A hemagglutination test is a method of examining the coagulation and fibrinolytic systems of the body. The hemagglutination test is used to find out if there are problems with the coagulation and fibrinolytic systems, to identify the cause of the problem, and to guide clinical treatment. The blood coagulation test includes several components, the most commonly used of which are coagulation time, prothrombin time, partial activation prothrombin time, fibrinogen, D-dimer, and so on. Each test represents a different clinical significance, for example, prothrombin time is a test that reflects the exogenous coagulation pathway, and an abnormal prothrombin time indicates a problem with the exogenous coagulation pathway, which is usually seen in vitamin K deficiency and other diseases. If the APTT is significantly prolonged and other indicators are normal, the most common cause of this condition is a significant prolongation of the partially activated prothrombin time due to hemophilia A or hemophilia B. Therefore, the examination of coagulation tests can provide some guidance for clinical treatment.