Clinically, there are often several methods to check whether the patient has edema. One can observe whether the limbs on both sides of the patient are of the same thickness, and generally the side that is obviously swollen is caused by edema, and the common causes are unilateral lower limb swelling caused by deep vein thrombosis. If the limbs on both sides of the patient are equal in thickness but are obviously swollen, local pressure can be applied at this time if there are obvious indentations, which can also determine that the patient is accompanied by swelling of both lower limbs, mostly seen in sunken edema caused by renal insufficiency and hypoproteinemia. Third, if the patient has obvious thickening of both limbs, but no sunken edema, it can be found through ultrasound examination that the subcutaneous tissue is accompanied by more exudate, which can also confirm the diagnosis of edema.