A simple and safe nomogram for the management of oral anticoagulation prior to minor surgery

In 80 consecutive, anticoagulated patients scheduled for minor surgery, we reduced warfarin daily dosage by 50% on days 4, 3 and 2 before the surgery, restoring the original dose the day immediately before surgery. The evening after surgery, patients took a double warfarin dose, and then the usual maintenance dose was reintroduced. The mean International Normalized Ratio (INR) value assessed 1 week before surgery was 2.63 (range 1.88-3.87); it decreased at the moment of performing surgery to 1.68 (range 1.42-2.20; P < 0.05 with respect to the preoperative value), and returned to 2.43 7 days after (range 1.96-3.51, P = ns with respect to the preoperative value). No significant difference was found comparing prothrombin fragment 1.2 (F1.2) levels 1 week before surgery and on the morning of surgery (0.49 ng/ml vs 0.67 ng/ml, P = ns), suggesting that no activation of blood coagulation had taken place following the reduction of anticoagulant therapy. Patients developed neither major nor minor bleeding, nor thromboembolism during the procedures or up to I month after surgery. In our experience, this method for the management of anticoagulation before minor surgery has been shown to be safe and useful, avoiding the cumbersome shift to either intravenous or subcutaneous heparin.