Billing and Coding: MDS FISH

Use CPT 88271–88291 for ISH performed as ancillary to cytogenetic studies (e.g., MDS FISH) and use 88365–88377 only when ISH is performed by a pathologist as an adjunct to surgical/cytopathology—pathologists must not use 88365–88377 for cytogenetic ancillary testing. To report MDS FISH, submit the appropriate CPT with 1 unit of service and an ICD‑10‑CM code; a DEX Z‑Code™ is not required but if included must be entered adjacent to the CPT code in the claim comment/narrative (specified Part B fields such as Loop 2400/SV101‑7 or Item 19 for paper, and Part A fields such as SV202‑7 or UB‑04 Block 80).