If you are reporting unlisted codes, modifiers are not appended to unlisted codes. Modifiers are used to report or indicate a procedure performed has been altered but not changed in its definition or code. You can't alter an unlisted code which has no definition. Also regarding modifier 51 - it's added to identify multiple procedures kind of like saying - hey payer apply the multiple procedure reduction to this (lesser RVU) code and not the primary. Some payers don't even want 51 because the system ranks by RVU. That said - CMS and CPT conflict in some cases as there are some instances where modifiers are required for CMS and/or other payers per guidelines.
Note: Medicare doesn’t recommend reporting Modifier 51 on your claim; our processing system will append the modifier to the correct procedure code as appropriate. appended any longer.
MODIFIERS AND UNLISTED CODES As previously discussed, a modifier is the method used by the reporting physician to indicate or flag a service or procedure code regarding special circumstances affecting that service without changing the service or procedure description itself. It should be noted that when a procedure is performed that cannot be assigned to a specific CPT code and the provider must assign an unlisted code, the CPT code book conflicts with instructions from CMS regarding the use of modifiers with unlisted codes. The CPT book indicates that a modifier should not be appended to unlisted codes since there is no need to alter the definition of an unlisted code because the code does not describe any particular service. However, CMS proposes that the modifier is not altering the meaning of the code, but rather providing additional information. For example, IOM Pub 100-04, chapter 12, section 30.6.10, states: “Unlisted evaluation and management service (code 99499) shall only be reported for consultation services when an E/M service that could be described by codes 99251 or 99252 is furnished, and there is no other specific E/M code payable by Medicare that describes that service.” CMS further states that “the principal physician of record shall append modifier ‘-AI’ (Principal Physician of Record), in addition to the E/M code.” Other valid modifiers that may be required by Medicare that depend on the circumstances include AK, AR, CR, GC, GF, GJ, GR, GY, GZ, Q5, and Q6. Circumstances in which modifiers may be assigned with unlisted CPT codes are also found in the Medicare physician fee schedule (MPFS). The MPFS includes columns for multiple procedures, bilateral surgeries, assistant surgeons, co-surgeons, and surgical teams. Over 150 unlisted CPT codes have at least one modifier assigned in the MPFS. In addition, modifiers TC (Technical Component) and 26 (Professional Component) are assigned to radiology, laboratory, and medicine unlisted codes (for example, 76499, 76999, 88199, 91299, and 92499). In addition to modifiers 26 and TC, MPFS includes guidance on the following modifiers: 50, 51, 62, 66, 80, 81, 82, and AS.
Can I use modifiers with unlisted codes? It is not appropriate to append any modifier to an unlisted code because modifiers are used to indicate that a service or procedure has been altered by some specific circumstance, but not changed in its definition or code. Unlisted codes do not describe a specific service; therefore, it is not necessary to utilize modifiers.
CPT Assistant August 2002
Regarding unlisted codes. If there is no appropriate CPT to report what was done you would report the unlisted code. You would use a "like" code to compare from a reimbursement (RVU) perspective. The provider can usually help with a code to compare it to.
This is a good article regarding unlisted codes. It's not "official" from a guideline perspective but explains well: