If there is activated thrombus formation in the blood vessels of the human body, D-dimer will be elevated, such as myocardial infarction, cerebral infarction, pulmonary embolism, venous thrombosis, as well as surgery, tumor, diffuse intravascular coagulation, infection, tissue necrosis, etc. The main reason is that D-dimer is a metabolite produced by thrombin in the coagulation process, and a high D-dimer can The main reason is that D-dimer is a metabolite of prothrombin in the coagulation process. However, the sensitivity of this indicator is high and the specificity is low, generally the normal value will be less than 200μg/L. If it is greater than 500μg/L, coupled with the manifestation of clinical symptoms, such as acute chest pain, coughing blood and syncope, the possibility of pulmonary heart failure disease cannot be excluded. Therefore, D-dimer is a peripheral thrombotic disease, especially when used as a confirmatory diagnosis of diffuse intravascular coagulation DIC, and special attention should be paid to exclude it by the patient’s condition and its test results and imaging evidence.