8. RECOMMENDATIONS FOR PREOPERATIVE AND POSTOPERATIVE ANTICOAGULATION IN PATIENTS WHO ARE TAKING ORAL ANTICOAGULANTS

8.1 WARFARIN

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8.1.1 Warfarin should be ceased for four (4) days prior to planned surgery, i.e. 4 doses omitted.

8.1.2 The INR should be measured the day before surgery. If the INR is >1.5, then 1mg only of Vitamin K should be administered intravenously (i.e. dilute 10mg in 10mls and inject 1ml.

8.1.3 If the INR is < 1.5, surgery is safe to undertake.

8.1.4 Warfarin should be recommended post-operatively at the patient's regular dose, with no loading dose. It should be restarted either on the evening of the day of surgery or the day after surgery.

8.2 HEPARIN

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A. For patients with a history of venous thromboembolism (VTE)

8.2.1 Elective surgery should be avoided in the first month after an acute episode of venous thromboembolism (VTE). If this is not possible then full dose, (I) intravenous unfractionated Heparin (IV UFH) or (II) subcutaneous low molecular weight Heparin (SC LMWH) should be given before and after the procedure while the INR is below 2.0.

Either:

8.2.2 For patients who have had a venous thromboembolism more than 1 month but less than 3 months ago, anticoagulation pre-operatively is not required. Postoperatively however, the risk of venous thrombosis remains high and so full dose anticoagulation should be administered as outlined above.

8.2.3 For patients who are on long term anticoagulants (>3 months since last episode), the risk of thrombosis is not high enough to warrant either preoperative or postoperative therapy with full dose Heparin. Subcutaneous low-dose Heparin or low-molecular-weight Heparin, in the dosage used for prophylaxis against venous thromboembolism should be administered.

B. For patients at risk of arterial thromboembolism.

8.2.1 Elective surgery should be avoided in the first month after an arterial embolism but if surgery is essential, preoperative full dose heparin should be given (as above). Postoperative Heparin is recommended for such patients only if the risk of bleeding is low.

8.2.2 In all other patients who receive anticoagulants to prevent arterial embolism, such as those with mechanical heart valves or a history of non-valvular atrial fibrillation the risk of embolism is not high enough to warrant either preoperative or postoperative therapy with full dose Heparin. Full dose Heparin therapy should in fact be avoided after major surgery because of the high risk of bleeding. Subcutaneous low-dose Heparin or low-molecular-weight Heparin, in the dosage used for prophylaxis against venous thromboembolism in high risk patients, is recommended for hospitalised patients whose risk of arterial embolism does not justify the use of full dose Heparin. However, neither hospitalisation to administer subcutaneous Heparin nor the administration of subcutaneous Heparin to outpatients appears to be justified.

RECOMMENDATIONS FOR PREOPERATIVE AND POSTOPERATIVE ANTICOAGULATION IN PATIENTS WHO ARE TAKING ORAL ANTICOAGULANTS*

* Full anticoagulation denotes either intravenous unfractionated Heparin (iv UFH) or subcutaneous low molecular weight Heparin (sc LMWH) at full therapeutic doses.

¶ Intravenous unfractionated Heparin or full dose S.C. LMWH should be used after surgery only if the risk of bleeding is low.