The main clinical manifestation is the sudden swelling of one limb, lower limb venous thrombosis, the patient feels local pain, which is aggravated when walking, and in mild cases, the local heaviness is only felt, and the symptoms are aggravated when standing. Physical examination has the following features: 1. The development of swelling of the affected limb must be measured accurately with a tape measure every day and compared with the thickness of the healthy lower limb, and it is unreliable to rely solely on visual observation, which is of high value to confirm the diagnosis of deep vein thrombosis. Homans’ sign can cause deep pain in the calf muscle when the foot is sharply bent to the dorsal side, and Homans’ sign is often positive when there is deep vein thrombosis in the calf. This is caused by the gastrocnemius muscle and the flounder muscle when the passive extension stimulates the calf blood whole vein; 4, superficial varicose veins deep vein obstruction, can cause superficial vein pressure rise.