edema

and Sabine Schrör, medical journalist

Hanna Rutkowski is a freelance writer for the medical team.

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Sabine Schrör is a freelance writer for the medical team. She studied business administration and public relations in Cologne. As a freelance editor, she has been at home in a wide variety of industries for more than 15 years. Health is one of her favorite subjects.

More about the experts All content is checked by medical journalists.

Edema is swelling caused by fluid retention. Edema can develop all over the body or be regionally limited. Edema of the legs and ankles is particularly common, for example when it is hot or after long periods of standing. Serious illnesses can also be accompanied by swelling, such as heart failure or kidney disease. Read more about the causes, diagnosis and treatment of edema!

Brief overview

What is edema? Swelling due to fluid stored in the tissue
How does edema develop? Due to overpressure in the smallest blood or lymph vessels, which causes fluid to escape into the surrounding tissue
Classification according to various criteria: e.g. generalized and regional edema, perifocal edema, special forms (such as lymphedema, Quincke's edema)
Causes: Often harmless (e.g. long standing or sitting, heat, pregnancy), but sometimes serious, e.g. heart, kidney or liver diseases, circulatory disorders, weak veins, thrombosis, allergies, inflammation
When to the doctor When the affected part of the body becomes unnaturally warm or cold and turns bluish or reddish in color; with further symptoms such as pain, fever, shortness of breath, clouding of consciousness; with sudden onset or rapid increase in edema
Examination: taking the medical history (anamnesis), physical examination, blood test, ultrasound if necessary
Treatment: Treatment of the underlying disease, possibly water tablets (diuretics)
Prevention: If the cause is harmless, exercise, elevate the legs and warm-cold alternating baths; Sometimes a low-salt and dehydrating diet is helpful

Edema: description

With edema, fluid collects in the tissues, causing visible swelling. This is often a sign that the body's own fluid balance is no longer functioning properly.

Impaired fluid balance

Our body mainly consists of fluid that is distributed in the cells, the interstitial spaces, the connective tissue and the subcutaneous tissue. Even our bones contain water. And blood, too, consists mainly of water with many different types of cells floating in it.

Several liters of fluid pass into the interstitium from the smallest veins (capillaries) every day. From there, the greater part gets back into the bloodstream, where veins transport it back to the heart. About ten percent of the interstitial fluid, on the other hand, drains through the lymphatic system. If the pressure inside the veins increases, more fluid is pressed into the surrounding tissue. This in turn reduces the pressure in the vessels.

Regulation of the water balance

Special pressure sensors (baroreceptors) in the carotid artery and in the aorta regularly measure the pressure in the circulation. If the values are too low, an increase in blood pressure is initiated: the arteries constrict and the heart pumps stronger and faster. This mechanism allows the body to adjust the blood pressure in the short term.

For a longer-term effect, the body turns the water balance. Special sensors, the so-called volume receptors of the heart, are used for this. They work together with the pressure receptors. If there is too little fluid in the circulation and the pressure is low, special hormones are released through two reflexes - based on the volume receptors. As a result, the kidneys excrete less fluid.

Vicious circle of protein deficiency

But sometimes that leads to a vicious circle. In some diseases, for example, important proteins are missing in the blood. They usually hold the water in the vascular system. If they are missing, the fluid passes more easily into the tissue and, conversely, is no longer properly absorbed. An edema develops. This also means that there is no water in the circuit, which the sensors quickly recognize. As a result, the body excretes less water. However, because the proteins are still missing, the retained fluid quickly passes back into the tissue - the edema increases, whereas there is still a lack of water in the bloodstream.

Classification of edema

Edema therefore occurs when the flow of blood through the capillaries changes. Depending on what the reason for this is, a distinction is made:

Hydrostatic edema: It occurs because the pressure inside the vessels (hydrostatic pressure) is increased, so that more fluid is pressed into the surrounding tissue.
Colloid osmotic edema: A lack of protein in the blood causes the colloid osmotic (oncotic) pressure to drop, causing more fluid to collect in the tissue and causing edema.
Inflammatory edema: As a result of inflammatory processes, but also allergies or burns, the vessel walls become more permeable, so that more fluid escapes from the blood into the tissue.
Mechanical edema: The fluid builds up in the tissue due to disorders of the lymphatic drainage.

Edema can, however, also be classified according to criteria other than the mechanism by which it develops. For example, according to the location of the swelling:

Generalized edema occurs all over the body (e.g. hormone-related water retention in women before the menstrual period as part of the premenstrual syndrome),
Regionalized (regional) edema only affects one region of the body (e.g. on a lower leg after a thrombosis).
Perifocal edema forms in healthy tissue around a focus of the disease (in the case of tumors, abscesses or radiation)
Intracellular edema develops in a cell and causes it to swell.
Extracellular edema is located in the intercellular space.

