Do you mean that you test the PT/INR after using the anticoagulant. Generally, we use INR to evaluate the effectiveness of anticoagulants and assess whether major bleeding will occur. While taking anticoagulants, the value of INR should be controlled at 2.0-3.0. You should monitor blood clotting regularly. When the INR is between 3-5 and there is no bleeding, you can reduce the dose of the drug. When INR> 5, warfarin is discontinued and warfarin antagonist-vitamin K1 is used to prevent bleeding events. When INR drops to normal level (2 <INR <3), you can reduce the dose of warfarin and start taking it again.