Neurosurgery Coding Alert

Question: I-m familiar with CCI edits, but what does the term "mutually exclusive" mean when applied to a code pair? Does "mutually exclusive" have an effect on how I treat the edits?

Arizona Subscriber

Answer: Mutually exclusive procedures are those procedures that "cannot reasonably be performed during the same operative session," according to national Correct Coding Initiative (CCI) guidelines. These procedures are designated mutually exclusive based either on the CPT definition or on the medical impossibility/improbability that the procedures could be performed at the same session.

An instance of mutually exclusive procedures would occur when there are two methods of repair for the same organ. Reasonably speaking, you would choose and report only one repair method, not both.

As a specific example, 61312 (Craniectomy or craniotomy for evacuation of hematoma, supratentorial; extradural or subdural), which describes treating a blood clot on the brain's surface, is mutually exclusive with 61313 (... intracerebral), a treatment for a blood clot beneath the brain's surface. You wouldn't remove a clot beneath the surface without removing one on the surface.

From a practical standpoint, you wouldn't treat mutually exclusive code pairs any differently than CCI "column 1/column 2" edits. Under normal circumstances, you would not report the codes together. In some limited circumstances, however, such as if procedures occur during different sessions -- and if the code pair edit has a "1" modifier indicator -- you may append a modifier, such as modifier 59 (Distinct procedural service), to override the edit.

For example, CCI defines 20660 (Application of cranial tongs, caliper or stereotactic frame, including removal [separate procedure]) as mutually exclusive of 61793 (Stereotactic radiosurgery [particle beam, gamma ray or linear accelerator], one or more sessions). This edit has a modifier indicator of "1," however, which allows for the possibility of separate billing with an appropriate modifier if the situation warrants.

When the surgeon performs radiosurgery in the morning, for instance, but for other reasons must apply a halo at a separate session later in the day, you may report 61793 for the initial service and 20660-59 for the halo placement on the same date of service.