Australian Red Cross Blood Service

Interrupting warfarin therapy for an elective surgery

When there is a need for surgery, the risk of perioperative bleeding under continued warfarin therapy must be balanced against the risk of thromboembolism if warfarin therapy is stopped.

Many surgical procedures, depending on the site of surgery, can proceed under continued warfarin theray without undue bleeding; provided that the INR during and soon after surgery is about 1.5–2.0.

The effect of warfarin must be completely reversed for procedures where even minor bleeding might cause critical damage. For example, in neurosurgery, plastic surgery and regional anaesthesia.

It is safe to stop warfarin therapy for several days before and after surgery in patients with atrial fibrillation, previous systemic embolism or a prosthetic heart valve; because their absolute daily risk of a serious thromboembolic event is small (in most patients).(1)

High-dose therapeutic heparin for these indications is rarely indicated as the risk of bleeding is usually prohibitive.

The risk of recurrence is greatest during the first 4 weeks after venous thromboembolism; therefore, warfarin therapy should not be interrupted during this time, if at all possible.(1) However, this position is not universally accepted.

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Interrupting warfarin therapy in the emergency setting

Immediate warfarin reversal is required when there is major bleeding. It is also recommended that you consult a haematologist in these circumstances, such as the following:

• Emergency surgery

• Life-threatening or limb-threatening bleeding

• Intracranial or spinal haemorrhage

• Significant gastrointestinal haemorrhage (haematemesis and melaena)

You need to discuss the degree of anticoagulant reversal with a cardiologist for patient with prosthetic heart valves.

The following management approach is recommended in the emergency setting:

• Stop warfarin therapy

• Give 1.0–5.0 mg of vitamin K₁ (slow intravenous or oral) and should be individualised

• Give Prothrombinex-VF (25−50 IU/kg) and a small dose of fresh frozen plasma (depending on the clinical circumstance and level of the INR)

  • Fresh frozen plasma (300 mL) is given to supply factor VII

  • Prothrombinex-VF is contraindicated in patients with clinical and laboratory signs of thrombosis or disseminated intravascular coagulation (DIC)

  OR

• Give full replacement therapy with fresh frozen plasma (10–15 mL/kg)

Re-introduction of anticoagulant needs to be individualised, also taking into account the risks of bleeding and thrombosis.

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Reference

1. Gallus AS, Baker R, Chong B, et al, on behalf of the Australasian Society of Thrombosis and Haemostasis. Position statement consensus guidelines for warfarin therapy. MJA 2000;172:600–605.