Purpose Patients treated with warfarin for therapeutic anticoagulation present a challenge for the perioperative management of urgent and emergent surgery. Anticoagulation must be reversed prior to most surgical procedures to prevent intraoperative bleeding. The purpose of this module is to review the options for urgent reversal of warfarin anticoagulation and the indications for each reversal agent. Selection of the appropriate agent is important to reduce unnecessary complications of treatment and to achieve optimal reversal of anticoagulation. Principal findings When urgent surgery is required for patients taking warfarin, intravenous vitamin K 1 should be used for procedures that can be delayed for six to 12 hr. Vitamin K 1 results in the activation of existing clotting factors rather than requiring the synthesis of new proteins, which allows for its relatively rapid onset of action. Intravenous vitamin K 1 acts more quickly than oral administration, with reversal of anticoagulation occurring within six to 12 hr vs 18-24 hr, respectively. If surgery cannot be delayed, prothrombin complex concentrates (PCCs) should be given, and intravenous vitamin K 1 should be infused concurrently to ensure sustained reversal of anticoagulation. The duration of action of both PCCs and plasma is six hours due to the short half-life of factor VII. Prothrombin complex concentrates contain small amounts of heparin and are contraindicated in patients with heparin-induced thrombocytopenia. Plasma should be used only if PCCs are unavailable or are contraindicated. Conclusion Reversal of warfarin anticoagulation can be achieved in a safe and timely manner when the appropriate agent is selected and administered correctly. Objectives of this Continuing Professional Development (CPD) module:After reading this module, the reader should be able to: 1. Identify the options for emergency reversal of warfarin anticoagulation; 2. Describe the dose, onset, and duration of action of agents that reverse warfarin anticoagulation; 3. List potential complications and contraindications of agents that reverse warfarin anticoagulation; 4. Choose the optimal agent for emergency reversal of warfarin anticoagulation, considering the timing of the operation and the risks and benefits of each agent.Despite increasing use of novel agents, warfarin remains the most widely prescribed oral anticoagulant in clinical use. A recent analysis of prescribing trends following regulatory approval for the newer agents showed that warfarin still accounted for over 75% of all the oral anticoagulants used. 1 Warfarin is indicated to reduce the risk of thromboembolic events in patients with atrial fibrillation, mechanical heart valves, and deep venous thrombosis, among other indications. Therefore, as the population ages, the use of anticoagulants, including warfarin, is projected to increase substantially.Patients treated with warfarin for therapeutic anticoagulation present a challenge for the perioperative management of urgent and emergent surgery. In order to...