HCPCS Q4138: Wound matrixMedicare rate & RVUs

Medicare pays $127.26 for Q4138 nationally in the office. Local office rates run $109.31–$183.51.

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

What Q4138 covers

BioDflex DryFlex is a dehydrated amniotic tissue allograft supplied for placement over a prepared wound. Wound care clinicians, podiatrists, and surgeons may use it in outpatient wound clinics, physician offices, or hospital settings when treating wounds such as diabetic foot or venous leg ulcers. The product is placed on the wound bed as part of the treatment; the code represents the product, not the clinical work of preparing and treating the wound.

Report units on the code’s one-square-centimeter basis, and document the product used, wound site and dimensions, and the amount applied. CMS classifies Q4138 as an add-on code: report it only with a primary procedure, and its payment falls within that procedure’s global period. CMS also classifies it as technical-component-only, with a separate code covering interpretation.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where Q4138 pays more and less

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 of 109 payment localities

Q4138 rates by state

Office rate range in each state. Select a state to see its payment localities.

How the Q4138 rate is calculated

Each of Q4138’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

Payment rules and modifiers for Q4138

The CMS indicators that decide how Q4138 is paid alongside other services.

Q4138 compared with similar codes

How to choose

Q4140BioD-Fence

Use Q4138 for BioDflex DryFlex and Q4140 for BioDfence. The product name, not the shared area-based unit, distinguishes these codes.

Q4137Wound matrix

Q4137 identifies AmnioExcel or BioDExcel; Q4138 identifies BioDflex DryFlex. Both are area-based product codes, but they represent different products.

Q4139Amnio or biodmatrix, inj 1cc

Q4139 is for an injectable amniotic or BioDmatrix product measured by volume. Q4138 is for the dry BioDflex product measured by area.

Codes related to Q4138

Related codes aren’t interchangeable: bill the code that matches the service performed.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Open CMS sourceHow we calculate rates