Abstract
The prothrombin time, activated partial thromboplastin time, thrombin time, and skin bleeding time, with assays of factors II, VII, IX, and X, platelet count, and liver function tests were performed on a group of patients receiving long term warfarin therapy. There were 17 bleeding patients and 13 non-bleeding patients. A study was made, using the Australasian Reference Thromboplastin and 2 other thromboplastic reagents in common use. The Australasian Reference Thromboplastin was shown to be more sensitive to the coumarin induced coagulation defect than rabbit brain thromboplastin, and hence of more value in preventing haemorrhagic complications. The level of factor II assayed by the one stage method was a useful independent indicator of the intensity of oral anticoagulation, and correlated well with the development of bleeding.