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    v1.0.28
    OpenPayerBilling CodesHematology and Coagulation ProceduresCPT cpt-85597-phospholipid-dependent-coagulation-assay
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    CPT 85597: Platelet Phospholipid-Dependent Clotting Time

    CPT code 85597 describes a laboratory assay that measures clotting time after adding platelet membrane phospholipids to a patient blood specimen; this is a specialized coagulation test used to evaluate phospholipid-dependent clotting function, typically performed as a clinical laboratory service in an inpatient or outpatient hospital laboratory or reference laboratory setting.

    For related coverage guidance, see recent payer policy updates: Epithelial Cell Cytology in Breast Cancer Risk Assessment, Chemotherapy Observation or Inpatient Hospitalization (for New Mexico Only), Antibody-Drug Conjugates.

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    Clinical & Coding Specifications

    Clinical Context

    A patient presents for laboratory evaluation of a suspected coagulation disorder after a history of unexplained bleeding and/or a prolongation of routine coagulation assays. Typical patients include adults or children with abnormal bleeding, recurrent thrombosis on anticoagulation, suspected antiphospholipid syndrome, or evaluation of lupus anticoagulant when screening tests (e.g., prolonged activated partial thromboplastin time) are abnormal. The clinical workflow begins with a clinician order for coagulation studies; a phlebotomy technician draws a citrated plasma specimen and the specimen is labeled and sent to the laboratory. The laboratory technologist performs screening tests (PT/INR, aPTT). If an abnormal aPTT or clinical suspicion of an antiphospholipid antibody exists, the lab performs the platelet neutralization procedure to assess phospholipid-dependent clotting by adding platelet-derived phospholipids to the patient specimen and measuring correction of clotting time. Results are reported to the ordering clinician with interpretation (e.g., correction suggests a phospholipid-dependent inhibitor) and incorporated into clinical decision-making for anticoagulation management, further serologic testing, or hematology referral. Typical site of service is an outpatient or hospital clinical laboratory with testing performed by credentialed medical laboratory scientists.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    85730Thrombin time (TT); quantitativePerformed when evaluating fibrinogen function or presence of thrombin inhibitors, often ordered alongside phospholipid-dependent assays.
    85610Prothrombin time, partial thromboplastin time and test for mixing studiesRoutine screening coagulation assays that frequently precede or accompany platelet neutralization/phospholipid assays.
    85613Thromboplastin time, partial thromboplastin time, and mixing study interpretationUsed when mixing studies are required to distinguish factor deficiencies from inhibitors; related to interpretation of correction with phospholipids.
    86141Antiphospholipid (anticardiolipin) antibody, IgGSerologic antiphospholipid testing often performed in the diagnostic workup when phospholipid-dependent clotting abnormalities are suspected.
    86336Platelet antibody, platelet-associated IgG (direct)May be ordered in evaluation of platelet-related causes of abnormal clotting and to correlate with platelet-neutralization findings.

    Related Modifiers

    7 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…
    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…
    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…
    22Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    208000000XPediatrics PhysicianA pediatrician is concerned with the physical, emotional and social health of children from birth to young adulthood. Care encompasses a broad spectru…
    207Q00000XFamily Medicine PhysicianFamily Medicine is the medical specialty which is concerned with the total health care of the individual and the family. It is the specialty in breadt…
    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…
    2081H0002XHospice and Palliative Medicine (Physical Medicine & Rehabilitation) PhysicianA physical medicine and rehabilitation physician with special knowledge and skills to prevent and relieve the suffering experienced by patients with l…
    207T00000XNeurological Surgery PhysicianA neurological surgeon provides the operative and non-operative management (i.e., prevention, diagnosis, evaluation, treatment, critical care, and reh…
    246Y00000XHealth Information Specialist/TechnologistAn individual with a high school diploma, on-the-job experience and coding education from seminars or college classes who passes a national certificat…
    224P00000XProsthetistA health care professional who is specifically educated and trained to manage comprehensive prosthetic patient care for individuals who have sustained…
    364SE0003XEmergency Clinical Nurse SpecialistPhysician Assistants & Advanced Practice Nursing Providers · Clinical Nurse Specialist

    Related Payer Policy Updates

    Specialty: Hematology/Oncology1 / 3

    4 rows

    PolicyPayerEffective Date
    Epithelial Cell Cytology in Breast Cancer Risk AssessmentOscar Health2026-10-01
    Chemotherapy Observation or Inpatient Hospitalization (for New Mexico Only)UnitedHealthcare2026-08-01
    Antibody-Drug ConjugatesPremera Bluecross2026-08-01
    Umbilical Cord Blood Harvesting and Storage for Future Use (for Indiana Only)UnitedHealthcare2026-08-01

    Related Codes

    CPT-85002-BLEEDING-TIME-TEST-LABORATORY

    CPT 85002: Bleeding Time Test, Technical Component

    CPT-85004-AUTOMATED-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

    CPT 85004: Automated White Blood Cell Differential

    CPT-85007-MANUAL-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

    CPT 85007: Manual Differential White Blood Cell Count

    CPT-85008-BLOOD-SMEAR-MORPHOLOGIC-REVIEW-NO-DIFFERENTIAL

    CPT 85008: Microscopic Blood Smear Examination, No Differential

    CPT-85009-MANUAL-WBC-COUNT-BUFFY-COAT

    CPT 85009: Manual White Blood Cell Count Using Buffy Coat

    CPT-85013-MICROHEMATOCRIT-TEST-LABORATORY-DIAGNOSTIC

    CPT 85013: Microhematocrit Test by Tube Centrifugation

    CPT-85014-HEMATOCRIT-VOLUME-PERCENT-RED-BLOOD-CELLS

    CPT 85014: Hematocrit (Volume Percent of Red Blood Cells)

    CPT-85018-HEMOGLOBIN-ASSAY-WHOLE-BLOOD

    CPT 85018: Hemoglobin Measurement in Whole Blood

    CPT-85025-COMPLETE-BLOOD-COUNT-CBC

    CPT 85025: Complete Blood Count (CBC)

    CPT-85027-COMPLETE-BLOOD-COUNT-HGB-HCT

    CPT 85027: Complete Blood Count with Hemoglobin and Hematocrit

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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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