PT in medical terms indicates prothrombin time, which is a more sensitive indicator of the human coagulation system and mainly reflects whether the exogenous coagulation function is abnormal. The normal value of 11-15 seconds, if prolonged for more than three seconds indicates a meaningful. Prolonged prothrombin time after the patient has bleeding, there is trauma blood is not easy to stop, can lead to extensive bleeding and oozing of blood in the body. It is commonly seen in the following types of diseases: 1. congenital coagulation factor deficiency, such as lack of factor V, factor VII, factor X. 2. acquired coagulation factor deficiency, such as primary fibrinolytic hyperfunction, and severe liver disease. Prolonged prothrombin time can also result when heparin is used in humans.