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.
The symptoms of edema vary depending on the location and the extent of swelling. For most types of edema, fluid builds up under the skin, causing swelling and making the overlying area stretched and shiny. Edema may be pitting or non-pitting. With pitting edema, pressing a finger against a swollen area and then removing it leaves an indentation that slowly disappears. When edema becomes more severe, the tissue swells so much that it can’t be displaced, and no indentation is left in the skin after applying pressure. This type of edema is called non-pitting. Edema that occurs over pressure points over bony areas of the body can develop into serious sores or ulcers, especially in bedridden patients.
Peripheral edema causes swelling of the ankles, feet, or legs. This type of edema is very common, especially among older adults. It is often painless, and may affect both legs. Because of gravity, the swelling is usually most severe in the lower legs, but the upper calves and thighs can be affected as well.
Pulmonary edema is a medical emergency characterized by severe difficulty breathing. Symptoms of pulmonary edema include:
- shortness of breath
- grunting while breathing
- a crackling or rattling noise in the lungs heard with a stethoscope (rales)
- excessive sweating
- abnormally pale skin (pallor)
- abnormal heartbeat or rhythm
- chest pain.
If you experience any of these symptoms, seek immediate medical attention.
Usually, edema is a symptom of another underlying condition. In such cases, the risk factors for edema are the same as those for the underlying condition. In other words, when edema is associated with serious conditions such as kidney, liver, heart, and lung disease, the risk factors for edema are the same as those for the underlying diseases. For example, smoking is a major risk factor for chronic lung disease, high blood pressure is a major risk factor for heart disease, and obesity is a major risk factor for both heart disease and diabetes. All of these risk factors, then, also increase a person’s risk of developing edema.
Edema becomes more common with age. Because many of the underlying causes of edema occur more frequently with age, edema itself also becomes more common as people get older.
Diagnosing the underlying cause is essential for treating edema effectively. When you seek treatment for unexplained edema, your physician will start by taking a medical history. The questions will focus on the timing, location, severity, and duration of your symptoms. Your physician will also ask questions to determine whether you have had any other signs or symptoms of kidney, liver, thyroid, lung, or heart disease that may help in diagnosing the underlying cause of your swelling.
Your doctor will then perform a physical examination. The examination is likely to be extensive, and will include listening to your heart and lungs, examining your skin and nails, testing your skin tone and its response to pressure, and looking at the whites of your eyes. The purpose of the exam is to determine whether you display any signs or symptoms of heart, lung, liver, or kidney disease that may be causing your edema.
Blood and urine tests will help your physician determine whether or not you have liver or kidney disease. When the kidneys are damaged, they excrete excessive amounts of protein into the urine. A urine test can detect any excess protein. Similarly, reduced blood levels of the protein albumin may indicate serious kidney disease. Blood tests can also be used to test for liver disease, heart disease, and thyroid disease that may be contributing to your edema.
Your physician may order an x-ray of your lungs to test for lung disease or pulmonary edema. Tissue damage caused by chronic lung diseases such as COPD, emphysema, or chronic bronchitis is usually visible on a chest x-ray. In addition, the x-ray can also determine whether fluid is building up in the air sacs of your lungs, resulting in pulmonary edema.
In cases where heart disease is a suspected cause of the edema, your physician may order cardiac tests.
- Electrocardiogram. An electrocardiogram (ECG) is a test that records the electrical impulses of the heart. It can show any type of heart rhythm disturbances.
- Echocardiogram. An echocardiogram uses sound waves that are transmitted to the heart, and is essentially the same technology used in an ultrasound to observe a fetus in a pregnant woman. The echoes are produced when the waves are reflected back and turned into images by an instrument called a transducer. An echocardiogram provides very specific information about the size of the heart's chambers, the valve movements (which show whether they are closing and opening properly), and any changes in the blood vessels and other structures in and around the heart. One part of the echocardiogram, known as a “Doppler,” measures the speed and quality of the bloodflow, and can pinpoint stenosis or regurgitation.
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