How to prepare a patient treated with warfarin for surgery?

The perioperative management of patients treated with warfarin should be based on the evaluation of the individual risk of thrombotic

complications and bleeding. The patients undergoing procedures associated with low risk of major bleeding (dental procedures, cataract

surgery, etc.) don‘t need any alteration of the anticoagulation; it’s however prudent to ascertain the INR seven days and one day prior to

the procedure to avoid the overanticoagulation. In patients undergoing all other invasive procedures the therapy with warfarin should

be stopped; bridging with low molecular weight heparin is required in some of them. The inherent risk of venous or arterial thromboembolism

is related to the underlying condition (reason for the anticoagulation). The risk of venous thromboembolism is in addition

increased by the surgery (postoperative risk). Preoperatively, the strategy is determined by the inherent risk of thrombosis. The therapy

with warfarin should be interrupted 5 days prior to the procedure. If the INR 1 day before surgery is ≥ 1.5, administering 1–2 mg of oral

vitamin K is suggested. In patients with low inherent risk no preoperative pharmacological thromboprophylaxis is needed. In patients

with high inherent risk (recent, idiopathic, recurrent, or paraneoplastic venous thromboembolism, mechanical heart valve prosthesis,

intermediate and high-risk atrial fibrillation) full dose of LMWH should be started immediately as the INR falls below 2.0. Therapy with

LMWH should be stopped 24 hours before surgery. In patients with intermediate inherent risk (provoked venous thromboembolism

older, than 6 weeks) prophylactic dose of LMWH should be started as the INR falls below 2.0; the last prophylactic dose should be administered

approximately 12 hours before surgery. The postoperative management is determined by the postoperative risk adjusted

according to the inherent risk and to the risk of bleeding. The prophylactic dose of LMWH is restarted usually 6–12 h post procedure,

when the haemostasis is secured. In patients with high inherent risk of venous thromboembolism and in patients with intermediate or

high risk of arterial thromboembolism the dose of LMWH should be increased to the therapeutic dose 48–72 hours after the end of the

surgery, if the haemostasis is secured. Warfarin is usually restarted in the evening of the day of procedure, or in the 1st postoperative day.

In patients requiring urgent surgery, the reversal of the effect of warfarin is necessary, if the INR is ≥ 1.5; the administration of low-dose

vitamin K (5 mg) orally or intravenously is recommended for them. For more immediate reversal of the anticoagulant effect treatment

with prothrombin concentrate is recommended (especially in patients requiring the surgery within ≤ 12 hours).

Keywords: warfarin, surgery, LMWH, vitamin K, bleeding