Coagulation function tests include plasma prothrombin time, fibrinogen activated partial thromboplastin time, plasma prothrombin time, international normalized ratio and so on. Among them, plasma prothrombin time mainly reflects the function of exogenous coagulation system, and its prolongation is mainly seen in congenital reduction of coagulation factors and fibrinogen deficiency; activated partial thromboplastin time is mainly an indicator of endogenous coagulation factor deficiency, and its prolongation is commonly seen in hemophilia, liver disease, DIC and so on; prolongation of plasma thrombin time is commonly seen in patients with hypofibrinogenemia and anomalous fibrinogenemia.