Another classification criterion is the course of an edema:

Acute edema (e.g. with acute heart failure, kidney failure, inflammation, burns, thrombosis)
Chronic edema (e.g. in cirrhosis of the liver, chronic venous insufficiency)

There are also special forms of edema such as lymphedema and Quincke's edema.

Lymphedema

In the case of lymphedema (lymphedema), lymph fluid builds up in the lymph vessels: the lymph is not properly transported away, it also escapes into the surrounding tissue and causes it to swell. Sometimes the reason for this is congenital - the lymphatic system has a malformation.

Acquired (secondary) lymphedema is much more common: it develops over the course of life, mostly due to cancer or as a result of radiation or surgery on the tumor.

You can find detailed information about this particular form of edema in the article Lymphedema.

Quincke's edema

Quincke's edema (angioedema) is an acute swelling of the leather skin (dermis) and subcutaneous tissue (subcutis) or the mucous membrane with the underlying connective tissue layer (submucosa). It usually forms on the face, around the eyelids and lips, on the mucous membranes of the pharynx, on the epiglottis and on the tongue.

Sometimes Quincke's edema is congenital. But it can also be acquired. Then it usually occurs as part of an allergic reaction, for example in allergic hives (urticaria). The angioedema is also often painful or burning.

Quincke's edema can be life-threatening if it affects the mucous membrane of the throat or the larynx, causing acute shortness of breath!

Edema: causes

Many edema are due to harmless causes. One-sided stress (sitting or standing for long periods of time) can lead to edema in the legs and / or feet. This happens as follows: through the veins, oxygen-poor blood is transported from the organism back to the heart. The blood overcomes gravity with the help of the muscles that tense when you move. Blood that has to flow from the leg veins back to the heart has a particularly long way to travel. If the so-called muscle pump fails due to physical inactivity, the blood sinks into the legs - thick legs and feet are the result. If hot summer temperatures are added, the legs and / or feet swell even more.

Edema also often develops in pregnant women, especially in the last few weeks before giving birth. Hormonally induced changes in the water balance and the quality of the connective tissue as well as increased pressure on the large veins in the abdomen and the resulting disturbed drainage can lead to water retention in the tissue.

Edema all over the body

But there can also be more serious reasons for edema. Generalized edema can occur, for example, in:

Heart disease: swollen legs are often the result of a weak heart, especially of the right heart (right heart failure).
Kidney diseases such as nephrotic syndrome, inflamed kidney corpuscles (glomerulonephritis), kidney weakness up to kidney failure can cause a protein deficiency or an unbalanced electrolyte balance with water retention in the legs.

Liver diseases: The liver usually produces too few proteins and the colloid-osmotic pressure in the vascular system falls. Water retention in the abdomen (ascites, ascites) often occurs in liver cancer or liver metastases, liver cirrhosis and liver weakness.
Underactive thyroid (hypothyroidism): In severe cases, swelling of the legs, arms and face (myxedema) forms. Strictly speaking, however, mainly glycosaminoglycans, special carbohydrates, are stored here because their metabolism is disturbed in hypothyroidism.
Adrenal diseases often lead to impaired production of the hormone aldosterone, which leads to water retention in the abdomen and legs.
Malnutrition: A sign of a long period of hunger is the "hunger stomach" caused by a lack of protein.
Medication: Antidepressants, high blood pressure medication, glucocorticoids ("cortisone"), and anti-inflammatory drugs can also cause edema.

Edema in a specific area of the body

Regional edema is mainly caused by:

Disorders of the lymphatic drainage: The tissue fluid is transferred back to the venous vessels via the lymphatic system. Congenital or mechanical disorders (external pressure, bruises) disrupt the lymphatic drainage and thus cause swelling in the tissue. Causes for this are, for example, tumors, operations and radiation. But also the infestation with parasitic roundworms of the filariasis can cause an extreme form of the edema, the elephantiasis.

Circulatory disorders can affect veins or arteries and, in addition to edema, also trigger an undersupply of the tissue.
Chronic venous insufficiency (CVI): Damaged venous valves in particular prevent the blood from flowing back to the heart. Instead, it builds up, especially in the legs, due to gravity. This can lead to excessive water retention.
Thrombosis: The closure of a vessel by a blood clot (thrombus) massively impedes the flow of blood. The leg veins are often affected - typical signs are pain, edema and a bluish discoloration of the skin.
Inflammations, burns and injuries: The vessel walls can become more permeable, which promotes water retention in the surrounding tissue.

Allergies: Contact with an allergy trigger (allergen) calls up immune cells, whose messenger substances make the vessel walls more permeable. Then more fluid flows from the vessels into the tissue and causes swelling there. This can also lead to Quincke's edema (see above).
Hereditary angioedema (HAE): The hereditary special form of Quincke's edema manifests itself in acute and sudden swelling, especially on the extremities, but also in the area of the abdominal organs. The occurrence of this swelling is unpredictable.

