Question:
How should modifier -91 be reported under the National Correct Coding Initiative (NCCI)?
Answer:
Modifier -91 should be appended to laboratory procedure(s) or service(s) to indicate a repeat test or procedure on the same day. This modifier indicates to the Medicare contractors that the physician had to perform a repeat clinical diagnostic laboratory test that was distinct or separate from a lab panel or other lab services performed on the same day, and was performed to obtain medically necessary subsequent reportable test values. This modifier should not be used to report repeat laboratory testing due to laboratory errors, quality control, or confirmation of results.