1, early manifestation of the calf belly pain, especially in the dorsal curvature of the foot when the pain increased. At the same time, there is pressure pain in the muscles of the calf belly. 2.The swelling of the foot and calf will appear, also accompanied by the deepening color of the skin suit, which is caused by the venous blood cannot return in time. With the development of deep vein thrombosis, the degree of swelling of lower limbs will become heavier and the scope of swelling will become larger, and finally there will be swelling of the whole lower limbs including the thighs. 3.As the swelling of the lower limb increases, the skin of the lower limb becomes dark purple and may become pale as it continues to develop, and the limb is extremely swollen. Once the thrombus in the deep vein is dislodged it will flow back to the right heart and then enter the pulmonary artery, causing pulmonary embolism, which can be life-threatening in serious cases. According to current research, the chance of pulmonary embolism due to deep vein thrombosis is much higher than we think, and there are many without obvious symptoms, but its recurring nature tends to cause multiple pulmonary solids and eventually pulmonary failure.