What modifier represents an unusual non-overlapping service that is not a usual component of the main service?

The modifier that represents an unusual non-overlapping service that is not a usual component of the main service is XU. This modifier is part of the 2016 update to the modifiers used in outpatient coding and is specifically designed to indicate that a service or procedure has been performed in a unique or special circumstance.

Using XU helps clarify that the service provided is not typically associated with the primary service and that it is performed under distinct conditions that justify the additional coding. This is particularly important in ensuring that claims are processed correctly, as it helps coders distinguish between regular and atypical scenarios where additional services are offered.

Modifiers XE, XS, and XP also provide additional context for bundled services but are used in different scenarios. For example, XE is used to indicate a service that is separate but related, while XS denotes a service that is a separate structure. XP is used for a service that is distinct in its location. Each modifier serves a unique function, but for services that are unusual and non-overlapping, XU is the correct choice.