Related or unrelated? Distinction is important for correct modifier selection

Knowing the distinction between "related" and "unrelated" services is vital to proper interpretation of CPT language and intent. These definitions are important for services provided in the global period. These services need to be reported with one of these modifiers: –78, –79, or –24.


These definitions are especially important for services provided in the global period. Medicare will pay for services provided in the global period, but in general, these services need to be reported with a modifier, as discussed below. Correct choice of the modifier is important because the length of the global period and the payment rate will depend on the modifier chosen.

A review of the "global surgical package" is worthwhile. The global surgical package is the basket of services that is considered to be part and parcel of a surgical service for purposes of reporting and reimbursement. These comments are based on Medicare's view.

Certain office visits during the global period are also payable. Visits that don't represent routine postoperative care are not part of the global package. Treatment for the underlying condition is specifically also excluded from the global package.

The relevant CPT language includes the words "related" and "unrelated." "Related" in this context means that the service is required as a result of the base procedure. Another way of viewing this is by asking, "If the procedure had not been performed, would this situation have had a reasonable chance of developing?" If the answer is yes, then the situation is considered "unrelated" to the base procedure. If the answer is no, then the situation is "related."

Modifier –78

Modifier –78 is defined as "return to the operating room for a related procedure during the postoperative period." Applying the standard above, it is clear that this modifier is appropriate for reporting complications of the base procedure requiring a return trip to the operating room.

Treatment of a complication of this sort is reimbursed at what is known as the "intraoperative" rate. The implication is that the necessary preoperative work and postoperative work for the second operation have already been essentially captured in the payment for the first operation. Payment at the full rate (preoperative plus intraoperative plus postoperative) is not provided because it is viewed as double payment for the preoperative and postoperative components.

Because the postoperative work from the first operation is applied to the second operation, it makes sense that another global period does not start following the second procedure.

The intraoperative percentages for all the CPT codes can be found on the Medicare Web site, They are located in the Physician Fee Schedule Search, found in the Physician Center, under "Policy and Pricing Information." (To reach this point, you need first need to select "Pricing Information.") The standard intraoperative percentage for ophthalmology codes is 70%, but the intraoperative percentage is 80% for several codes.

If the second procedure is an "unlisted procedure" (i.e., a code ending in –99), there will be no defined intraoperative percentage. In these cases, payment may be up to 50% of the payment level for the first procedure.

Modifier –79

Modifier –79 is defined as "unrelated procedure or service by the same physician during the postoperative period." This modifier is used when the second surgery is not simply a consequence of the first surgery.