Pathology/Lab Coding Alert

Question: A patient with deep venous thrombosis (DVT) is on Coumadin for blood thinning. We perform a prothrombin time test once a week to monitor Coumadin levels. How should we code this?

New Jersey Subscriber

Answer: The correct code for the prothrombin time test is 85610 (Prothrombin time). If this is done in a physician office lab that operates with a certificate of waiver under the Clinical Laboratory Improvement Amendments (CLIA), then you should report the code with modifier QW (CLIA waived test).

You’ll need documentation of the patient’s DVT and Coumadin (Warfarin sodium) treatment to show medical necessity for the repeat testing. For instance, report 453.4x (…Venous embolism and thrombosis of deep vessels of lower extremity) and V58.61 (Long-term [current] use of anticoagulants).

Depending on the payer, you may be able to separately report the blood collection using a code such as 36415 (Collection of venous blood by venipuncture) or 36416 (Collection of capillary blood specimen [e.g., finger, heel, ear stick]).

Option: You should be aware of other codes that are beyond the scope of your question, but that might come into play if you meet certain requirements for prolonged Coumadin monitoring in an outpatient setting:

• 99363 — Anticoagulant management for an outpatient taking warfarin, physician review and interpretation of International Normalized Ratio (INR) testing, patient instructions, dosage adjustment (as needed), and ordering of additional tests; initial 90 days of therapy (must include a minimum of 8 INR measurements)
  
• 99364 — ... each subsequent 90 days of therapy (must include a minimum of 3 INR measurements).