Summary & Overview

CPT 88274: Interphase FISH, Analysis of 25–99 Cells

CPT code 88274 denotes an interphase fluorescence in situ hybridization (FISH) test in which an analyst evaluates 25 to 99 cells to detect chromosomal or genetic abnormalities in non-dividing cells. As a specialized molecular cytogenetic procedure, this code is relevant to clinical laboratories, hospital pathology departments, and clinicians managing hematologic malignancies, genetic disorders, and other conditions where targeted chromosomal assessment is indicated. Nationally, accurate coding affects laboratory billing, coverage determinations, and aggregation of utilization data for precision diagnostics.

Key payers considered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the clinical context for interphase FISH testing, coding interpretation, common sites of service, and the payer landscape. The publication also summarizes benchmark considerations for utilization and reimbursement patterns, highlights relevant policy and coverage themes affecting molecular cytogenetic testing, and clarifies the clinical scenarios in which counting 25–99 interphase cells is typically applied.

This resource is intended for laboratory billing specialists, coding professionals, hospital administrators, and clinicians who require a concise reference on CPT code 88274 and the operational and policy issues that influence its use.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareCPT 88274molecular cytogeneticsFISH testinglaboratory servicespathology billinginterphase analysisclinical diagnostics

Billing Code Overview

CPT code 88274 describes a molecular cytogenetic test performed by interphase in situ hybridization (FISH) with analysis of 25 to 99 cells. This assay evaluates genetic abnormalities in non-dividing (interphase) cells by using fluorescent probes to target specific DNA sequences and counting probe signals across multiple cells.

Service type: Molecular cytogenetic diagnostic testing (FISH)

Typical site of service: Clinical laboratory or hospital laboratory where cytogenetics and molecular pathology analyses are performed. Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A 56-year-old patient with unexplained cytopenias and an abnormal peripheral blood smear is referred for molecular cytogenetic testing. The clinician orders interphase fluorescence in situ hybridization (FISH) on a peripheral blood or bone marrow specimen to evaluate for common chromosomal abnormalities associated with hematologic malignancy (for example, translocations or copy number changes). The laboratory receives the specimen, accessioning staff log clinical history and ordering information, a cytogenetics technologist prepares interphase nuclei slides, applies validated FISH probes targeting specific loci, and performs hybridization and washes. An experienced molecular cytogenetics analyst examines and documents hybridization signals in 25 to 99 interphase cells, interprets results relative to laboratory-specific reference ranges and probe performance, generates a report describing positive, negative, or equivocal findings, and routes the report to the ordering hematologist/oncologist.

Typical site of service: hospital outpatient laboratory or independent clinical laboratory with molecular cytogenetics capability. Typical specimen sources: peripheral blood or bone marrow aspirate. Typical indications include evaluation of suspected leukemia, lymphoma, myelodysplastic syndrome, or monitoring of known chromosomal abnormalities.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When billing only the professional component (interpretation) of the test separate from the technical component.
`TC`	Technical component	When billing only the technical component (laboratory processing, hybridization, imaging) of the test.
`90`	Reference (outside) laboratory	When the test was performed by an outside reference laboratory and billed by the referring laboratory.
`91`	Repeat clinical diagnostic test	When the test is repeated on the same day to confirm prior results per laboratory policy.
`59`	Distinct procedural service	When a separate, distinct test or procedure is performed that is not normally billed together with this service.
`52`	Reduced services	When the service is partially reduced or not performed to full extent (e.g., fewer cells analyzed than typical but still reportable—use cautiously).
`53`	Discontinued procedure	When testing was started but discontinued due to specimen unsuitability or technical failure.
`22`	Increased procedural services	When the complexity or time required for analysis substantially exceeds typical expectations (rare for standardized FISH counts).
`95`	Synchronous telemedicine service rendered via real-time interactive audio and video	When remote real-time review or interpretation is performed via telepathology with synchronous interaction.
`91`	Repeat test (listed again for emphasis)	(See above)

Taxonomy Code	Specialty	Notes
207RC0000X	Clinical Cytogenetics Technologist / Technologist	Laboratory professionals who perform cytogenetic testing and analysis.
207L00000X	Clinical Laboratory Technologist	Professionals performing laboratory testing including molecular cytogenetics.
2080P0207X	Pathology	Pathologists who provide interpretation and oversight of cytogenetic testing.
207K00000X	Medical Technologist	Laboratory staff involved in specimen processing and FISH testing.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C91.0`	Acute lymphoblastic leukemia	Interphase FISH is used to detect translocations and gene copy changes relevant to diagnosis and risk stratification.
`C92.0`	Acute myeloblastic leukemia, not having achieved remission	Used to detect recurrent cytogenetic abnormalities (e.g., t(8;21), inv(16)) that inform diagnosis and prognosis.
`D46.9`	Myelodysplastic syndrome, unspecified	FISH can identify chromosomal deletions or monosomies associated with MDS.
`C83.9`	Non-Hodgkin lymphoma, unspecified	FISH may detect specific rearrangements (e.g., BCL2, BCL6) in lymphoid neoplasms.
`Z51.11`	Encounter for antineoplastic chemotherapy	Monitoring of known chromosomal markers by FISH can be part of treatment response assessment.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`88271`	Analysis of 1 to 24 cells using interphase FISH	Performed when fewer cells are analyzed; may be billed if only a smaller cell count is reported.
`88275`	Analysis of 100 or more cells using interphase FISH	Performed when the laboratory counts ≥100 interphase cells; represents higher cell-count analysis.
`88291`	Interpretation and report of cytogenetic analysis; summary and interpretation of FISH or other cytogenetic results	Often used for billing the interpretive summary report or additional comprehensive interpretation if separate from the technical analysis.
`88262`	Molecular cytogenetics; probe synthesis or validation (when applicable)	May be performed in workflows where probes are custom-labeled or validated in-house prior to testing.
`88184`	Cytopathology, FISH, probe-based testing on cell block or smear (per probe)	May be used in related specimen types or when FISH is performed on cytology material rather than standard interphase preparations.