Question:
Can modifier 91 be appended to every laboratory code that is reported more than one time on the same date of service?
Answer:
Although some third-party payers have suggested that modifier 91, Repeat Clinical Diagnostic Laboratory Test can be appended to every laboratory code that is reported more than one time on the same date of service, per the CPT® coding guidelines; this is not the appropriate method of reporting modifier 91. Modifier 91 indicates: In the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results.