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Edema facts

  • Edema is a swelling, usually of the legs and feet due to the accumulation of excessive fluid in the tissues.
  • The edema that occurs in diseases of the heart, liver, and kidneys is mainly caused by salt retention, which holds the excess fluid in the body.
  • In certain liver and kidney diseases, low levels of albumin in the blood can contribute to fluid retention.
  • Heart failure, cirrhosis of the liver, and a kidney disease called nephrotic syndrome are the most common systemic diseases that cause edema.
  • Excess fluid that accumulates in the lungs is called pulmonary edema.
  • Excess fluid that accumulates in the abdominal cavity is called ascites.
  • Edema of unknown cause (idiopathic edema) occurs primarily in women.
  • Varicose veins or thrombophlebitis (a blood clot in an inflamed vein) of the deep veins in the legs causes edema that is localized to the legs.
  • Therapy for edema consists of treating the underlying conditions, restricting salt intake, and often using diuretics (medicines to induce urination).

What is edema?

The definition of edema is observable swelling from fluid accumulation in body tissues. Edema most commonly occurs in the feet, ankles and legs, where it is referred to as peripheral edema. Edema of the foot is sometimes called pedal edema. The swelling is the result of the accumulation of excess fluid under the skin in the spaces within the tissues.

All tissues of the body are made up of cells and blood vessels, and connective tissues that hold the cells together called the interstitium. Most of the body's fluids that are found outside of the cells are normally stored in two spaces; the blood vessels (as the "liquid" or serum portion of your blood) and the interstitial spaces (not within the cells). In various diseases, excess fluid can accumulate in either one or both of these compartments.

The body's organs have interstitial spaces where fluid can accumulate, and there are a number of different types of edema. An accumulation of fluid in the interstitial air spaces (alveoli) in the lungs occurs in a disorder called pulmonary edema. In addition, excess fluid sometimes collects in what is called the third space, which includes cavities in the abdomen (abdominal or peritoneal cavity - called "ascites") or in the chest (lung or pleural cavity - called "pleural effusion").

Anasarca or extreme generalized edema refers to the severe, widespread accumulation of fluid in the all of the tissues and cavities of the body at the same time.

Cerebral edema is an accumulation of excess fluid in the brain.

Medically Reviewed by a Doctor on 11/13/2015

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Edema - Effective Treatments Question: What kinds of treatments have been effective for edema?
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Edema - Signs and Symptoms Question: In addition to swelling, what were your signs and symptoms associated with edema?
Edema - Salt Intake Question: If you've had edema, in what ways do you adjust your salt intake?
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Leg Swelling: Symptom of Pitting Edema

Leg swelling generally occurs because of an abnormal accumulation of fluid in the tissues of the lower extremity. Persisting indentation of a swollen leg after pressure from a finger is known as pitting edema. Common causes of leg swelling include

  • salt retention,
  • cellulitis,
  • congestive heart failure, and
  • medication side effects.