There’s No CPT Code for My Service!

How to use unlisted and category III CPT codes.

By Katharine L. Krol, MD, FSIR, FACR

The ability to be paid can potentially affect acceptance and implementation of new technology and medical advancements. If there is not a specific CPT (current procedural terminology) code that correctly describes a new technology or procedure, it can be difficult or impossible to be paid for the procedure. The CPT process lags behind technology for multiple reasons.


Category I CPT codes describe specific, established services for patients. These codes go through the valuation process of the RUC (Relative Value Update Committee) of the AMA (American Medical Association) and have assigned values. Specific requirements for new category I CPT codes include:

1. FDA approval, if a device or drug is involved;
2. The procedure, including its safety and efficacy, must be established in peer-reviewed medical literature, with at least a portion of the data reported on United States populations, and at least a portion of the data reported in United States medical literature;
3. It is a distinct service that is not described by existing CPT code(s);
4. It is performed by a significant number of practitioners;
5. It is performed in more than one geographical area.

These requirements serve multiple functions. They work to ensure that the new service is established and has been performed widely enough to allow accurate definition of the service. In many new services or technologies, initial work frequently leads to modification of the service, and CPT codes are typically assigned once the procedure has undergone initial testing and modification so that the definition/nomenclature assigned to the service will still accurately define the service once the code is published for use several months later. FDA approval is required, which also adds validity to the safety and efficacy of the procedure, making it more likely that the service is established and less likely to be in the early, evolutionary phase of development. Valuation requires that enough practitioners have experience providing the new service to allow a statistically valid RUC survey.

The CPT process takes several months. Once the previously mentioned requirements are met, an application for a new code or codes must be submitted to the CPT committee, which meets three times per year. The committee reviews numerous applications for each meeting, and each application is reviewed by each committee member. Once a new code has passed, it moves to the RUC committee, which determines the valuations for the physician’s work and practice expense using expert input from specialty societies. The code is then reviewed by CMS, which has ultimate determination of the assigned value that is published in the Final Rule in the fourth quarter of each calendar year. The code then becomes available for use January 1 of the following year. Depending on when the code application is submitted in relation to the CPT annual cycle of meetings and when the code is passed by the CPT committee, the time from application to publication of a new category I code can be anywhere from 15 to 26 months.

This process, while allowing for constancy and validity in the CPT code set, can create a gap between clinical acceptance/patient demand of new services and a clear way to report and be paid for the services. This gap can slow diffusion of new technology into clinical practice. However, there are options to help bridge the gap. Category III codes and “unlisted procedure” CPT codes can be used to report services for which there is not an accurate category I CPT code.


Category III codes are used to describe emerging technology. These codes may be created when new services are under investigation, have not yet received FDA approval for a new drug or device involved with the service, are not yet widely practiced, or do not meet the literature requirements for category I codes. These codes define specific services but do not go through the RUC process and are not assigned values. If the service evolves and the requirements for a category I code are met, a new application for a category I code is required. The new code may keep the same definition as the category III code, but that is not a requirement, and sometimes the category I code will be structured differently than the category III code that preceded it. Unlike some older category III codes, which were designed as component codes and could be reported with category I codes so that only the new portion of the procedure was described by category III codes, the trend in recent years has been to describe the entire procedure in the category III code.

If a bill is submitted with a category III code, additional work will likely be required in order to be paid. Because these codes have no assigned value, payers are likely to not pay for the procedure because they do not know what service the patient has received or how to value that service. Discussion with the carrier before doing the procedure may be very helpful, allowing the payer to understand what service is being considered, why it will benefit their patient, and an estimation of the charge for the procedure. The submitted bill should include an explanatory letter/documentation. This documentation should include a description of the procedure, its benefit to the patient, why this new service was chosen over existing procedures, the work involved, and an estimated value of the work. It is often helpful to identify services with similar levels of work that the carrier can compare to the new procedure. The existing valuations for the comparison procedures may be used as potential crosswalks to help determine the value of the new procedure. Template letters containing much of this information are sometimes created by national societies and then made available for members to personalize and use to facilitate the billing process.


Within CPT, there are multiple codes that specify “unlisted procedure,” for instance:

37799—Unlisted procedure, vascular surgery

36299—Unlisted procedure, vascular injection

76999—Unlisted ultrasound procedure (eg, diagnostic, interventional)

Like category III codes, the unlisted procedure codes do not have assigned values. They can be used to report services that do not have category I or category III codes available, but will likely require additional work similar to that described for category III codes to be recognized or paid by carriers.


Typically, if a category III code is available and describes the service provided, the category III code should be reported. However, if a payer has directed otherwise, the payer’s direction should take precedence.

There are benefits to using category III codes, including the ability to track the new procedure. The CPT code application requests data on how often the procedure is done and how widely it is done. This information cannot be determined when unlisted procedure codes are reported, because numerous services may be reported with the same unlisted code. When enrolling patients in clinical trials, use of category III codes may be helpful to carriers, allowing them to set values for the trial and to track patients undergoing the trial procedures.

The timeline for creating category III codes is shorter than for category I codes because they do not go through the valuation process, and the category III codes are activated in January and July. However, there still may be a gap between when the service is provided and when a category III code is available, and in these instances, unlisted codes may be the only option available.


There are existing tools available to help providers report services that are new and not yet defined by a category I CPT code. While many people think that category III and unlisted procedures codes will not be paid, there have been multiple successes in using these codes to help advance new technology to patient care. Use of some of the suggestions in this article may improve the ability to support innovation that can lead to better (and sometimes less expensive) care for patients.

Katharine L. Krol, MD, FSIR, FACR, is an interventional radiologist and has recently retired from active clinical practice. She has disclosed that she has no financial interests that pertain to this topic. Dr. Krol may be reached at (317) 595-9413.

CPT copyright 2013 American Medical Association. All rights reserved. 



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