Hemostasis Coagulation Practice Test 2026 - Free Coagulation Practice Questions and Study Guide

Warfarin slows clotting by inhibiting vitamin K–dependent production of factors II, VII, IX, and X, which prolongs the PT. Giving vitamin K directly reverses this mechanism, allowing the liver to resume making these factors and thereby shorten the PT. Intravenous vitamin K acts fastest to start reversing the anticoagulation. Protamine sulfate reverses heparin, not warfarin. Fresh frozen plasma can provide clotting factors immediately but does not address the underlying inhibition and carries volume and compatibility considerations. Cryoprecipitate mainly supplies fibrinogen and factor VIII, not the vitamin K–dependent factors affected by warfarin.