Wet gangrene of the lower limbs is the most serious type of deep vein thrombosis of the lower limbs, in which the entire venous system of the lower limbs, including potential side branches, is almost entirely in a state of obstruction, with a sharp rise in venous pressure, severe pain in the limbs accompanied by marked swelling of the entire affected limb, shiny and cyanotic skin, lowered skin temperature, and severe swelling of the affected limb, ischemia to the point of necrosis, as a result of arteriosclerosis and/or interstitial syndromes. It is generally recognized that acute deep vein thrombosis enters the sequela phase after 3 to 6 months. DVT undergoes resorption and polarization, as well as a slow process of recanalization, which is less likely the more proximally located the thrombosis is. According to Dale, the recanalization rate of ilio-femoral vein thrombosis is about 1% to 2%. In addition, thrombus in the process of recanalization, the valve can be destroyed, and reflux lesions. In addition to obvious limb swelling, due to long-term deep venous return obstacle, calf deep venous hypertension, more involved in the traffic branch makes the lower limb superficial varicose veins more and more obvious, the boot area can be due to the skin nutritional disorders of chronic eczema, hyperpigmentation, and even stagnant ulcers. So what is the pathologic etiology of wet gangrene of lower limb? Pathological causes 1, blood flow stagnation state: due to prolonged illness bedridden, trauma or fracture, larger surgery, pregnancy, childbirth, long-distance car or airplane sedentary, or long time sitting and squatting, etc. can make the blood flow slow, stagnation, and promote venous thrombosis of the lower limbs. 2.High coagulation state of blood: such as trauma, post-surgery, extensive burns, pregnancy, postpartum, etc. can make platelets increase, adhesion enhancement, easy to form thrombus. 3.Injury to the vein wall: when the vein wall is affected by any factors, such as mechanical, infectious and chemical injuries, the collagen in the basement membrane and connective tissue under the endothelium of the vein will be exposed, and the platelets will then adhere to it and aggregate, and release many biologically active substances, such as catecholamines, 5-hydroxytryptamine, etc. At the same time, under the action of platelet thrombin, the formation of prostaglandins through arachidonic acid will be carried out. PGG2, PGH2 and other substances, these substances can aggravate the aggregation of platelets, which is conducive to the formation of thrombus. 4, other factors: such as age, obesity and anti-activation protein C.