Deep vein thrombosis is a serious complication for obstetrics and gynecology patients. If pulmonary embolism occurs, it will endanger the patient's life. Venous thrombosis (venous thromboembolic disease, venous thromboembolic disease) includes two types: ① thrombophlebitis (thrombophlebitis), which is caused by inflammatory reactions of the venous wall lining due to various reasons, resulting in thrombosis. The thrombus adheres tightly to the wall and is not easy to fall off. ② Venous thrombosis (venous thrombosis), which is generally believed to be mainly caused by slow blood flow and hypercoagulable state of blood. Most of them are located in deep veins. The thrombus adheres lightly to the wall and is easy to fall off and cause pulmonary embolism. After thrombosis, most of them stimulate the inflammatory response of the vein, making the thrombus adhere more tightly to the wall. Some scholars also believe that these two lesions may be different stages of a disease, which are sometimes difficult to distinguish, so they are collectively referred to as venous thrombosis.