Before having any surgery your doctor may order blood tests to determine how quickly your blood clots, known as a coagulation study. A PT test may also be ordered when a patient who is not taking anti-coagulant drugs has signs or symptoms of a bleeding disorder.
The Prothrombin Time blood test, or PT test is done to evaluate the blood for its ability to clot. It is often done before surgery to evaluate how likely a patient is to have a bleeding or clotting problem during or after surgery. INR, which stands for International Normalized Ratio, is the standard unit used in reporting the results of a PT test.