There are several causes of lower extremity swelling in the elderly: 1. cardiac insufficiency, patients with cardiac insufficiency will have lower extremity swelling, usually of both lower extremities, and combined with dyspnea, shortness of breath after exertion, and in severe cases may be complicated by telescopic breathing, nocturnal paroxysmal dyspnea, etc. 2. hepatic insufficiency, patients with hepatic insufficiency will also have lower extremity swelling in the late stage, especially in patients with combined ascites. The lower extremity swelling can assess the severity of low protein ascites, in addition, there will be nausea, vomiting and other symptoms of liver discomfort. 3, renal insufficiency, renal insufficiency is the most common cause of lower extremity swelling, renal insufficiency patients will also appear double lower extremity swelling, there will be a history of chronic kidney disease, if it is acute renal failure, will also cause lower extremity swelling. 4, lower extremity venous insufficiency Lower extremity venous insufficiency can also cause swelling of the lower extremities, which is generally relatively mild and can be unilateral or bilateral. The ultrasound results should be used to assess whether the venous insufficiency is caused by thrombosis, and if it is caused by thrombosis, it needs to be treated in the vascular surgery department of a regular hospital.