  The patient is an 82-year-old Caucasian female admitted to the Hospital for elective total left knee arthroplasty.  At the time of admission, the patient has a normal prothrombin time and INR of 13.4 seconds and 1.09 respectively and postoperatively, she was placed on Coumadin which is the usual orthopedic surgery procedure for reducing the risk of postoperative thromboembolic activity.  However, the patient's prothrombin time and INR rapidly rose to supratherapeutic levels.  Even though Coumadin was discontinued on 01/21/09, the patient's prothrombin time and INR has continued to rise.  Her prothrombin time is now 83.3 seconds with an INR of 6.52.  Hematology/Oncology consult was requested for recommendation regarding further evaluation and management.