Medicare will not pay for a skin substitute graft, hyperbaric oxygen therapy, or another advanced wound therapy on a diagnosis alone. Every Medicare Administrative Contractor (MAC) coverage policy governing these products starts from the same premise: the wound must first fail a documented trial of conservative wound care. For skin substitute grafts and cellular and tissue-based products (CTPs), that trial is commonly four weeks. For hyperbaric oxygen therapy, a separate national coverage policy requires 30 consecutive days without measurable healing, reassessed every 30 days after that. Providers who bill for advanced therapy without a clean record behind the trial are the ones losing claims on audit.
What Counts as Conservative Care
Conservative care under these policies is a defined bundle of interventions, not general wound cleaning. For a diabetic foot ulcer, it means debridement of nonviable tissue, offloading the wound with a total contact cast, walking boot, or similar device, a moist wound-healing environment maintained through appropriate dressings, treatment of any active infection, and correction of vascular insufficiency where the patient's anatomy allows it, alongside glucose and nutritional management. For a venous leg ulcer, compression therapy replaces offloading as the anchor intervention, alongside the same debridement, moist dressing, and infection-control elements. The relevant local coverage determination treats this period as the evidence that the wound actually needed the advanced product, not as a formality to clear before ordering one.
The Trial Period and the Failed-to-Respond Standard
The commonly cited figure for skin substitute grafts and CTPs is four weeks, and it appears in the Medicare Administrative Contractor local coverage determinations still active nationwide, including CGS's L36690, Novitas's L35041, and First Coast's L36377. Under these policies, a wound has failed to respond when it has not decreased in size or depth, or shows no measurable sign that closure is likely, such as new granulation tissue or an advancing epithelial margin, despite four weeks of the interventions above with the patient compliant. That figure is not universal across every advanced wound therapy. Hyperbaric oxygen therapy is covered under a separate national coverage determination that sets its own standard: no measurable sign of healing for at least 30 consecutive days of standard wound care, reassessed every 30 days for as long as treatment continues. A patient receiving both therapies needs two separate conservative care records, not one.
Documentation That Survives Audit
A conservative care trial that exists only in a provider's memory does not survive audit. The wound needs a measured baseline, length, width, and depth, recorded before conservative care starts, a measurement at the end of the trial period, and a measurement taken immediately before the first graft application or hyperbaric session. Each conservative-care visit needs a dated note tying the specific intervention, debridement, a dressing change, an offloading device fitting, to that date, corroborated by a signature log identifying who performed it. See Wound Care LCD Compliance: Coverage Criteria by Documentation Element for the full list of elements each MAC checks. Skin substitute billing drew heavy Medicare scrutiny through 2025, and Medicare Administrative Contractors and Unified Program Integrity Contractors reviewing 2026 claims are applying these local coverage determinations as the operative standard, in some cases against providers located outside the issuing MAC's own jurisdiction. Providers already answering a UPIC Audits of Wound Care Practices: What Triggers Them request, or sitting inside a Wound Care Prepayment Review: Documentation That Releases Claims hold, are seeing this same four-week question asked first.
The four-week trial is not paperwork cleared before the graft goes on. It is the evidence a Medicare Administrative Contractor uses to decide whether the therapy was medically necessary at all.
Why Early Legal Counsel Is Critical
It is critical that wound care providers promptly retain experienced healthcare defense counsel upon receiving an audit notice, a documentation request, or a prepayment hold tied to skin substitute or hyperbaric oxygen claims. Early legal intervention can protect the provider's rights, ensure the conservative care record is assembled and presented correctly before a response deadline passes, preserve challenges to a Medicare Administrative Contractor's application of another jurisdiction's local coverage determination, and allow counsel to communicate with reviewers on the provider's behalf. Delaying legal representation can significantly affect the outcome of a matter and expose the practice to recoupment it could otherwise avoid.
How Health Law Alliance Can Help
Health Law Alliance represents wound care providers nationwide in wound care audit defense, including skin substitute and hyperbaric oxygen claim reviews, UPIC and MAC documentation requests, and prepayment review appeals. If your practice is facing a wound care audit or a denial tied to conservative care documentation, contact us today for a free consultation.
