CPT Code 37799: Unlisted Procedure, Vascular Surgery

What is an unlisted vascular surgery procedure?

CPT code 37799 is designated for unlisted procedures in vascular surgery when no specific code exists to describe the service performed. This unlisted procedure code serves as a placeholder that allows healthcare providers to report unique or rare vein procedures, such as those involving varicose veins, lower extremities, or an artery in the left leg, or treatments involving other arteries not typically addressed by standard codes.

Because these services fall outside standard CPT definitions, submitting code 37799 requires detailed documentation and proof of medical necessity to justify coverage and correct billing. The American Medical Association (AMA) maintains this code as part of its effort to provide flexibility for evolving treatment options and innovations in vascular surgery.

Procedures reported under 37799 must be performed in the operating room or clinical setting and clearly described by the physician to support accurate claims processing. Each submission undergoes review by Medicare Administrative Contractors (MACs) or other payers, who assess whether the service is covered, whether a modifier is needed, and whether the documentation provided meets criteria for reimbursement.

Proper use of 37799 helps ensure patients receive necessary treatment, even when standard codes do not apply.

Documentation requirements

A complete and compliant submission for CPT code 37799 should include:

• Detailed operative report outlining the entire procedure.
• Clinical indication and explanation of medical necessity, including diagnosis and symptoms.
• Step-by-step procedural description, clearly defining what was done.
• Devices, tools, and techniques used during the vascular surgery.
• Comparable CPT code used solely for valuation or reference purposes (not billed).
• Clear information provided and justification of why no existing or specific CPT code accurately represents the service performed.
• Supporting documentation and notice, such as relevant diagnostic imaging, pre-operative evaluation, and post-operative care instructions.

This level of detail is essential for Medicare, MACs, and private payers to determine coverage, appropriate reimbursement, and claim validity under the guidelines set by AMA and CMS.

Billing guidelines

• Use CPT code 37799 only when no existing CPT code (category I or III) accurately describes the vascular procedure performed.
• Manual payer review is required; submit complete documentation with the claim, including a detailed operative report and medical necessity.
• Suggest a comparable CPT code (e.g., 36475 for endovenous ablation) to help payers determine appropriate valuation and reimbursement.
• Do not report 37799 if a more specific CPT code exists, even if the service is slightly different or more complex.
• Check with the payer for preauthorization and submission requirements, as policies vary across Medicare, MACs, and private insurers for unlisted procedure codes.

Other relevant CPT codes

• 36475–36479 – Endovenous ablation codes
• 37765 – Ligation of perforator veins
• 37238 – Endovascular revascularization