There are coagulation and anticoagulation systems in human blood. Under normal circumstances, the two maintain a dynamic balance to ensure the normal flow of blood in the blood vessels, and will not form thrombus. In the case of low blood pressure, lack of drinking water, etc., the blood flow will be slow, the blood will be concentrated and viscous, the coagulation function will be hyperactive or the anticoagulation function will be weakened, which will break this balance and make people in a "thrombotic state". Thrombosis can occur anywhere in the blood vessels. The thrombus flows with the blood in the blood vessels. If it stays in the cerebral arteries and blocks the normal blood flow of the cerebral arteries, it is a cerebral thrombosis, which will cause an ischemic stroke. The coronary vessels of the heart can induce myocardial infarction, in addition, lower extremity arterial thrombosis, lower extremity deep venous thrombosis, and pulmonary embolism.

Thrombosis, most of them will have serious symptoms at the first onset, such as hemiplegia and aphasia due to cerebral infarction; severe precordial colic in myocardial infarction; severe chest pain, dyspnea, hemoptysis caused by pulmonary infarction; It can cause pain in the legs, or a cold feeling and intermittent claudication. Very serious heart, cerebral infarction and pulmonary infarction can also cause sudden death. But sometimes there are no obvious symptoms, such as the common deep vein thrombosis of the lower extremity, only the calf is sore and uncomfortable. Many patients think it is due to fatigue or cold, but they do not take it seriously, so it is easy to miss the best time for treatment. It is especially regrettable that many doctors are also prone to misdiagnosis. When typical lower extremity edema occurs, it will not only bring difficulties to the treatment, but also easily leave sequelae.