Question: If our pulmonary function test lab performs spirometry in the supine and upright positions, can we bill 94010 twice? If so, should we use a modifier on the second 94010? Tennessee Subscriber Answer: Medicare has not established frequency rates for billing spirometry. To report spirometry performed in both the supine and upright positions, you must indicate medical necessity in your clinical documentation. For example, the patient presents with a muscular abnormality or other condition that requires multiple spirometries. If this is the case, you should code the comorbid conditions and include this information in the pulmonologist's report. You should append modifier -76 (Repeat procedure by same physician) to the subsequent spirometries to indicate that the procedure was repeated after the initial service.