88366 Insitu hybridization (fish)

What 88366 is

CMS fee schedule short descriptor: Insitu hybridization (fish).

Full CPT long descriptions are licensed by the American Medical Association and are not published on this site; the short descriptor above is the one CMS prints in its own fee schedule file. See About CPT.

Medicare payment for 88366 (CY2026)

National rates: total RVUs x the CY2026 conversion factor of 33.4009 (non-QP), before geographic adjustment. Actual Medicare payment is 80% of the rate shown after the deductible; the patient or secondary payer owes the 20% coinsurance.

Status: Active - payable under the Physician Fee Schedule. Global period: Global concept does not apply.

Medically Unlikely Edit (MUE)

Medicare caps 88366 at 2 units per date of service for practitioner claims (MAI 3 - date of service edit (clinical): units above the MUE may pay with documentation on appeal), rationale: Clinical: Data. Units above the cap are denied unless the edit's adjudication rules allow an appeal with documentation.

Billed with 88366? These codes are bundled into it

88366 is a Column 1 code in 15 active NCCI PTP edits. When one of these Column 2 codes is reported on the same date of service, it is denied as bundled - unless the edit's modifier indicator is 1 and documentation supports a distinct service with an NCCI-associated modifier.

88366 is bundled into these codes

88366 appears as a Column 2 code in 475 active edits. Reported with one of these Column 1 codes on the same date of service, 88366 is the code that denies.

Data: CMS CY2026 Physician Fee Schedule RVU file (October release, RVU26D) and Medicare NCCI PTP practitioner edits v32.3 (2026 Q4). Verify against the official files before billing or contracting decisions.