The risk of postoperative saphenous vein thrombosis in the left leg is generally low, but it needs to be treated promptly to avoid secondary deep vein thrombosis, which carries a risk of dislodgement and, if dislodged, can lead to pulmonary embolism, which can be life-threatening. Since saphenous vein thrombosis is a superficial vein thrombosis and is usually confined to the saphenous vein, the risk of saphenous vein thrombosis dislodgement is low. However, due to the presence of a transportation branch between the saphenous vein and the deep vein, if the saphenous vein thrombosis is not treated in time, it may spread through the transportation branch vein or directly to the deep vein, which may lead to the formation of deep vein thrombosis. The risk of DVT is also increased due to increased bed rest and surgical trauma after surgery, which can lead to hypercoagulability of the blood. If deep vein thrombosis is formed, it is extremely unstable in its early stage, and the thrombus can be dislodged very easily in case of external force or impact of blood flow, and the dislodged embolus may form a pulmonary embolism, which will lead to changes in circulatory and respiratory functions and jeopardize the patient’s life. Therefore, if there is saphenous vein thrombosis in the left leg after surgery, anticoagulant drugs, such as low molecular heparin, warfarin, etc., should be given under the doctor’s guidance in a timely manner, and attention needs to be paid to the risk of bleeding during the period of medication.