CPT 88273 FISH (10–30 Cells) Reimbursement

CPT code 88273 represents a targeted molecular cytogenetic test performed by chromosomal in situ hybridization (commonly FISH) that analyzes 10–30 cells to detect chromosomal abnormalities such as microdeletions or segmental loss. This test is clinically important for prenatal diagnosis, hematology-oncology workups, and tissue-based genetic evaluations, providing rapid, cell-specific information that complements karyotyping and other genomic assays. Nationally, utilization of FISH-based cytogenetic testing affects laboratory workflows, payer coverage policy, and diagnostic pathways for genetic conditions.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context, typical settings where the test is performed, and the operational implications for laboratories and ordering clinicians. The publication also presents benchmark information, relevant coding and billing considerations, and recent policy or coverage updates where available. Data not available in the input will be noted in the detailed sections. This summary equips payers, laboratory managers, and clinicians with a clear understanding of what CPT code 88273 captures and why it matters in diagnostic genetics.

Billing Code Overview

CPT code 88273 describes a molecular cytogenetic analysis using chromosomal in situ hybridization to examine 10 to 30 cells, commonly applied to samples such as amniotic fluid, peripheral blood, or tissue. The procedure uses methods such as fluorescence in situ hybridization (FISH) to detect targeted genetic abnormalities, including microdeletions or loss of chromosomal segments, at the single-cell level.

Service type: Molecular cytogenetic diagnostic test (FISH-based analysis)

Typical site of service: Clinical laboratory or hospital outpatient/diagnostic laboratory settings, with specimens obtained from amniotic fluid, blood, or tissue depending on the clinical indication.

Clinical Context

A 32-year-old pregnant patient at 18 weeks' gestation is referred to prenatal genetics after abnormal ultrasound findings suggestive of a microdeletion syndrome. Amniocentesis is performed to obtain amniotic fluid. The laboratory performs a molecular cytogenetic test using chromosomal in situ hybridization, typically fluorescence in situ hybridization (FISH), analyzing 10–30 interphase cells to detect targeted chromosomal deletions, duplications, or aneuploidies. Results are reported to the maternal-fetal medicine specialist and genetic counselor who review findings with the patient and document implications for fetal prognosis and available options.

Coding Specifications

Modifier	Description	When to Use
`11`	Duplicate of primary service (usually not used)	Rarely applicable; only if billing rules require indicating a standard service as distinct from multiple same-day entries.
`22`	Increased procedural services	Use when the test required substantially greater effort or complexity (e.g., extensive probe troubleshooting or multiple probe sets beyond typical scope) and documentation supports increased work.

Taxonomy Code	Specialty	Notes
207R00000X	Pathology	Clinical cytogenetics and molecular pathology laboratories perform FISH testing and interpretation.
2080P0207X	Obstetrics & Gynecology	Maternal-fetal medicine specialists order and coordinate prenatal diagnostic testing.
2083P0300X	Clinical Genetics	Geneticists and genetic counselors interpret results and counsel patients.
261QM0800X	Clinical Laboratory	Clinical laboratory directors and laboratory medicine specialists oversee testing quality and reporting.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Q93.4`	Monosomy, not elsewhere classified	FISH can detect partial or whole-chromosome monosomies in fetal cells when specific probes target suspected missing regions.
`Q93.5`	Trisomy, not elsewhere classified	Targeted FISH panels are commonly used to evaluate suspected trisomies (for example chromosomes 13, 18, 21).
`Q87.1`	Congenital malformation syndromes predominantly affecting facial appearance	Suspicion of a microdeletion syndrome associated with characteristic facial features can prompt locus-specific FISH testing.
`Q89.3`	Microdeletion syndromes, chromosomal	Direct indication for FISH testing when ultrasound or family history suggests a microdeletion.
`Z34.80`	Encounter for supervision of normal pregnancy, unspecified trimester	Routine prenatal care context where abnormal screening findings may lead to diagnostic FISH testing (used for encounter documentation when applicable).

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`88271`	Chromosomal in situ hybridization; probe(s) for single probe/target (eg, enumeration of chromosome-specific centromere or locus-specific probe)	Often billed for single-probe FISH assays such as targeted aneuploidy or locus-specific deletion testing that analyze fewer cells or simpler probe sets.
`88272`	Chromosomal in situ hybridization; probe(s) for two probes/targets	Used when a dual-probe FISH panel is performed (e.g., two loci or dual-color probes) prior to or instead of the broader 10–30 cell analysis.
`88274`	Chromosomal in situ hybridization; probe(s) for panels, multiple probes (eg, subtelomeric or multiplex probe sets)	Applied for larger probe panels or multiplex FISH that examine multiple loci, complementary to `88273` when more extensive cell counts or probe sets are used.
`88275`	Interpretation and report only; chromosomal in situ hybridization, any method	Billed when the interpreting pathologist/clinical cytogeneticist provides only the professional interpretation and report while a reference lab performed the technical testing.
`89049`	Amniotic fluid analysis; fetal cells	Related specimen procurement and processing codes for amniotic fluid specimens that supply cells for the FISH analysis; appears earlier in workflow.

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Summary & Overview

CPT 88273: Molecular Cytogenetic Analysis by FISH, 10–30 Cells