A physician at an internal medicine practice performs percutaneous allergy tests and faxes prescriptions for allergy serum, or antigen, to a vendor organization that prepares it. The patient then receives injections at our office. The initial set of injections usually consists of five vials of multiple antigens of different dilution intervals. The vendor that prepares the serum bills our practice, and we charge the patient. How do we bill Medicare for that so the patient’s serum can get reimbursed? Code 95144 is used for preparing the serum, but it’s unclear how to do it in that scenario because the vendor, which does not have its own billing services, does it on our behalf. How can we bill this service in a way that reduces the patient cost?