Lower extremity edema is caused by more lesions, so the identification is more difficult. Commonly used in the following diseases: 1, cardiogenic edema, mainly the manifestation of right heart failure, edema first appeared in the local, can be extended upward to the whole body. It is often accompanied by jugular venous distension, hepatomegaly and other symptoms. Nephrotic edema is seen in various types of nephritis and nephropathy, in which edema of eyelids and face is mostly seen in the morning, and it can develop into generalized edema later. It is often accompanied by abnormal urinalysis, hypertension, renal function impairment and other symptoms; 2, hepatic edema, seen in the liver dysfunction stage, first appeared in a large number of ascites, and later appeared in the lower limbs due to the decrease of protein caused by the symptoms of edema; 3, malnutrition edema, seen in the long term chronic wasting disease caused by nutritional deficiencies and caused by edema; 4, inflammatory edema is commonly seen in the hypothyroidism, i.e., hypothyroidism. It occurs in the lower limbs, and can also appear in the periorbital area; 5, premenstrual tension syndrome, mainly in the 7-14 days before menstruation, eyelids, ankles and hands of mild edema, can be accompanied by breast pain, after menstruation, edema can gradually decline; 6, drug edema, mainly the use of adrenocorticotropic hormones, estrogens, androgens, insulin, as well as vasodilating drugs, especially calcium antagonists can cause edema; 7, Idiopathic edema, of unknown cause, with sudden onset of bilateral limb swelling. It is mostly seen in women, and may be related to endocrine dysfunction, showing cyclic edema. 8. Edema caused by localized lesions. The edema is caused by the obstacle of blood return and lymphatic return in the lower limbs of the human body. Lymphatic edema is more serious, called rubber leg; 9, because of venous obstruction caused by edema, venous obstruction is divided into the inferior vena cava obstruction can cause double lower extremity edema, known as Buga syndrome. Another situation is bilateral iliac vein, femoral vein and other lower extremity deep vein thrombosis caused by edema, there is also a situation for venous valve insufficiency caused by edema. These edemas are more serious and require prompt hospitalization.