D-dimer is D-dimer, which is a fibrin degradation product and a better indicator for diagnosing active fibrinolysis.The clinical significance of D-dimer measurement includes the diagnosis of thrombogenic diseases, prognosis of surgical patients and monitoring of thrombolytic drug therapy. 1. Diagnosis of thrombogenic diseases: When thrombus is formed, the fibrinolytic system of the body is activated, and fibrin is degraded into various fragments, including D-dimer, so the elevation of D-dimer is of great significance in the diagnosis of thrombogenic diseases. Thrombogenic diseases include DIC, pulmonary embolism, deep vein thrombosis, and acute heart attack. 2. Determination of prognosis of surgical patients: there is microthrombosis and enhanced fibrinolytic activity in the body of post-surgical patients. Therefore, the monitoring of D-dimer level is of great significance in determining the prognosis of patients. 3. Thrombolytic drug therapy monitoring: under the action of thrombolytic drugs, thrombus is rapidly dissolved, and D-dimer in the blood rises significantly. Therefore, it is of great clinical significance to dynamically monitor the therapeutic effect of thrombolytic drugs before, during and after the use of thrombolytic drugs. In addition to the above significance, the level of D-dimer also has important clinical significance in liver diseases, malignant tumors and other diseases. When there is an abnormality of blood D-dimer, one should consult a doctor in time and under the doctor’s guidance, carry out the appropriate examination to make a diagnosis and treatment.