According to the CPT manual, modifier 91 should not be used when tests are what?

Modifier 91 is specifically designed for use with laboratory tests when the same test is performed on the same patient on the same day to confirm initial results. The use of this modifier indicates that the test was repeated for the purpose of verifying the accuracy of the initial test result due to certain circumstances, such as a positive or unexpected finding.

When tests are rerun simply to confirm initial results, it directly aligns with the application of modifier 91, as it signifies that verification of results is what distinguishes this instance of testing. Therefore, its application is warranted in situations where there is a clear need to ensure that the findings from the first test are accurate and reliable.

In contrast, the other options reflect scenarios in which modifier 91 would not be appropriate. For instance, running multiple tests for verification typically refers to separate tests that might be conducted to verify different results or to corroborate findings, not merely repeating the exact same test for the same patient. Administering tests to different patients does not necessitate modifier 91 because it is not within its scope; the modifier applies when the same test is being conducted on a single patient. Lastly, tests performed under clinical trial settings usually follow specific protocols and may not require modifier 91, as the context of the