures functional limitations and provides diagnostic confirmation when resting studies are equivocal. 1

Anatomic Assessment for Revascularization Planning

When revascularization is being considered, anatomic imaging is required:

  • Duplex ultrasound: First-line imaging with 85-90% sensitivity and >95% specificity for detecting stenosis >50% 1, 2
  • CTA or MRA: Useful for anatomic characterization and revascularization planning 1, 2
  • Invasive catheter angiography: Reserved for patients with chronic limb-threatening ischemia in whom revascularization is considered 1

Critical Caveat

Invasive and noninvasive angiography should NOT be performed for anatomic assessment in patients with asymptomatic PAD, as there is no evidence this improves outcomes. 1, 2

Segmental Localization

Segmental leg pressures with PVR and/or Doppler waveforms are reasonable to perform in addition to the resting ABI when anatomic localization is needed to create a therapeutic plan (e.g., differentiating aortoiliac from femoropopliteal disease). 1

Common Pitfall to Avoid

The most important pitfall is relying solely on ABI in patients with diabetes or advanced age, as these patients frequently have noncompressible vessels that yield falsely elevated ABI values (>1.40). 1, 2 In these cases, proceeding directly to TBI with waveforms prevents diagnostic delay. 1, 2

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Guideline

Ankle-Brachial Index (ABI) Appropriateness and Alternative Diagnostic Methods

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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