What modifier is used to indicate that an outside laboratory performed testing?

The modifier that indicates an outside laboratory performed testing is -90. This modifier is specifically used for reporting laboratory services that were developed or performed by an independent laboratory or outside laboratory rather than the primary provider. When a practice or healthcare provider sends specimens away to an external lab for analysis, the -90 modifier must be included to clarify that the service was not performed in-house. This is important for billing purposes, as it helps ensure that the reimbursement process acknowledges the role of the outside laboratory in providing the service.

Understanding the use of modifiers like -90 is essential for accurate coding and billing, as it provides necessary details about the services rendered, which can affect reimbursement and compliance with regulations.