Complex repairs

Cracking the Code

Alexander Miller

Dr. Miller, who is in private practice in Yorba Linda, California, represents the American Academy of Dermatology on the AMA-CPT Advisory Committee.

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You excise a basal cell carcinoma on the cheek. In order to optimize functionality and cosmesis you undermine the surgical edges and suture the wound in a layered fashion. Do you bill for an intermediate repair (layered closure) or a complex repair?

This type of question often challenges dermatologists and their coding and billing staff. Complex repair (CPT codes 13100 — 13153) is defined as a repair that requires more than layered closure, such as scar revision, debridement (as of traumatic lacerations), extensive undermining, stents, or retention sutures. In dermatology the overriding use of the code is for repairs of surgical excisions of malignant and benign tumors. Such repairs may require extensive undermining or retention sutures. [pagebreak]

What is extensive undermining?

The American Medical Association Current Procedural Terminology (AMA/CPT) does not define the term “extensive undermining.” Interpretation of extensive undermining is left to the judgment of the surgeon to determine, and the payer to apparently confirm via reimbursement for the procedure. Any attempt to further define extensive undermining risks imposing rigid and impractical values that would not reflect real-life work. There are, however, some common-sense concepts that may aid in coding.

Clearly, the breadth of undermining done on a nose or eyelid will be different from the amount of undermining needed on a scalp or back to fulfill the concept of extensive undermining. It is up to the surgeon to ethically decide when undermining has reached the “extensive” category. The billing of complex repair codes has steadily increased over the past several years. For example, according to Medicare data for 2011, utilization of CPT code 13101 (Repair, complex, trunk; 2.6 cm to 7.5 cm) increased by almost 9 percent from 2010. Continued high utilization risks regulation and focused chart audits. To report complex repair codes, the medical record must document that extensive undermining was done and should provide justification for its need.

Retention sutures are occasionally necessary for wound closure. The characteristic patient is elderly and has a large lesion excised from an upper or lower extremity with severely photodamaged and atrophic skin. Such atrophic skin may be too thin to hold buried dermal sutures and will readily rip. Yet, due to tension across the excision wound, simple interrupted stitches alone would also tear the skin and would fail to hold the wound shut. Exteriorized broad horizontal mattress retention sutures placed far from the wound edge and padded with a material of choice to prevent notching are successfully used to reduce tension and approximate the skin edges. [pagebreak]

How do stents relate to dermatology?

The present-day concept of “stent” usually refers to a material inserted into a tube-like body structure, such as a vessel or a duct, for the purpose of maintaining patency of the tube. This definition does not make any sense in the context of complex repairs. Charles R. Stent, an English dentist, invented and patented a moldable dental impression compound in 1856. This same compound was subsequently used by a Dutch plastic surgeon during World War I for the fixation of intraoral and cutaneous grafts and called a “stent.” The term has stuck and is used widely. You may read more about the history of “stent” at

For dermatologic purposes, a stent is a moldable material used for tissue compression for the purpose of holding down the tissue, such as a skin graft. Repair scenarios where a stent compression may be required would be lacerations with a partial thickness skin avulsion where the laceration itself would be sutured shut and then the partially avulsed skin draped over the dermis and fixated with a compression stent.

Complex repair codes do not include the excision of the lesion. The excision should be billed separately with the appropriate malignant (11600 — 11646) or benign (11400 — 11446) excision code. [pagebreak]

Finally, the repair location and the measured length of the repaired wound are used for selecting the proper complex repair CPT code. Note that when the repair length reaches beyond 7.5 cm in any location an additional code, marked by a “+” sign in the CPT, is used to specify the increased length. This add-on code specifies increments of up to 5 cm beyond a 7.5 cm closure length, and may be used in multiples to list the appropriate closure length. When more than one wound is closed in the same CPT-defined anatomical grouping, the lengths of the repairs are added together to produce the appropriate billing code. Complex repairs done on sites lying within separate CPT anatomical groupings are measured and reported separately, with the less complicated repair assigned a 59 modifier.

Example 1

You excise a cheek basal cell carcinoma with two stages of Mohs surgery, leaving a 1.5 cm diameter defect. The wound is fashioned into a vertically oriented 4 cm long fusiform shape via excisions of skin triangles bordering the superior and inferior Mohs defect edges. The wound edges are undermined to facilitate skin edge eversion and a layered repair is done. You bill 17311 and 17312 for the Mohs surgery and 13132 for the complex repair.

Incorrect. The act of undermining alone does not justify a complex repair code. The undermining has to be “extensive” to qualify for a complex closure. The excision of redundant skin required to facilitate a linear repair following the Mohs surgery is not separately billable as an excision, and by itself does not determine a complex repair, as per the CPT definition. In this scenario the undermining was minimal, and a layered repair was done. Consequently, this falls into the intermediate repair category. The length of the repair generated by the final closure determines the intermediate repair code selection, which in this case would be 12052. [pagebreak]

Example 2

A patient has a squamous cell carcinoma excised from his thigh resulting in a 3.3 cm maximum excision diameter and a basal cell carcinoma excised from his dorsal nose with a 1.2 cm maximum excision diameter. Both are repaired linearly, with extensive undermining needed to close both surgical defects. The nasal undermining extends to the nasofacial sulcus bilaterally. The lines of closure measure 9 cm on the thigh and 3.2 cm on the nose. The bill lists 11604 for the thigh excision and 13121 plus 13122 for the complex repair along with 11642/59 for the nose excision and 13152/59 for the repair.

Correct. The excisions are billed separately, as the complex repair codes do not include valuation for the excisions. Since the complex repairs are located on separate anatomic site CPT groupings (scalp, arms, and/or legs in one grouping versus eyelids, nose, ears, and/or lips in the other grouping) the lengths of the repairs are reported separately, with the less complicated, secondary procedure appended with the 59 modifier. Note that an add-on code, 13122, was used to specify that up to an additional 5 cm of thigh closure length was done beyond the 7.5 cm length specified by the primary code, 13121. [pagebreak]

Example 3

A melanoma is excised from the left arm with a 1 cm margin producing a 3.5 cm maximum excision diameter that, after extensive undermining in order to facilitate skin edge apposition, is closed linearly in a layered fashion, resulting in a 9.5 cm length of repair. A separate atypical nevus is excised from a tight scalp and the 1.9 cm maximum excision diameter defect requires broad, extensive subgaleal undermining in order to reduce tension and allow for a layered linear repair measuring 6 cm in length. The CPT coding is as follows: 11604, excision malignant lesion, arm, 11422, excision benign lesion, scalp, and 13121 plus 13122x2 for the complex repairs.

Correct. Site and tumor type-specific (malignant and benign) excision codes are listed appropriately to differentiate between the melanoma and the atypical nevus excisions. The repairs are both complex, and although located in disparate sites, they fall under the same anatomical complex repair site grouping, that being scalp, arms, and/or legs. Consequently, the lengths of the two repairs are added to determine the proper CPT complex repair code, 13121 (2.5 to 7.5 cm length) and the add-on code 13122x2 indicates that two units of each additional 5 cm of closure length are billed to specify the sum total closure length of 15.5 cm.