A clinical diagnostic laboratory test is classified under which modifier if repeated?

When a clinical diagnostic laboratory test is repeated on the same day, it is classified under Modifier 91. This modifier is specifically used to indicate that a quantitative laboratory test has been repeated on the same day to obtain additional information regarding a patient’s condition. Modifier 91 clearly differentiates the repeated test from the initial test, ensuring accurate data collection and billing practices.

Using Modifier 91 helps healthcare providers maintain compliance with coding guidelines and ensures that payers understand the necessity of conducting the repeat test, which may be critical for patient management. This is essential for clear communication in clinical documentation and billing processes where the nature of the repeated test and its clinical importance need to be adequately justified for reimbursement purposes.

The other modifiers listed serve different purposes: Modifier 90 is used for tests performed by an outside laboratory, Modifier QW indicates a test that meets clinical laboratory Improvement Amendments (CLIA) waiver requirements, and Modifier 92 is used for outside laboratories that carry out tests using an established method. Each modifier has a specific application, but for repeated diagnostic tests, Modifier 91 is the appropriate choice.