Reviewed on 9/19/2022

What Things Should I Know About Edema?

Edema on the foot
Edema is the accumulation of fluid under the skin. Picture of edema in the foot by SPL/Science.

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 with the first clues in regard to the underlying cause of the fluid accumulation.

What Are the Signs and Symptoms of Edema? What Does It Look Like?

Symptoms will depend on the cause of edema.

Peripheral edema

Symptoms and signs of peripheral edema include swelling of the affected area(s), which causes the surrounding skin to "tighten." The swelling from peripheral edema is gravity-dependent (it will increase or decrease with changes in body position). For example, if a person is lying on their back (supine), the swelling will not appear in the legs but will appear in the area around the sacrum. The skin over the swollen area appears tight and shiny, and often when pressure is applied to the area with a finger, an indentation appears. This is called pitting edema.

Picture of pitted edema
Picture of pitted edema

Pulmonary Edema

In the case of pulmonary edema, there is often no evidence of fluid retention or noticeable swelling on examination of the patient's extremities. This is because the fluid is backing up into the lungs. Signs and symptoms of pulmonary edema include

  • shortness of breath,
  • difficulty breathing when lying flat,
  • waking up breathless, and
  • requiring multiple pillows to raise the head at night for a comfortable sleep.

What Causes Edema?

The balance and regulation of fluid in the body are very complex. In short, the cause of edema as simply defined as possible, is that tiny blood vessels in the body (capillaries) leak fluid into the surrounding tissues. This excess fluid causes the tissues to swell.

The cause of fluid leaking into the surrounding tissues may be the result of several mechanisms:

  1. Too much force or pressure inside the blood vessels
  2. A force outside of the blood vessel causes the fluid to be drawn through it.
  3. The wall of the blood vessel is compromised and cannot maintain equilibrium, leading to fluid loss.

Each of these three mechanisms may be associated with a variety of diseases or conditions. Examples include the following.

  • Pregnancy: Edema during pregnancy may occur because pregnant women have a greater volume of fluid circulating in the body and because they also retain more fluid. A woman may also experience postpartum edema.
  • Medications: Edema may be caused by a variety of medications, for example, steroids, calcium channel blockers (CCBs), thiazolidinediones, nonsteroidal anti-inflammatory drugs (NSAIDs), estrogens, etc.).
  • Liver disease and/or kidney disease: Both of these organs are vital in maintaining fluid balance in the body, and if severe disease is present in either of these organ systems, edema can develop. Examples include cirrhosis of the liver, chronic kidney disease, and acute kidney failure.
  • Venous insufficiency: This is a common condition in which blood does not return to the heart efficiently from the peripheral areas of the body (for example, the ankles, legs, feet, and hands), which results in edema. This typically results in edema in both legs.
  • Heart failure: If the heart is weak and cannot pump blood efficiently, blood will pool in particular areas of the body, which will cause fluid to leak from the blood vessels into the surrounding tissues.
    • If the right side of the heart is weak, pressure will build in the peripheral tissues in the body (hands, ankles, feet, legs). This is referred to as peripheral edema.
    • If the left side of the heart is weak, pressure will build in the lungs, causing pulmonary edema.
  • Idiopathic edema: Accumulation of fluid in surrounding tissues with no identifiable cause is referred to as idiopathic edema.

How Do Doctors Diagnose the Cause of Edema?

Depending on the details of the patient's history, the health care practitioner will perform a thorough examination. The health care practitioner may order tests, including a...

It is important to understand that while the edema itself can be physically limiting, ascertaining the underlying cause is important so that treatment can be targeted specifically to the condition causing edema. Sudden swelling of one or both legs may be a sign of a serious medical problem. If this occurs, see a health care practitioner immediately.

What Is the Medical Treatment for 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:

  1. Increase the forces that keep fluid inside the blood vessels
  2. Reduce the forces that cause fluid to leak out of the blood vessels
  3. 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 from leaking from blood vessels.

The ultimate goal of edema treatment is to rid the excess fluid that has accumulated in the surrounding tissues of 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.

Depending on the cause of edema, follow-up may be as easy as wearing support hose when standing for prolonged periods, or it may require the input of cardiologists, nephrologists, and/or other subspecialists. It is important to keep the primary physician abreast of any treatment.

What Home Remedies Treat and Help Relieve Edema?

  • 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.

Is It Possible to Prevent Edema?

  • Prevention of further episodes of edema can be achieved by the treatments mentioned above.
  • The ultimate goal is to address and treat any underlying cause of edema.

Is There a Cure for Edema?

  • With appropriate follow-up edema can be treated successfully.
  • The degree of response can vary depending on the severity of the cause and the patient's underlying medical condition.

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Pulmonary Edema Symptoms and Signs

Pulmonary edema is a condition in which an abnormal amount of fluid builds up in the lungs. Symptoms an signs of pulmonary edema include shortness of breath while lying flat, decrease in exercise tolerance, wheezing, and difficulty doing activities that were once routine.

Reviewed on 9/19/2022
Smith, C. Christopher. "Clinical manifestations and diagnosis of edema in adults." UpToDate. Mar. 4, 2021. <https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-edema-in-adults>.