CPT codes standardize the language medical professionals and insurers use to describe services and procedures performed on a patient. Encountering a five-digit code like 36475 on a medical bill can be confusing. This code represents endovenous ablation therapy, a common, minimally invasive treatment for a vein condition in the legs. Understanding the code requires knowing the procedure, the condition it treats, and its specific billing parameters.
The Endovenous Ablation Procedure
CPT code 36475 specifically describes endovenous ablation therapy, a technique that uses heat to seal off a diseased vein in the leg. The procedure is minimally invasive, acting as a modern alternative to traditional, more involved vein stripping surgery. A vascular specialist typically uses an ultrasound machine to guide the entire intervention.
The specialist first makes a small puncture, often near the knee or ankle, and inserts a thin, flexible catheter into the vein. Once positioned, the device delivers radiofrequency (RF) energy, which is a form of heat. This thermal energy causes the vein wall to collapse and close permanently.
The goal of closing the vein is to redirect the blood flow immediately to healthier veins nearby. The sealed vein then shrinks and is naturally absorbed by the body over time. Because only a tiny incision is needed, the procedure usually takes less than an hour and permits a rapid return to normal activities with minimal pain and scarring.
Treating Venous Insufficiency
The medical condition necessitating endovenous ablation is most often chronic venous insufficiency (CVI). CVI occurs when the one-way valves inside the leg veins become damaged. When these valves fail, blood struggles to flow back up toward the heart and instead pools in the lower extremities. This pooling increases pressure within the veins, leading to their enlargement and twisting, which are known as varicose veins.
Patients usually seek treatment for symptoms like leg pain, a heavy or tired feeling, nighttime cramping, and swelling in the ankles and lower legs. If left untreated, the elevated pressure can cause skin changes, such as discoloration, and in severe cases, the development of open sores called venous ulcers.
The procedure is not used for cosmetic purposes but is reserved for veins that are functionally compromised. Before the procedure can be performed and billed under CPT 36475, diagnostic testing must confirm the vein’s incompetence or reflux. This testing is typically a duplex ultrasound, establishing the medical necessity for the intervention. Conservative measures, such as wearing compression stockings and leg elevation, are often tried for a period of several months before thermal ablation is recommended.
Decoding the CPT Billing Rules
The full description for CPT code 36475 is “Endovenous ablation therapy of incompetent vein, extremity, inclusive of all imaging guidance and monitoring, percutaneous, radiofrequency; first vein treated.” The phrase “first vein treated” is a significant billing rule, meaning this code is used only for the initial, primary vein addressed in a single extremity during the session. If the practitioner treats a second, separate, incompetent vein in the same leg during the same session, they must use a different code, CPT 36476, which is an add-on code for subsequent veins.
The phrase “inclusive of all imaging guidance” explains that the fee covers the necessary ultrasound work used during the procedure. The provider cannot submit a separate charge for the ultrasound imaging used to guide the catheter and monitor the process. This bundling of services simplifies the billing and prevents patients from seeing multiple charges for the imaging component.
CPT 36475 also has an associated “global period,” which is often zero or ten days. This means the payment for the procedure includes any routine, related follow-up care, such as brief check-ups or wound care, within that defined period.