The term edema refers to the accumulation of fluid in the body. This fluid retention is also referred to as dropsy or hydropsy.

Fluid balance in the body and pathology of edema

The body contains a balanced amount of interstitial fluid, which is regulated by fluid homeostasis. Edema occurs when the amount of fluid secreted into the interstitium either increases or fails to be removed.

Some examples of factors that can cause edema include:

1. Raised hydrostatic pressure
2. Low oncotic pressure in the blood vessels
3. Increased permeability of the blood vessel walls (as seen in inflammation)
4. Impaired clearance of fluid in the lymphatic channels
5. Water and sodium retention due to impaired kidney function

Symptoms of edema

The fluid build-up may cause swelling in one particular part of the body, after an injury, for example, or may be more general. Generalized edema is usually seen in health disorders such as heart failure or kidney disease.

Symptoms include:

• Swollen and puffy skin
• Skin discoloration
• Skin that “pits” when pressed
• Stiff, tender and painful joints
• Weight gain or weight loss
• Raised blood pressure and heart rate

Types of edema

Edema can affect any part of the body but is most common in the feet and ankles, in which case it is referred to as peripheral edema. Examples of other forms of edema include:

• Cerebral edema, which affects the brain
• Pulmonary edema, which affects the lungs
• Macular edema, which affects the eyes

Treatment of edema

When the underlying cause of edema is treated, the swelling usually clears up but a doctor may also recommend some measures that can be taken to decrease fluid retention such as losing weight, exercising regularly and avoiding standing for long periods. Diuretics or water pills may also be prescribed to help reduce fluid build-up.