Summary & Overview

CPT 86609: Immunoassay for Antibodies to Specific Bacterium

CPT code 86609 identifies an immunoassay laboratory test performed to detect antibodies to a specific bacterium when no more specific CPT code applies. Nationally, serologic testing coded with 86609 is relevant for infectious disease diagnosis, public health surveillance, and clinical management when targeted assays are not available. Its use affects laboratory billing workflows, payer coverage determinations, and coding consistency across clinical laboratories.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context for antibody immunoassays, typical sites of service (clinical and hospital laboratories), and the aspects of billing and payer coverage that commonly affect claims for tests without a more specific code. The publication also summarizes common modifiers associated with laboratory services and highlights where input data is unavailable.

What readers will learn: benchmarks and coding practice implications for 86609, how major payers approach coverage and reimbursement for non-specific bacterial antibody immunoassays, and the clinical scenarios in which this test is typically ordered. Data not available in the input is noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare86609CPTimmunoassayserologylaboratoryinfectious-diseaseclinical-labmedical-billinglaboratory-coding

Billing Code Overview

CPT code 86609 describes an immunoassay performed by a laboratory analyst to detect antibodies to a specific bacterium not represented by a more specific CPT code. This service is a laboratory serologic test used to assess a patient’s immune response to a bacterial pathogen when no targeted code exists.

Service type: Immunoassay laboratory service
Typical site of service: Clinical laboratory or hospital laboratory setting

Clinical & Coding Specifications

Clinical Context

A 34-year-old patient presents to an outpatient clinic with a 2-week history of persistent fever, malaise, and a localized swollen lymph node after recent travel and possible animal exposure. The ordering clinician requests serologic testing to evaluate for antibodies to a less-common bacterial pathogen not represented by a more specific immunoassay code. A phlebotomy draw is performed in the clinic or ambulatory lab (typical site of service: outpatient/office-based laboratory). The blood specimen is sent to the clinical laboratory, where a medical technologist or lab analyst performs an immunoassay to detect patient antibodies directed against the specific bacterium. Results are reported to the ordering provider who interprets serology in the context of clinical findings and may order follow-up testing or treatment if serology is supportive of infection. Billing for the laboratory immunoassay uses 86609 to report an antibody immunoassay for a bacterial agent not categorized under a more specific CPT code; the facility or laboratory bills the technical component and the performing laboratory documents specimen handling, assay method, and result interpretation as required for laboratory billing and medical record documentation.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the physician/provider interpretation of the laboratory result separate from the technical component.

Taxonomy Code	Specialty	Notes
207Q00000X	Infectious Disease Specialist	Orders and interprets serologic testing for infectious agents.
207L00000X	Pathology/Clinical Pathologist	Interprets laboratory immunoassays and oversees laboratory testing.
363A00000X	Laboratory Director/Clinical Lab	Oversees clinical laboratory testing, quality, and reporting.
207K00000X	Allergy & Immunology	May order antibody testing when immune-mediated responses or atypical infections are suspected.

CPT Code	Description	Relationship to This Procedure
`36415`	Collection of venous blood by venipuncture	Often performed immediately prior to `86609` to obtain the blood specimen for the immunoassay.
`99000`	Handling and/or conveyance of specimen for transfer from physician office to laboratory	May be used by some payors when specimen handling/transport incurs an additional charge in the clinical workflow.
`81025`	Urinalysis, non-automated, with microscopy	May be performed in parallel when systemic bacterial or other infections are evaluated, depending on clinical presentation.
`86701`	Antibody; rubella (if specific viral serology required)	Represents a more specific immunoassay example — used to illustrate that `86609` is for bacteria not covered by more specific codes.

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