You should see a Vascular surgeon or a Hematologist.
No, warfarin cannot be used during pregnancy. This is because it is teratogenic (causes deformities in the fetus).
A minimum treatment time of 3 to 6 months is advocated in most cases. A universal ‘duration for therapy’ is yet to come out of consensus.
You will need to take it all your life.
INR stands for International Normalized Ratio. It is a system that has been established by the World Health Organization (WHO) and the International Committee on Thrombosis and Hemostasis for reporting the results of blood coagulation (clotting) tests. It is used for monitoring the dose of warfarin that is required to keep the blood thin enough so that it does not clot. INR of less than 1 means you are prone to clotting and if it is high (over 3.5) it means you are prone to bleeding. It is usually maintained between 2 to 3.