American College of Physicians: Internal Medicine — Doctors for Adults ®


Billing guidelines for anticoagulant monitoring

From the July/August 2000 ACP-ASIM Observer, copyright 2000 by the American College of Physicians-American Society of Internal Medicine.

By Brett Baker

Q: When I bill for a prothrombin time test using the current procedural terminology (CPT) code 85610, my reference laboratory wants me to provide an International Classification of Diseases, Ninth Revision (ICD-9) code for the disease process (e.g. atrial fibrillation, pulmonary embolism) as the primary diagnosis. Is this correct?

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A: No. You should report ICD-9 code V58.61, long-term (current) use of anticoagulants, as the primary reason for ordering a prothrombin time test. You should report the ICD-9 code indicating the condition for which an anticoagulant is prescribed as a secondary diagnosis. ICD-9 code 427.31 (atrial fibrillation) and 415.10 (pulmonary embolism and infarction) are examples of codes that could be used as a secondary diagnosis.

Another common misconception is that ICD-9 code V67.51, follow-up examination after completed treatment with high-risk medication, not elsewhere classified, is appropriate to justify a prothrombin time and other tests for patients on high-risk medications. According to the American Hospital Association's Coding Clinic (fourth quarter, 1995), V67.51 should be reported only for patients who have completed their drug treatment.

Q: How does Medicare pay physicians for monitoring patients who are on anticoagulant drugs?

A: When physicians use a prothrombin time test to monitor patients on anticoagulant drugs, Medicare pays the entity that performed the test. Payment is based on the geographically specific schedule of fees for laboratory tests.

Payment for anticoagulant monitoring-related services is considered part of the payment for an evaluation and management (E/M) service. Anticoagulant monitoring services that are bundled into payment for an E/M service include interpreting test results, evaluating the patient and adjusting dosages.

The following scenarios illustrate how Medicare reimburses physicians for anticoagulant monitoring:

  • No separate bill for anticoagulant monitoring. A physician who calls a patient to relay test results and schedule the next prothrombin time test cannot bill a separate E/M service. Medicare does not pay separately for telephone contact with patients. Instead, it includes an assigned value for typical telephone follow-up associated with a patient visit in the overall payment for the separately billable E/M service. In other words, Medicare payment for your time spent phoning a patient is included in the amount you receive for the face-to-face encounter that preceded the call.
  • Billing for the lowest level office/outpatient E/M service, CPT 99211. Physicians can bill CPT 99211 when a nurse (or other office personnel) meets with a patient in the office to discuss the prothrombin time test results and schedule the next test. To bill using CPT 99211, the physician does not have to be present, but should be available if needed.
  • Billing for a low- to mid-level office/outpatient E/M service, CPT 99212-99213. Physicians can bill a low-to mid-level E/M service if they discuss the prothrombin time test results with the patient during an office visit. A physician may choose to personally relay the results if he or she needs to evaluate the patient and adjust the anticoagulant drug dosage.
  • Billing for a mid- to high-level office/outpatient E/M service, CPT 99213-99215. Physicians can bill a mid- to high-level E/M service if they discuss the prothrombin time test results with the patient during an office visit for an unrelated problem. The physician should consider the prothrombin time test-related activities of relaying results and adjusting dosage when determining the appropriate level of service to bill for evaluating and treating the ailment that brought the patient to the office (e.g. hypertension, arthritis). The prothrombin time test-related activities are likely to warrant billing a higher level of service than is appropriate for evaluating and treating an acute illness or monitoring a chronic condition alone.

Brett Baker is a third-party payment specialist in the College's Washington Office. If you have questions on third-party payment or coding issues, call him at 202-261-4533, send a fax to 202-835-0441, or send an e-mail to

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