Hello,
You cannot bill for the whole global service when your dr is just reading. If a slide is sent out and prepped elsewhere, and all your dr is doing is reading when it comes in, you would use -26 modifier. The rest of the 1500 can be left as it would normally be billed.
(TC) - append when all that is done is prep for a slide
(26) - append when slide is prepped elsewhere and dr just reads results
(global, no mods) - ONLY when your office does both prep and read (i.e. in-house pathology)
Each of these will have a different price (and paid different-see Medicare fee schedule), generally the global is the highest, followed by -TC codes, then lowest would be -26 codes.
Hope this helps!
Mallory E, CPC