Summary & Overview
CPT 85611: Prothrombin Time (PT) Test
CPT code 85611 represents the prothrombin time (PT) laboratory test, a common coagulation assay that measures how long plasma takes to clot after addition of a specific test plasma fraction. Nationally, PT testing is a routine diagnostic and monitoring tool relevant to anticoagulation management, evaluation of bleeding disorders, and assessment of liver function, making it widely used across inpatient and outpatient laboratory settings.
Key payers included in this analysis are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find clinical context for the test, typical sites of service, and coverage considerations relevant to major commercial and public payers. The publication provides benchmarks and operational metrics where available, summarizes payer coverage patterns, and highlights policy factors that affect coding and reimbursement for laboratory coagulation testing.
The piece is intended to help billing, laboratory, and compliance teams understand the role of CPT code 85611 in clinical workflows and payer interactions. Data not available in the input will be noted explicitly in dedicated sections.
Billing Code Overview
CPT code 85611 describes a prothrombin time (PT) test, a laboratory procedure in which a lab analyst measures the time it takes for a patient’s plasma sample to clot after mixing the specimen with a specific test plasma fraction. The result evaluates the extrinsic and common coagulation pathways and is commonly used to assess bleeding or clotting disorders, monitor anticoagulant therapy, and help diagnose liver disease.
Service Type: Clinical laboratory diagnostic test
Typical Site of Service: Clinical laboratory or hospital laboratory
Clinical & Coding Specifications
Clinical Context
A 64-year-old male with atrial fibrillation on warfarin presents for routine laboratory monitoring. A phlebotomy technician draws blood into a sodium citrate tube; the sample is delivered to the clinical laboratory. The lab analyst performs a 85611 prothrombin time (PT) by mixing the patient plasma with a standardized thromboplastin reagent and measuring the time to clot formation. Results are used to calculate the international normalized ratio (INR) when applicable and reported to the ordering clinician. Typical workflow steps include specimen accessioning, plasma preparation (centrifugation), performance of the PT assay on an automated coagulation analyzer, quality control checks, result verification by a licensed laboratory professional, and reporting to the electronic health record and the ordering provider. Typical site of service is an outpatient laboratory, hospital clinical laboratory, or ambulatory clinic with laboratory capabilities.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation/oversight of the test separate from the technical performance. |
TC |