While the PTT assesses the intrinsic limb of the coagulation system, the PT assesses the extrinsic or tissue factor dependent pathway. The INR is the PT ratio that would result if the WHO reference thromboplastin had been used in performing the test. Since this is a calculation, the INR will not be paid separately from or in addition to the PT, but is considered part of the conventional prothrombin time, 85610. Each must be justified separately. After stabilized, it would be unusual to require monitoring more often than monthly.
Usual guidelines are twice weekly for two weeks, one weekly for two weeks, and then monthly.
Documentation will be needed for medical justification. Diagnostic codes are to be used at their highest level of specificity. Fourth and fifth digits should be utilized when they are available. EMC and hard copy claims will be monitored for appropriateness and frequency. The service will be denied as screening if it is performed prior to a surgical procedure without an indication of medical necessity.