What are the common causes of thrombosis?

Common causes of thrombosis mainly include the following three factors: 1. **Vascular endothelial cell injury**: This is the most important and common cause of thrombosis. When vascular endothelial cells are damaged, the subendothelial tissue is exposed, activating the coagulation system, leading to platelet aggregation and fibrin deposition, ultimately forming a thrombus. This situation is commonly seen in diseases such as atherosclerosis, rheumatic and infective endocarditis. 2. **Abnormal blood flow status**: Slow blood flow and formation of vortices favor thrombus formation. In situations such as heart failure, prolonged bed rest, or after surgery, blood flow slows down, making it easier for blood to locally pool and coagulate into a thrombus. Blood flow is fast in the heart and arteries, making thrombus formation less likely. However, in certain specific locations such as the left atrium in mitral valve stenosis, within aneurysms, or at vascular branch points, slow blood flow and vortices can promote thrombosis. 3. **Increased blood coagulability**: When the number of platelets and coagulation factors in the blood increases, or when the activity of the fibrinolytic system decreases, the blood enters a hypercoagulable state, making thrombus formation more likely. This condition is commonly seen in hereditary and acquired hypercoagulable states, such as thrombocytosis, polycythemia vera, and malignant tumors.