Can a primary care provider perform an ankle‑brachial index (ABI) in the office, or is referral to vascular surgery required?

Primary Care Providers Can and Should Perform ABI Testing In-Office

Primary care providers should perform ankle-brachial index (ABI) testing directly in their office setting without requiring referral to vascular surgery for this diagnostic test. 1

Who Can Perform ABI Testing

The American Heart Association explicitly states that the ABI should be performed by qualified individuals, including physicians, nurses, vascular technicians, and other allied health professionals who have received proper training. 1, 2 This is not a procedure restricted to vascular specialists—it is designed for frontline primary care implementation.

Training Requirements

• Training should consist of both didactic and experiential learning, with basic knowledge of vascular anatomy, physiology, clinical presentation of PAD, and understanding of how a Doppler device functions. 1
• Trainees must demonstrate correct independent performance of each step in both healthy individuals and those with PAD, with reproducible results and correct calculation/interpretation. 1
• The actual performance time averages 5 minutes (range 3-11 minutes), with 84% of procedures completed in under 6 minutes. 3

Why Primary Care Should Perform ABI

• The ABI is recommended as the first-line noninvasive test for diagnosis of PAD when there is clinical suspicion based on symptoms and findings (Class I, Level of Evidence A). 1
• Peripheral arterial disease is severely underdiagnosed in primary care despite affecting over 8 million Americans and being associated with increased cardiovascular morbidity and mortality. 4, 3
• After participation in structured ABI training programs, primary care clinician use increased from 12% to 43% weekly and 13% to 39% monthly, with 96% believing it was useful for symptomatic PAD and 89% for asymptomatic disease. 4

Equipment and Setup

• A handheld continuous-wave Doppler probe (8-10 MHz) with gel and standard blood pressure cuffs are the only equipment required. 5, 2
• The test can be successfully performed by office staff commonly found in primary care settings after appropriate training. 6

When to Refer to Vascular Surgery

Referral to vascular surgery is indicated for management decisions, not for the diagnostic ABI itself:

• When ABI ≤0.90 or TBI <0.70 confirms PAD in a symptomatic patient requiring anatomic imaging (duplex ultrasound, CTA, or MRA) for lesion localization and revascularization planning. 5
• When ankle pressure <50 mm Hg or ABI <0.5 suggests need for revascularization consideration. 5
• When non-healing ulcers persist despite optimal wound care with abnormal vascular studies. 5
• When exercise ABI confirms PAD and symptoms warrant intervention. 5

Critical Technical Points

• Position patient supine for 10 minutes before measurement to allow hemodynamic stabilization. 1, 5, 2
• Measure both brachial pressures; use the higher value as the denominator for all ABI calculations. 5, 2
• For each leg, use the higher of dorsalis pedis or posterior tibial pressure as the numerator for diagnostic purposes (maximizes specificity 0.99 vs 0.93). 2
• Calculate ABI separately for each leg: ABI = higher ankle pressure ÷ higher brachial pressure. 5, 2

Interpretation Thresholds

ABI Value	Interpretation	Action
≤0.90	Confirms PAD	Initiate cardiovascular risk reduction; consider vascular referral if symptomatic
0.91-0.99	Borderline	Obtain exercise ABI or TBI
1.00-1.40	Normal (but unreliable in diabetes)	Obtain TBI in diabetic patients regardless
>1.40	Non-compressible vessels	TBI mandatory; ABI invalid

1, 5

Common Pitfalls in Primary Care

• Inaccurate measurement technique: A study of 99 patients from 45 primary care practices demonstrated great variability between primary care ABI measurements and vascular laboratory standards, due to inconsistent blood pressure measurement methods and calculation errors. 7
• Relying on pulse palpation alone: Pulse palpation for ABI measurement has poor intra-observer reproducibility (R=0.60 vs 0.89 for Doppler) and inter-observer reproducibility (R=0.40 vs 0.79 for Doppler), and cannot be recommended. 8
• Using automatic oscillometric devices without validation: Automatic devices show poor inter-observer reproducibility (R=0.44) compared to Doppler (R=0.79) and cannot replace standard Doppler technique. 8
• Skipping TBI in diabetic patients: Medial arterial calcification in diabetes produces falsely normal or elevated ABI values despite significant stenotic disease; TBI must be obtained regardless of ABI result. 5

Barriers and Solutions

The primary barriers identified by primary care clinicians are time constraints (56%), lack of reimbursement (45%), and staff availability (45%). 4 However, 88% of clinicians believed it was feasible to incorporate ABI into daily practice after training, and 57-75% believed ABI was equal to or more useful than other widely available screening tests. 4

Solution: Delegate ABI performance to trained medical assistants or nurses, schedule dedicated time slots for vascular screening, and bill appropriately using CPT code 93922 (non-invasive physiologic studies of upper or lower extremity arteries).