Edema (or Oedema) is the abnormal accumulation of fluid in certain tissues within the body. The accumulation of fluid may be under the skin – usually in dependent areas such as the legs (peripheral edema, or ankle edema), or it may accumulate in the lungs (pulmonary edema). The location of edema can provide the health care practitioner the first clues in regard to the underlying cause of the fluid accumulation.
Causes of Edema
Edema is a normal response of the body to inflammation or injury. For example, a twisted ankle, a bee sting, or a skin infection will all result in edema in the involved area. In some cases, such as in an infection, this may be beneficial. Increased fluid from the blood vessels allows more infection-fighting white blood cells to enter the affected area.
Edema can also result from medical conditions or problems in the balance of substances normally present in blood. Some of the causes of edema include:
Low albumin (hypoalbuminemia): Albumin and other proteins in the blood act like sponges to keep fluid in the blood vessels. Low albumin may contribute to edema, but isn’t usually the sole cause.
Allergic reactions: Edema is a usual component of most allergic reactions. In response to the allergic exposure, the body allows nearby blood vessels to leak fluid into the affected area.
Obstruction of flow: If the drainage of fluid from a body part is blocked, fluid can back up. A blood clot in the deep veins of the leg can result in leg edema. A tumor blocking lymph or blood flow will cause edema in the affected area.
Critical illness: Burns, life-threatening infections, or other critical illnesses can cause a whole-body reaction that allows fluid to leak into tissues almost everywhere. Widespread edema throughout the body can result.
Edema and heart disease (congestive heart failure): When the heart weakens and pumps blood less effectively, fluid can slowly build up, creating leg edema. If fluid buildup occurs rapidly, fluid in the lungs (pulmonary edema) can develop. If there is heart failure of the right side of the heart, oftentimes edema can develop in the abdomen, as well.
Symptoms OF Edema
Signs and symptoms of edema include:
- Swelling or puffiness of the tissue directly under your skin
- Stretched or shiny skin
- Skin that retains a dimple after being pressed for several seconds
- Increased abdominal size
Fast facts on edema
Here are some key points about edema. More detail and supporting information is in the main article.
- Edema is caused by the retention of excess fluid within the body’s tissues.
- The symptoms of edema normally develop gradually over time.
- Approximately 4.4 million people in the US have developed edema.
- The three most common types of edema are peripheral, cerebral and eye edema.
- Swelling can result from capillaries leaking fluid into the surrounding tissue.
- The symptoms of edema mainly depend on what the underlying cause is.
- The cause of edema may be diagnosed by chest X-ray, blood tests, urine tests, liver function tests or heart function tests.
- Edema is normally caused by a more significant underlying disease or condition.
- A number of medications appear to cause pedal edema (foot edema).
- Lucentis (ranibizumab injection) is an FDA-approved treatment for diabetic macular edema.
Self Care at Home
Compression stockings can be helpful by increasing the resistance to fluid leaking out of the vessels. These can be purchased in any medical supply store, and are particularly useful for peripheral edema. Body positioning can also be helpful for both peripheral and pulmonary edema to ease symptoms. For example, elevating the head with pillows in bed may benefit someone with pulmonary edema, while elevating the legs may minimize ankle and/or leg edema.
Once again, the treatment depends on the condition causing edema. In general, the treating principle is to reverse the forces that are not working properly:
- Increase the forces that keep fluid inside the blood vessels
- Reduce the forces that cause fluid to leak out of the blood vessels
- Identify the cause of the leaking blood vessel walls
For example, increasing the blood protein (albumin) level in a patient with a nutritional deficiency can help retain fluid in the blood vessels. Healing tissues exposed to trauma, (for example, swelling from a sprained ankle) assists in preventing fluid leaking from blood vessels.
The ultimate goal with edema treatment is to rid the excess fluid that has accumulated in the surrounding tissues in the body. The most common treatment is a diuretic. Diuretics make the kidneys excrete excess fluid from the body; which reduces the general fluid volume in the body. Diuretics should be used with caution as dehydration can be a side effect. There are many different types of diuretics that have different mechanisms of action and different potencies.