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    v1.0.28
    OpenPayerBilling CodesQualitative or Semiquantitative ImmunoassaysCPT cpt-86171-complement-fixation-antigen-detection
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    CPT 86171: Complement Fixation Antigen Detection

    CPT code 86171 describes a technical laboratory procedure using complement fixation methods to detect the presence of specific antigens (for example, influenza virus) in a clinical specimen; this service is a laboratory diagnostic test typically performed in a clinical or hospital laboratory setting and billed as a technical component for antigen detection by complement fixation.

    For related coverage guidance, see recent payer policy updates: Diagnosis of Idiopathic Environmental Intolerance, Allergen Testing, Allergen Testing.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an adult presenting to an outpatient clinic or urgent care during influenza season with acute onset fever, cough, myalgias, and respiratory symptoms. A clinician collects a nasopharyngeal or throat specimen and sends it to the clinical laboratory for antigen detection. In the laboratory, a medical technologist or laboratory analyst performs a complement fixation–based serologic or antigen detection assay to identify the presence of specific viral antigens such as influenza virus. Results are reported back to the ordering clinician to guide antiviral therapy decisions, infection control, and public health reporting. Typical workflow steps include specimen receipt, accessioning, preparation, performance of the complement fixation assay, quality control, result interpretation, and electronic reporting of final results into the chart or laboratory information system.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    87205Infectious agent antigen detection by immunoassay technique, single step method (e.g., enzyme immunoassay)Alternative rapid antigen detection methods that may be ordered instead of complement fixation for influenza antigen detection
    87502Infectious agent detection by nucleic acid (DNA or RNA); influenza virus, amplified probe techniqueMolecular testing commonly performed alongside or as confirmatory testing when increased sensitivity is needed
    87210Infectious agent detection by immunofluorescent technique, direct agent detectionAlternate laboratory method for viral antigen detection using immunofluorescence
    86038Antibody; infectious agent antibody, each qualitative or semiquantitative testSerologic antibody testing that may be ordered in addition to complement fixation methods for immune response assessment
    99000Handling and/or conveyance of specimen for transfer from site of collection to laboratoryAdministrative or logistical service often billed when specimens are transported to an external laboratory

    Related Modifiers

    8 rows

    ModifierDescriptionWhen to Use
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…
    91Modifier 91 — “Repeat Clinical Diagnostic Laboratory Test” — is appended when the exact same CPT laboratory test is performed more than once for the same patient on the same day because serial,…- Use modifier 91 when the exact same CPT laboratory test is performed more than once on the same patient on the same date because serial or repeated testing is medically necessary to monitor…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…
    78CPT modifier -78 indicates an unplanned, related return to the operating or procedure room by the same provider during the global postoperative period. It is appended when treatment for a…- Use modifier -78 when an unplanned, related complication during the original procedure’s global postoperative period requires the patient to return to a formal operating or procedure room and the…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207R00000XInternal Medicine PhysicianA physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults…
    363L00000XNurse Practitioner(1) A registered nurse provider with a graduate degree in nursing prepared for advanced practice involving independent and interdependent decision mak…
    175F00000XNaturopathDiagnoses, treats, and cares for patients, using system of practice that bases treatment of physiological functions and abnormal conditions on natural…
    2086S0102XSurgical Critical Care PhysicianA surgeon with expertise in the management of the critically ill and postoperative patient, particularly the trauma victim, who specializes in critica…
    251X00000XSupports Brokerage AgencyA provider of service/function that assists participating individuals to make informed decisions about what will work best for them is consistent with…
    363LP0808XPsychiatric/Mental Health Nurse PractitionerPhysician Assistants & Advanced Practice Nursing Providers · Nurse Practitioner
    101YM0800XMental Health CounselorBehavioral Health & Social Service Providers · Counselor
    2278P1005XPulmonary Rehabilitation Certified Respiratory TherapistThe respiratory therapist can assist the chronic pulmonary patient in returning to an optimal role in society by providing an effective program. It i…

    Related ICD-10-CM Codes

    26 rows

    ICD-10-CM CodeDescription
    A49.9Bacterial infection, unspecified
    B34.0Adenovirus infection, unspecified
    B34.2Coronavirus infection, unspecified
    B34.9Viral infection, unspecified
    B97.21SARS-associated coronavirus as the cause of diseases classified elsewhere
    B97.29Other coronavirus as the cause of diseases classified elsewhere
    J00Acute nasopharyngitis [common cold]
    J02.9Acute pharyngitis, unspecified
    J03.90Acute tonsillitis, unspecified
    J06.9Acute upper respiratory infection, unspecified

    Showing 1–10 of 26

    Related Payer Policy Updates

    Specialty: Allergy/Clinical Immunology1 / 3

    9 rows

    PolicyPayerEffective Date
    Diagnosis of Idiopathic Environmental IntoleranceOscar Health2026-10-01
    Allergen Testingblue cross blue shield - louisiana2026-09-15
    Allergen TestingBlue Cross Blue Shield - New Mexico2026-09-04
    Hereditary Angioedema - EkterlyCigna2026-08-15
    Omalizumab products (Xolair, Omlyclo) coveragePremera Bluecross2026-08-01
    Omalizumab Products (Xolair, Omlyclo) coveragePremera Bluecross2026-08-01
    Omalizumab ProductsPremera Bluecross2026-08-01
    Allergy Testinguniverahealthcare2026-07-16
    Omalizumab (Xolair) and related biologics coverageMass General Brigham Health Plan2026-07-01

    Related Codes

    86803-QUALITATIVE-OR-SEMIQUANTITATIVE-IMMUNOASSAYS-HEPATITIS-C

    CPT 86803: Hepatitis C Antibody Immunoassay in Serum

    CPT-86000-FEBRILE-AGGLUTININS-SEROLOGIC-TEST

    CPT 86000: Febrile Agglutinins (Serologic Agglutination) Test

    CPT-86001-ALLERGEN-SPECIFIC-IGG-LABORATORY-TEST

    CPT 86001: Allergen-Specific IgG Assay, Technical Component

    CPT-86003-ALLERGEN-SPECIFIC-IGE-ASSAY-TECHNICAL

    CPT 86003: Allergen‑Specific IgE Assay Using Crude Allergen Extract

    CPT-86005-MULTI-ALLERGEN-IGE-SCREENING-QUALITATIVE

    CPT 86005: Multi-Allergen Allergen-Specific IgE Screening

    CPT-86008-ALLERGEN-COMPONENT-SPECIFIC-IGE-ASSAY

    CPT 86008: Allergen Component–Specific IgE Assay

    CPT-86015-ANTI-ACTIN-SMOOTH-MUSCLE-ANTIBODY-ASMA

    CPT 86015: Actin (Smooth Muscle) Antibody (ASMA) Immunoassay

    CPT-86021-LEUKOCYTE-ANTIBODY-IDENTIFICATION-LAB-TECHNICAL

    CPT 86021: Leukocyte Antibody Identification Laboratory Test

    CPT-86022-PLATELET-ANTIBODY-IDENTIFICATION-TECHNICAL-TEST

    CPT 86022: Platelet Antibody Detection and Identification

    CPT-86023-PLATELET-ASSOCIATED-IMMUNOGLOBULIN-DETECTION

    CPT 86023: Platelet-Associated Immunoglobulin Assay

    Showing 1–10 of 199

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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