CPT 85396Laboratory

Clotting assay whole blood

CPT code 85396 covers a blood test that measures how quickly your blood clots using a whole blood sample. This test helps doctors evaluate bleeding disorders or monitor blood-thinning medications.

Showing rates for

National Average

Base Medicare rate

$18.44

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

0.37

PE RVU (NF)

0.18

MP RVU

0.02

Total RVU

0.57

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Document medical necessity with specific clinical indication (e.g., 'monitoring warfarin therapy' or 'preoperative assessment for patient on anticoagulation') in the ordering physician's notes
Impact: Prevents medical necessity denials that account for 30-40% of laboratory test rejections; protects full $18.44 reimbursement
Verify CLIA certification level matches the device complexity before billing; many whole blood coagulation devices are CLIA-waived and require QW modifier
Impact: Prevents compliance violations and potential CLIA sanctions; incorrect certification level can trigger recoupment of all payments plus penalties
Bill only once per patient per day unless modifier 91 is appended with documentation justifying repeat testing for clinical management decisions
Impact: Avoids automatic denials for duplicate testing; proper use of modifier 91 can secure additional $18.44 per medically necessary repeat test
Ensure linkage to appropriate diagnosis codes such as Z79.01 (long-term anticoagulant use), I48.91 (atrial fibrillation), or Z01.812 (preoperative lab exam) to establish medical necessity
Impact: Diagnosis-to-procedure matching reduces denial rate by 25%; screening without symptoms typically denied without preventive diagnosis code
Do not bill 85396 with comprehensive coagulation panels (85610) on same specimen as it is typically included; verify payer-specific bundling edits
Impact: Prevents unbundling denials and potential fraud investigations; inappropriate duplicate billing can trigger 100% recoupment plus interest
Maintain quality control documentation and device calibration logs as these are commonly requested during audits of point-of-care testing

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Frequently asked questions

What is the Medicare reimbursement rate for CPT 85396 in 2025?

The 2025 Medicare national average reimbursement for CPT 85396 is $18.44 for both facility and non-facility settings, based on 0.57 total RVUs and the conversion factor of 32.3465.

How many times can you bill CPT 85396 on the same day?

You can bill CPT 85396 multiple times on the same day only when medically necessary and documented, using modifier 91 for each repeat test performed to obtain subsequent values for patient management decisions. Without modifier 91, duplicate same-day tests will typically be denied.

What is the difference between CPT 85396 and 85610?

CPT 85396 is a clotting assay performed on whole blood (typically point-of-care testing), while 85610 is prothrombin time (PT) performed on plasma in a traditional laboratory. The tests use different methodologies and specimens, though both assess coagulation function.

Do I need modifier QW when billing CPT 85396?

Yes, modifier QW is required when CPT 85396 is performed using a CLIA-waived point-of-care device. The modifier indicates the test is categorized as waived under CLIA and affects compliance reporting, though it does not change the reimbursement amount.

What diagnosis codes support medical necessity for CPT 85396?

Common supporting diagnosis codes include Z79.01 (long-term anticoagulant use), I48.91 (atrial fibrillation), Z01.812 (preoperative lab exam), D68.9 (coagulation defect), and I26.99 (pulmonary embolism). The diagnosis must demonstrate clinical necessity for coagulation assessment.

Is CPT 85396 covered for routine screening without symptoms?

No, Medicare and most payers do not cover CPT 85396 for routine screening in asymptomatic patients without risk factors. Coverage requires documented medical necessity such as anticoagulation monitoring, preoperative assessment, or evaluation of bleeding/clotting symptoms.

What are the CLIA requirements for billing CPT 85396?

The facility must hold valid CLIA certification appropriate for the device complexity level (waived or moderate). Required documentation includes quality control logs, device calibration records, personnel competency assessments, and procedure manual. CLIA certificate number must appear on test reports.