Edema: examinations

Many edema go away on their own. This applies in particular to water retention after long periods of standing or sitting, as well as swelling of the eyelids as a result of an allergic reaction. Then, in general, no medical examinations are necessary. However, there are situations in which you should definitely see a doctor.

Edema: when to see a doctor?

It can be dangerous if allergic edema affects the airways, for example in the case of severe food allergies (such as a peanut allergy). Water retention in the abdomen is also mostly due to a serious cause and should always be clarified by a doctor. You can recognize ascites when the stomach becomes thicker and plumper without changing your eating habits and the weight on the scales increases inexplicably for you.

In general, you should see a doctor if you have:

The edema developed quickly and on one side only
The edema does not go away on its own or gets bigger
The swelling is also warm, red, or painful
The affected part of the body becomes unnaturally warm or cold and turns bluish or reddish in color
If you have a fever
If you are short of breath
With clouding of consciousness up to delirium

Medical examinations

The doctor will first ask you about your medical history (anamnesis). The following information is particularly important:

When did the edema develop?
How does it express itself (pain, spread, course)?
What medications are you taking?
Do you suffer from previous illnesses or allergies?
Do you also have difficulty breathing?
Do you have to urinate more often at night? (The reason: when lying down, the water from the edema flows more easily back to the heart, from where it is pumped to the kidneys and excreted)

The next step is a physical exam. The edema itself is usually easy to spot. Its location gives the doctor the first clues to find the cause. For example, swollen legs are more likely to be found in heart failure, thrombosis or venous disease, while water retention in the abdomen (ascites) often indicates liver damage.

When palpating, the doctor checks whether the edema can be indented. To do this, he applies pressure to the swelling with his finger. If an imprint remains visible, it is a water-rich edema. Lymphedema in the advanced stage, on the other hand, cannot be “pushed away”.

Blood tests show whether there is a protein deficiency or blood salt disorders. In addition, the urine can be checked for protein (proteinuria) - in kidney disease, the body typically loses protein in the urine.

Sometimes imaging techniques are also used. Ascites, for example, can be detected by means of an ultrasound examination. It allows an assessment of how much water has stored in the abdominal cavity and whether the cause can possibly be found in the liver. The leg veins and possible thromboses can also be made clearly visible with the help of ultrasound.

Edema: treatment

Edema treatment depends on the cause. In the case of weak veins, for example, compression stockings help against the edema. They are also used in a thrombosis as soon as the edema has subsided (until then a compression bandage is wrapped). In addition, thrombosis patients receive anti-coagulation medication (anticoagulation).

Sometimes the doctor has to prescribe draining medication (diuretics), for example in the case of edema caused by the heart or kidneys. The right dosage of medication and an appropriate fluid intake are important. It is important to find a balance between fluid intake and excretion and avoid the loss of important salts.

Different groups of active substances can be distinguished among diuretics:

Loop diuretics such as furosemide or torasemide are effective, but also remove salts such as potassium and sodium.
Potassium-sparing diuretics such as spironolactone are used in particular for ascites with liver damage or in patients with cardiac insufficiency.
Thiazide diuretics are often concomitant drugs in antihypertensive therapies, but they also disrupt the blood salt balance (sodium (!), Potassium, magnesium)

Edema: you can do that yourself

If it is normal, harmless water retention, you can gently remedy the situation yourself with a few tips. However, if you suffer from a disease, such as heart or kidney disease, be sure to talk to your doctor before using the tips.

Movement: Active leg muscles act as "muscle pumps" and ensure that the water is transported back to the heart via the bloodstream.
Drainage Teas: Some plants are said to aid in draining the body. Nettle tea or green tea, for example, are very suitable. Tea made from St. John's wort also has a dehydrating effect, but is not suitable for women who use birth control pills.
Dehydrating foods: Some foods are also said to have a dehydrating effect. These include rice and potatoes in particular. Pineapple, strawberries, fennel and lettuce also drive fluids out of the body.
Little salt: Avoid using salt as much as possible when cooking. Alternatively, dishes can often be seasoned with herbs. In addition, do not eat salty foods such as ready meals and salty snacks (e.g. salted peanuts).
Put your legs up: Just lying up helps against swollen legs.
Circulation-promoting measures: Kneipp baths with alternating warm and cold water keep blood vessels and muscles healthy. The blood flow in the feet increases, the veins pump more blood back to the heart and the tendency to edema decreases. You can read more about this in the article hydrotherapy.

It remains important: If you keep getting edema or if it doesn't go away at all, talk to your doctor. This is the only way he can determine the cause and recommend suitable treatment for the edema.

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