There is no clear clinical data on the symptoms of the precursors of thrombosis, and the symptoms usually vary according to the location of the lesion. Usually, thrombosis is divided into deep vein thrombosis, cerebral thromboembolism, pulmonary thromboembolism and so on according to the site of complication. Generally, deep vein thrombosis occurs in the lower limbs, and patients often experience muscle spasms, pain and swelling of the affected limbs, which may be accompanied by dry and reddened skin, etc. Cerebral thromboembolism, on the other hand, is characterized by the presence of a cerebral thrombosis. Cerebral thromboembolism is characterized by limb weakness, numbness, intracranial hypertension, hemiparesis and seizures. In the case of pulmonary thromboembolism, patients may experience chest or upper back pain, which may also be accompanied by a dry cough, dizziness, rapid heartbeat and shortness of breath. And blood clots may also occur in the blood vessels of the abdominal organs, which can lead to indigestion, intestinal obstruction, abdominal distension, emaciation, blood in the stool, and acute gastrointestinal bleeding. It is recommended that after the occurrence of thrombus, patients should clarify the site of thrombus in time and take reasonable treatment measures under the guidance of doctors to avoid causing serious consequences.