Why & How a Prothrombin Time Test is Performed? A prothrombin time (PT) test determines how long an individual’s blood plasma takes to clot. Prothrombin, also known as factor II, is one of several plasma proteins that are involved in clotting.
What is the Purpose of a Prothrombin Time Test? When an individual gets a cut and their blood vessel ruptures, blood platelets gather at the site of the wound. To stop the bleeding, they make a temporary plug. A set of 12 plasma proteins, or coagulation "factors," work together to form fibrin, which covers the wound, in order to create a strong blood clot.