Can anyone tell me where I can get info on billing 93971-preop duplex can on the same day of 36478(vein obliteration) Horizon BCBS recently reqested an overpayment for the preop scan/vein mapping.93971 because it was done on the same day as a vein obliteration even though it was interpreted by a different physician.stating it was not medically necessay..thought on appeal!!!