When our pathology group sends a patient specimen out for expert consultation because we don't know what it is (very rare) we pay the consultant's bill.  Our feeling is that we are responsible for rendering a diagnosis on that specimen and there is no reason why the patient or the third party payor should have to pay for these additional consultation services.   After all, we are getting paid by the patient or the patient's insurance to make a diagnosis.   If we are asked to send out a specimen for a second opinion at the request of the treating physician or the patient, we send along the patient's insurance information for billing purposes.  In the case of special testing (e.g., EM, IP, special stains) not offered at the institution where the specimen is received, one can attempt to have the patient's insurance billed for these services, but the lab doing the testing may elect to do facility billing only.  I don't think you will find a consensus answer to this question.

RWC