Ambulatory Surgical Center Payment Transparency Act of 2018 or ASC Payment Transparency Act of 2018 (Sec. 2) This bill requires the expert outside advisory panel that reviews the Medicare prospective payment system for hospital outpatient department services to include at least one ambulatory surgical center representative. (Sec. 3) The bill also requires the Centers for Medicare & Medicaid Services to specify the criteria used to exclude certain procedures from the list of covered surgical procedures that may be performed in an ambulatory surgical center under Medicare.