In an initial visit with a health care provider, new patients routinely sign a disclosure form — often without giving it much thought. This document allows for (among other things) doctors to share your medical records, including diagnosis and procedures performed, with your health insurance carrier for reimbursement.
Should you decide not to sign or disclose your health information, technically speaking, medical records cannot be shared with a third party, including your insurance carrier. At that point, any and all expenses incurred become your responsibility.