evidence: Tang et al. [8] reported that 71.4% of COVID-19 patients who did not survive met the criteria for disseminated intravascular coagulation (DIC), while only 0.6% of survivors met the criteria. It is worth noting that the coagulation and fibrinolysis disorders in the pulmonary circulation and bronchoalveolar spaces may be important factors in the pathogenesis of ARDS in COVID-19. [...] In the ultrastructure, small blood vessels show duplication of basement membrane and obvious endothelial swelling, accompanied by cytoplasmic vacuolation. The report proposes that COVID-19 pneumonia is a heterogeneous disease (tracheobronchitis, DAD, and vascular injury), usually involving pulmonary blood vessels with capillary microthrombosis and inflammation and large thrombosis. Viral infection in the area of persistent active injury leads to persistent and temporal heterogeneous lung injury [49]. Autopsy of 38 cases showed that organ involvement and the characteristics of thrombosis in COVID-19 were related to immune thrombosis. In COVID-19, inflammatory microvascular thrombi exist in the lungs, kidneys, and heart, including extraneutrophil traps associated with platelets and fibrin. COVID-19 patients also show neutrophil platelet aggregation and obvious neutrophil and platelet activation patterns in the blood, which vary with the severity of the disease. The abnormal immune thrombotic regulation of SARS-CoV-2 pneumonia is related to ARDS and systemic hypercoagulability [41]. In order to determine the role of microthrombosis in COVID-19, further work is needed. [...] Disseminated intravascular coagulation - ARDS: