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    v1.0.28
    OpenPayerBilling CodesHematology and Coagulation ProceduresCPT cpt-85245-platelet-aggregation-ristocetin-vwf-assay
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    CPT 85245: Ristocetin-Induced Platelet Aggregation for VWF/FVIII

    CPT code 85245 describes a laboratory platelet aggregation test using ristocetin performed on patient plasma to evaluate von Willebrand factor and factor VIII–related platelet function; this is a specialized coagulation diagnostic service typically performed by a clinical laboratory or hematology reference lab in an outpatient laboratory or hospital 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 28-year-old woman with a history of mucocutaneous bleeding and prolonged mucosal bleeding after dental extraction is evaluated in a hematology clinic. Preliminary laboratory tests show a prolonged bleeding time and reduced von Willebrand factor antigen on initial screening. The hematologist orders specialized platelet function testing, including a ristocetin-induced platelet aggregation study, to assess platelet–von Willebrand factor interaction and to help distinguish von Willebrand disease subtypes or platelet-type von Willebrand disease.

    Specimen collection is venous plasma drawn into appropriate anticoagulant tubes and processed by the clinical laboratory. The laboratory analyst performs 85245 (platelet aggregation with ristocetin) using patient platelet-rich plasma and ristocetin reagent, recording aggregation responses at multiple concentrations. Results are reviewed by the hematology team to correlate with antigen and activity assays (e.g., VWF antigen, VWF activity, and factor VIII levels) and the patient’s clinical history to guide diagnosis and management planning. Typical sites of service include hospital outpatient laboratories, reference laboratories, and specialized coagulation/hematology laboratories in tertiary centers.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    85307Platelet function assay (for example, platelet aggregation, epinephrine, or ADP)Often performed alongside 85245 to evaluate platelet aggregation responses to other agonists (ADP, epinephrine) for comprehensive platelet function assessment.
    85241Platelet aggregation; additional agonists (per each)Used when multiple agonists beyond ristocetin are tested; billed per additional agonist concentration.
    85380Von Willebrand factor antigen assayPerformed in the diagnostic workup for suspected von Willebrand disease and correlated with ristocetin aggregation results.
    85610Prothrombin time, plasma (PT)Routine coagulation screening test often ordered before specialized platelet function testing to assess global coagulation status.
    86255Fibrinogen assayMay be ordered to evaluate quantitative fibrinogen contribution to bleeding disorders in the differential diagnosis.
    87205Platelet count by automated methodPerformed prior to aggregation studies to ensure adequate platelet count and sample quality.

    Related Modifiers

    9 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…
    50Modifier –50 (Bilateral Procedure) is appended to a CPT code when an identical procedure is performed on paired anatomical structures during the same operative session. The AMA states to add…- Use modifier -50 when the same CPT surgical, diagnostic, or radiology procedure is performed on paired anatomical structures (both sides of the body) during the same operative/session by the same…
    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…
    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…
    76Modifier -76, Repeat Procedure or Service by Same Physician or Other Qualified Health Care Professional, is appended when the same provider performs an identical, medically necessary procedure or…- Use modifier -76 when the same physician or other qualified health care professional performs an identical procedure or service a second (or subsequent) time on the same date of service and the…
    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…
    95Modifier 95 indicates that a service was provided via synchronous, real‑time audio‑video telehealth rather than in‑person. Per CMS, AAPC and professional associations, append modifier 95 to claim…- Use modifier 95 to indicate a service was furnished via synchronous, real‑time audiovisual telehealth (a live audio‑video conference between patient and provider) rather than in‑person. - Pair…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207RH0000XHematology (Internal Medicine) PhysicianAn internist with additional training who specializes in diseases of the blood, spleen and lymph. This specialist treats conditions such as anemia, cl…
    2080P0206XPediatric Gastroenterology PhysicianA pediatrician who specializes in the diagnosis and treatment of diseases of the digestive systems of infants, children and adolescents. This speciali…
    174400000XSpecialistAn individual educated and trained in an applied knowledge discipline used in the performance of work at a level requiring knowledge and skills beyond…
    207L00000XAnesthesiology PhysicianAn anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
    2085R0203XTherapeutic Radiology PhysicianTherapeutic Radiology certificate name was changed to Radiation Oncology. Use Radiation Oncology.
    111NR0400XRehabilitation ChiropractorRehabilitation is the discipline focused on restoring a patient's functional abilities to pre-injury or pre-disease status. Functional abilities are d…
    363LF0000XFamily Nurse PractitionerPhysician Assistants & Advanced Practice Nursing Providers · Nurse Practitioner
    163WX1500XOstomy Care Registered NurseNursing Service Providers · Registered Nurse

    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

    Showing 1–10 of 99

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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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