CPT 85335: Coagulation Factor Inhibitor Assessment Using Plasma - OpenPayer

Summary & Overview

CPT 85335: Coagulation Factor Inhibitor Assessment Using Plasma

CPT code 85335 covers a laboratory procedure that evaluates patient plasma after a positive coagulation factor inhibitor screen to determine the presence and effect of inhibitory antibodies against clotting factors. This test is clinically important because it helps distinguish true factor deficiencies from inhibitor-mediated dysfunction, guiding subsequent management of bleeding and anticoagulation issues. Nationally, such specialized coagulation testing is concentrated in hospital and reference laboratories and can affect clinical decisions across inpatient and outpatient settings.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an explanation of the clinical context for CPT code 85335, typical sites of service, and commonly reported modifiers. The publication provides benchmarks and coverage patterns where available, summarizes relevant billing considerations, and highlights clinical implications for interpreting inhibitor assay results. Data limitations: when specific payer policy details, taxonomies, or ICD-10 pairings are not provided in the input, the report notes those fields as not available. The material is intended to inform billing, coding, and policy staff about the clinical purpose and billing context of CPT code 85335 at a national level.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare85335CPTcoagulationlaboratoryinhibitor-screenhematologyreference-lablaboratory-testing

Billing Code Overview

CPT code 85335 describes a laboratory procedure in which a lab analyst uses patient plasma to evaluate the results of a positive coagulation factor inhibitor screen. The service is a specialized coagulation laboratory test performed to clarify the presence and impact of inhibitory antibodies against clotting factors.

Service Type: Specialized coagulation laboratory testing

Typical Site of Service: Clinical laboratory or hospital laboratory setting

Data not available in the input for payers, associated taxonomies, ICD-10 diagnoses, and related codes.

Clinical & Coding Specifications

Clinical Context

A 52-year-old inpatient presents with spontaneous bruising and prolonged bleeding after a minor dental procedure. Initial coagulation studies demonstrate an isolated prolonged activated partial thromboplastin time (aPTT) that does not fully correct on a mixing study, suggesting a possible coagulation factor inhibitor. A plasma specimen is sent to the hospital clinical laboratory for specialized testing. The laboratory analyst performs an assay using patient plasma to assess the results of a positive coagulation factor inhibitor screen (neutralization or Bethesda-type assay) to quantify inhibitor titer and identify the specific factor affected (commonly factor VIII).

Typical clinical workflow:

Clinician orders coagulation studies for bleeding evaluation, which include aPTT and prothrombin time (PT).
If aPTT is prolonged and a mixing study suggests an inhibitor, the laboratory performs confirmatory testing, including factor activity assays and an inhibitor assay represented by 85335.
The laboratory analyst prepares patient plasma, performs the inhibitor assay (e.g., Bethesda or Nijmegen-modified Bethesda), records inhibitor titer, and reports results to the ordering clinician.
Results guide hematology consultation and management decisions such as immunosuppression, bypassing agents, or factor replacement.

