Well, what we do at our clinic is fairly straight-forward (I think so, anyways). We generally see the patients w/ the doctor to review whatever issues the patient has along with a review of coumadin use. In this case we just bill an office visit. Protimes (85610) are drawn monthly to make sure INR levels are good (generally dx codes 415.19, 427.31, 453.40, V12.59, and V43.3 are used). Then periodic visits with the doc are made to make adjustments to meds/care plan as applicable.
Hope this helps...