Warfarin-induced factor VII deficiency and the bleeding time.

The effect of warfarin-induced factor VII deficiency on the skin bleeding time was investigated in 10 consecutive patients with mean prothrombin times of 33 sec and factor VII levels of 7%. Bleeding times in all but one subject were entirely within the normal range. We conclude that warfarin administration, even to the point of prolonging the prothrombin time beyond the therapeutic range, is not associated with an abnormal bleeding time. Furthermore, from the above evidence and a review of the literature, it is considered doubtful that factor VII plays a major role in primary hemostasis.