What is the meaning of the -90 modifier?

The -90 modifier is used in the Current Procedural Terminology (CPT) coding system to indicate that a particular test or procedure was performed by an independent laboratory rather than by the physician or healthcare provider who is referring the patient for that service. This modifier is essential in situations where the provider needs to clarify that the analysis or test was conducted externally, often to ensure proper billing and reimbursement.

When a service is billed with the -90 modifier, it communicates that the results of the procedure are being reported back to the referring physician, who will then use that information in the management of the patient's care. This adds clarity to the billing process, especially in diagnostic services where interpretations from independent labs play a significant role in patient management.

The other options do not accurately represent the definition of the -90 modifier: for instance, a second opinion assessment would typically not require a modifier like -90; multiple modifiers could indeed be applied but would not be specifically signified by -90; and the same laboratory required does not reflect the intention of the modifier as it pertains to independent laboratory services. Thus, the choice of A effectively captures the unique role and application of the -90 modifier in clinical documentation and billing practices.