ABI Testing in Wound Care: When It's Required and How to Document It
Ankle-brachial index (ABI) testing in wound care — when Medicare requires it, how to perform and document it, and how it affects compression and skin substitute coverage.
Damon Ebanks
Medipyxis
ABI Testing in Wound Care: Requirements and Documentation
ABI (ankle-brachial index) is one of the most commonly missing elements in wound care denials and post-payment audits. The requirement is straightforward. The execution is simple. Yet a significant percentage of denied skin substitute and advanced therapy claims trace back to a missing or expired ABI.
This is not a vascular surgery issue. Documenting and obtaining ABI is part of the wound care specialist's standard protocol for every lower extremity wound.
When ABI Is Required
Any lower extremity wound patient (DFU, VLU, arterial ulcer, pressure injury on lower extremity): ABI required before:
- Initiating compression therapy
- Applying a skin substitute or advanced therapy (CTP)
- Billing E/M for ongoing lower extremity wound management at most MACs
Frequency: Most MAC LCDs accept ABI performed within 90 days of the service date. Some MACs specify 30 days for specific services. Review your MAC billing article.
How to Perform ABI in a Mobile Setting
ABI requires a handheld Doppler probe and a blood pressure cuff. Both are portable and standard for mobile wound care kits.
Equipment: 8–10 MHz handheld Doppler probe ($150–$400), standard BP cuff, stethoscope.
Measurement steps:
- Patient supine for 10 minutes prior
- Measure brachial systolic pressure: both arms, use the higher reading
- Apply BP cuff to ankle above the malleoli
- Place Doppler probe at posterior tibial artery OR dorsalis pedis artery
- Inflate cuff, deflate slowly, record systolic pressure at first audible signal return
- Calculate: ABI = ankle systolic ÷ brachial systolic
Bilateral: Always measure both legs even if the wound is unilateral. Document both readings.
Interpreting ABI Results
| ABI Value | Interpretation | Clinical Action |
|---|---|---|
| 1.0–1.3 | Normal | Compression safe |
| 0.8–0.99 | Mild-moderate CVI | Compression safe; vascular follow-up recommended |
| 0.5–0.79 | Moderate PAD | Modified compression only; vascular referral |
| <0.5 | Severe PAD | Compression contraindicated; urgent vascular referral |
| >1.3 | Calcified arteries (non-compressible) | ABI unreliable; order toe-brachial index or vascular lab |
Documentation That Satisfies LCD Review
Your note must include:
- Date of ABI measurement
- Brachial systolic pressure (value and side)
- Ankle systolic pressure (right and left, PT and DP arteries if both measured)
- Calculated ABI values (right and left)
- Clinical interpretation
- Action taken based on result (e.g., "ABI 0.9 bilaterally, compression therapy initiated at 30–40 mmHg")
If the patient has calcified arteries and ABI is non-compressible (>1.3), document that you are ordering a toe-brachial index or referring to vascular lab. "Non-compressible arteries, toe-brachial index ordered, vascular surgery consulted" is defensible. "No ABI on file" is not.
Billing ABI
CPT 93922: Noninvasive physiologic study of upper or lower extremity arteries, single level, bilateral (~$80). Billable when you perform a formal ABI study.
CPT 93923: Complete bilateral noninvasive physiologic study (~$130).
Not all payers reimburse these codes in the context of wound care visits — confirm with your MAC and commercial payers before billing routinely.
Related: VLU Wound Care Guide | DFU Guide | WiSeR Model | Documentation Requirements