Swelling caused by the build-up of excess fluids in the body is called edema. The swelling may be limited to specific areas like the ankles or legs, or it may be spread over large areas of the body. Edema is classified primarily by the location of the swelling. For example, peripheral edema is swelling of the ankles, feet, and legs. Pulmonary edema is accumulation of fluid in the lungs. Periorbital edema is swelling around the eyes. Massive edema (also known as anasarca) is swelling covering a large part of the body. Other body locations that may become swollen include the gums, lymph glands, face, abdomen, breasts, scrotum (in men), or the joints.
Edema is a symptom associated with several different underlying diseases. Slight swelling is usually not a serious medical problem, but edema can be a long-term, progressive manifestation of disease with serious consequences such as leg ulcers.
A wide variety of medical conditions can cause edema, including kidney, liver, and heart disease. Several of the body's organs and glands affect fluid balance. Diseases that affect these organs and prevent them from functioning normally can cause the kidneys to retain salt and water (two major components of edema fluid). This excess fluid then “leaks” out of the body's circulatory system and into surrounding tissues, causing them to swell.
Pulmonary edema can be a complication of heart failure. Serious, inadequately treated heart failure can result in pulmonary edema. As the heart pumps less efficiently, fluid leaks out of the veins in the lungs and fills the air sacs, making it difficult to breathe. Pulmonary edema is life-threatening, and if left untreated, can rapidly become fatal. People with less severe heart failure that does not lead to pulmonary edema may also experience swelling in their ankles.
Edema may also be caused by chronic lung disease. Severe chronic lung disease—such as chronic obstructive pulmonary disease (COPD), emphysema, or chronic bronchitis—may restrict blood flow through the vessels in the lungs. This restricted blood flow creates pressure in the vessels that can back up throughout the rest of the circulatory system. The pressure causes fluid to leak into surrounding tissues, causing swelling, such as in the legs and feet.
Varicose veins may cause peripheral edema. Tiny valves in leg veins help the circulatory system move blood from the lower legs and feet back toward the heart. As people age, these valves often become weakened, resulting in blood pooling in the lower legs, forming varicose veins. The pressure from the pooling blood can cause fluid to leak into the surrounding tissue, causing swelling of the lower legs, ankles, or feet.
Sitting or standing too long may cause edema. This type of edema is called orthostatic edema. It may be aggravated by hot weather, and can occur after long automobile or airplane trips, or any time a person stands or sits in one position for a long period of time.
Several different types of medications can cause edema. These medications include oral contraceptives containing estrogen or progesterone, blood pressure medications, certain antidepressants, oral corticosteroids, and testosterone.
Swelling in the ankles and legs commonly occurs during the later stages of pregnancy. As the uterus enlarges, it puts pressure on the vena cava, a large vessel that returns blood to the heart from the rest of the body. This pressure then backs up through the circulatory system, causing increased blood pressure in the legs, ankles, and feet. Ultimately, this pressure causes fluid to leak into the surrounding tissue.
Other causes of edema include allergic reactions, sunburns, malnutrition, injury or trauma, blockages in the lymphatic system (caused by infection, inflammation, or cancer), exposure to high altitude (rare), and hormonal changes associated with menstruation (in some women). Nephrotic syndrome, in which damaged kidneys loose excess protein in the urine, can lead to severe swelling in the ankles. Severe liver disease can lead to cirrhosis and excess ankle swelling.
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