Coding Specifications

Modifier	Description

CPT 85345: Lee and White Clotting Time Test

cpt-85670-thrombin-clotting-time-test

CPT 85670: Thrombin Clotting Time Assay

cpt-85421-fibrinolytic-plasminogen-immunoassay

CPT 85421: Fibrinolytic Plasminogen Immunoassay

cpt-85540-leukocyte-alkaline-phosphatase-and-wbc-count

CPT 85540: Leukocyte Alkaline Phosphatase and White Blood Cell Count

cpt-85441-heinz-bodies-blood-smear-stain

CPT 85441: Direct Blood Smear Stain for Heinz Bodies

cpt-85652-automated-erythrocyte-sedimentation-rate-esr-test

CPT 85652: Automated Erythrocyte Sedimentation Rate (ESR) Test

cpt-85293-high-molecular-weight-kininogen-clotting-test

CPT 85293: High Molecular Weight Kininogen (Fitzgerald Factor) Clotting Test

cpt-85046-automated-reticulocyte-count-cellular-parameters

CPT 85046: Automated Reticulocyte Count with Cellular Parameter Evaluation

cpt-85130-therapeutic-anticoagulant-level-assay

CPT 85130: Therapeutic Anticoagulant Level Assay

cpt-85410-alpha-2-antiplasmin-laboratory-test

CPT 85410: Alpha-2 Antiplasmin Assay, Laboratory Test

Showing 1–10 of 99

Taxonomy Code	Specialty	Notes
207RC0000X	Clinical Pathology	Pathologists and clinical laboratory directors who oversee coagulation testing.
207L00000X	Hematology	Hematologists who order, interpret, and manage patients with factor inhibitors.
213E00000X	Medical Laboratory Technologist	Laboratory scientists/technologists who perform specialized coagulation assays.
2080P0200X	Pediatric Hematology-Oncology	Pediatric specialists involved when pediatric patients require inhibitor testing.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D68.32`	Acquired coagulation factor VIII inhibitor	Most directly indicates an acquired inhibitor to factor VIII; testing with `85335` confirms and quantifies inhibitor titer.
`D68.4`	Von Willebrand disease	May present with abnormal coagulation testing; inhibitor assay can be part of broader hemostasis workup when abnormal screens occur.
`D68.9`	Hemorrhagic disorder, unspecified	Used when a bleeding disorder is suspected but not yet characterized; inhibitor testing helps establish cause.
`R58`	Hemorrhage, not elsewhere classified	Acute bleeding presentation prompting coagulation evaluation including inhibitor assays.
`T50.Z95A`	Adverse effect of anticoagulants, initial encounter	When anticoagulant therapy complicates coagulation testing; inhibitor testing may be necessary to differentiate drug effect vs inhibitor.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`85335`	Assay for coagulation factor inhibitor; patient plasma assay to assess results of a positive inhibitor screen	Primary procedure described; quantifies inhibitor titer and confirms presence of a factor-specific inhibitor.
`85730`	Coagulation time measurement, reported as prothrombin time (PT) and/or international normalized ratio (INR)	Often ordered earlier in the bleeding workup alongside `85335` to evaluate extrinsic pathway.
`85731`	Activated partial thromboplastin time (aPTT)	Initial screening test that frequently leads to performance of `85335` when mixing studies suggest an inhibitor.
`85376`	Coagulation factor activity assay, multiple factors, performed by one-stage clotting methods (each factor reported separately)	Performed to measure specific factor activity (e.g., factor VIII) when inhibitor is suspected; results guide interpretation of `85335`.
`85342`	Mixing study interpretation (therapeutic drug monitoring/coagulation)	Mixing studies are used before performing inhibitor assays; `85342` represents related laboratory analyses in the diagnostic sequence.

`26`	Professional component	When billing only the professional interpretation component of a laboratory procedure (rare for high-complexity lab tests but applicable if split billing applies).
`90`	Reference (outside) laboratory	When the specimen is sent to an outside reference laboratory for testing.
`91`	Repeat clinical diagnostic laboratory test	When the same test is repeated on the same day to obtain a valid result or confirm an unexpected value.
`59`	Distinct procedural service	When another distinct procedure is billed the same day and documentation supports separate services.
`52`	Reduced services	When the test is partially reduced or not fully performed as originally described.
`53`	Discontinued procedure	When the test procedure is started but discontinued for documented clinical reasons.
`78`	Unplanned return to the operating/procedure room	Rarely applicable; used if a procedural return impacts related testing when documented.
`80`	Assistant surgeon	Not typically applicable to lab testing; included only if a procedural surgery involves an assistant and linked billing exists.
`90`	Reference (outside) laboratory	When the performing lab is an outside reference laboratory; used for correct payer routing.
`QW`	CLIA waived test	Not applicable to this high-complexity test; use only if CLIA status justifies.
`TC`	Technical component	When billing only the technical component of the test if professional interpretation is billed separately.
`91`	Repeat test for reliability	When the assay is repeated to verify an inhibitor titer due to borderline or unexpected result.

OpenPayer