Skin in the game: Auditing Skin Grafting Services
This auditing and compliance “Tip of the Week” was originally published by the National Alliance for Medical Auditing Specialists (NAMAS), a division of DoctorsManagement.
Skin replacement codes, which are selected based on body areas, patient age, and wound measurements, can be intimidating even to experienced coders and auditors. Apart from choosing the correct graft code for skin replacement, there are also codes for surgical preparation services, which require clear documentation and are often billed with insufficient documentation, or for services that are considered inclusive to the grafting procedures themselves.
Let’s demystify these services and examine what auditors should be looking for when reviewing operative notes.
Types of grafts
First, there are two categories of skin graft materials: autografts, which are obtained from an undamaged area of the patient’s body, and skin substitute grafts, which span a wide variety of possible substitutes, ranging from the skin of human cadavers to animal skin (typically taken from pigs) or synthetic materials.
Allografts and xenografts provide only temporary covering – they are rejected by the patient’s immune system within seven to 10 days and must be replaced with an autograft at that point.
In this article, we will focus on split- and full-thickness autografts. A split-thickness skin graft is composed primarily of epidermis (outer layer of skin tissue) and some of the dermis (innermost tissue) and usually heals quickly, within several days of grafting. Split-thickness grafts are usually applied to shallow wounds because the grafted tissue must be fed by blood vessels from within the dermis of the wound area. The CPT codes for split-thickness autografts are 15100-15136. These codes describe autografts of epidermis and dermis to the body using two metrics based on patient age. Units of 100 sq cm are used for adults (defined as patients 10 years of age or older). The units for infants and children (defined as patients under 10 years of age) use percentage of total body area.
Full-thickness grafts involves both the epidermis and dermis and are used for the most serious wounds such as full-thickness (third degree) burns of the skin. Because they are composed of both layers of skin, full-thickness autografts can better conform to the wound graft site and tend to offer better cosmetic results as well. However, full-thickness grafts involve a larger wound area which often requires surgical preparation as well as post-grafting wound care. The donor site from which the full-thickness graft is harvested will itself require a split-thickness graft to promote proper healing and recovery. The CPT codes for full-thickness autografts include 15240-15261. Crucially, these codes differ from the split-thickness codes in that they a.) do not differentiate between patients by age and b.) they use units of 20 sq cm rather than 100 sq cm or percentage of body area. Like the split-thickness graft codes, they are divided into groups by anatomic site.
For both types of grafts, closure of the donor site after harvesting of the graft tissue is considered a separate procedure and can be reported with a separate code. The appropriate repair/closure code would be used (12001-13160). Closure of the graft recipient site is bundled and not separately billable.
Surgical preparation (CPT 15002-15005)
The recipient site on the patient’s body, which is where the graft will be placed, must be free of infection, disease, and debris. To that end, surgical preparation services may be required. The surgical prep codes received revised CPT guidelines in 2012. While they are primarily billed alongside skin grafting procedures when the recipient sites require extensive preparation, these codes can also be billed prior to negative pressure wound therapy (NPWT) services.
Surgical prep codes carry significant reimbursement (comparable to muscular- and bone-level excisional debridement codes 11043 and 11044), which is one reason some providers are tempted to report them for any type of pre-procedural work. Remember that any typical pre- and post-procedure work is considered inclusive to the procedure code. Surgical preps are billable only when significant additional work to prepare the recipient site is necessary. For example, if a patient with significant burns on his arms requires debridement of the burn site down to viable subcutaneous tissue in order to receive an autograft, this is significant additional work that may be reported as surgical preparation (15002).
Note that the surgical preparation codes and not excisional debridement codes should be reported in this scenario. The debridement codes are bundled with the grafting codes under the National Correct Coding Initiative (NCCI) edits.
Top mistakes to look for
Despite their apparent complexity, when auditing skin grafting services there are two major sources of error (in addition to missing or insufficient documentation of the graft type and procedure).
- Wound measurements are inaccurate. There are a lot of ways wound measurements can cause graft coding to go wrong. Apart from errors in arithmetic, you should also be on the lookout for wound sums that are combining measurements from different anatomic sites. For example, wounds from the face should not be lumped in with wounds of the arms and trunk. This applies both to grafting codes and to surgical preparation codes.
- Surgical preparation isn’t sufficiently documented. This can include notes where surgical preparation was done, but not adequately documented, or cases where the services rendered prior to grafting did not rise to the standard of work required to support billing of surgical preparation.
This Week’s Audit Tip Written By:
Grant is director of content at NAMAS. He has worked for years as a healthcare regulatory analyst and producer of educational content. A certified coder and auditor, Grant also serves as a compliance consultant at our parent company, DoctorsManagement, LLC.
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