Pathology/Lab Coding Alert

Question: What modifier should we use when multiples of the same CPT code are billed for a Medicare outpatient on the same day? I understand when the -91 modifier would apply, but the business office has apparently run into difficulty with our fiscal intermediary with CPT code 82784 (gammaglobulin, IgA, IgD, IgG, IgM, each), when, for example, IgA, IgG and IgM are being determined.

Claudia Andrews
Providence Portland Medical Center, Portland, Ore.

Answer: Given appropriate documentation for the medical necessity of testing for the various substances, using modifier -91 (repeat clinical diagnostic laboratory test) would be appropriate in the example you presented. Although each analysis may involve a different substance, the same laboratory test procedure, represented by the same CPT code, is run multiple times. When multiple units of a laboratory test (one CPT code) are performed for the same outpatient on the same day due to the need for multiple results in the course of treatment, modifier -91 should be used.

Note that modifier -91 should not be used if the test is repeated to confirm initial results, because of testing problems related to specimens or equipment, or for any other reason when a normal, one-time reportable result is all that is needed for appropriate patient treatment. Also, note that modifier -91 may be used only for laboratory tests paid under the clinical diagnostic laboratory fee schedule.