Edema, also spelled oedema or œdema, is an abnormal accumulation of fluid in the interstitium, located beneath the skin and in the cavities of the body, which can cause severe pain. Clinically, hyperaldosteronism, edema manifests as swelling. The amount of interstitial fluid is determined by the balance of fluid homeostasis and the increased secretion of fluid into the interstitium. The word is from Greek οἴδημα oídēma meaning "swelling".[1] The condition is also known (mostly archaic) as dropsy.

Other namesOedema, dropsy, hydropsy
"Pitting" edema
  • /ɪˈdiːmə/
SpecialtyCardiology, nephrology


Cutaneous edema is referred to as "pitting" when, after pressure is applied to a small area, the indentation persists after the release of the pressure. Peripheral pitting edema, as shown in the illustration, is the more common type, resulting from water retention. It can be caused by systemic diseases, pregnancy in some women, either directly or as a result of heart failure, or local conditions such as varicose veins, thrombophlebitis, insect bites, and dermatitis.

Non-pitting edema is observed when the indentation does not persist. It is associated with such conditions as lymphedema, lipedema, and myxedema.

Edema caused by malnutrition defines kwashiorkor, an acute form of childhood protein-energy malnutrition characterized by edema, irritability, anorexia, ulcerating dermatoses, and an enlarged liver with fatty infiltrates.


Grading of edema[2]
Grade Definition
Absent Absent
Grade + Mild: Both feet / ankles
Grade ++ Moderate: Both feet,
plus lower legs,
hands or lower arms
Grade +++ Severe: Generalised
bilateral pitting edema,
including both feet,
legs, arms and face

A rise in hydrostatic pressure occurs in cardiac failure. A fall in osmotic pressure occurs in nephrotic syndrome and liver failure.[3]

Causes of edema which are generalized to the whole body can cause edema in multiple organs and peripherally. For example, severe heart failure can cause pulmonary edema, pleural effusions, ascites and peripheral edema. Such severe systemic edema is called anasarca. In rare cases, a Parvovirus B19 infection may cause generalized edemas.[4]

Although a low plasma oncotic pressure is widely cited for the edema of nephrotic syndrome, most physicians note that the edema may occur before there is any significant protein in the urine (proteinuria) or fall in plasma protein level. Most forms of nephrotic syndrome are due to biochemical and structural changes in the basement membrane of capillaries in the kidney glomeruli, and these changes occur, if to a lesser degree, in the vessels of most other tissues of the body. Thus the resulting increase in permeability that leads to protein in the urine can explain the edema if all other vessels are more permeable as well.[5]

As well as the previously mentioned conditions, edemas often occur during the late stages of pregnancy in some women. This is more common with those of a history of pulmonary problems or poor circulation also being intensified if arthritis is already present in that particular woman. Women that already have arthritic problems most often have to seek medical help for pain caused from over-reactive swelling. Edemas that occur during pregnancy are usually found in the lower part of the leg, usually from the calf down.


An edema will occur in specific organs as part of inflammations, tendonitis or pancreatitis, for instance. Certain organs develop edema through tissue specific mechanisms.

Examples of edema in specific organs:

  • Pedal edema (dependent edema of legs) is extracellular fluid accumulation in the legs. This can occur in otherwise healthy people due to hypervolemia or maintaining a standing or seated posture for an extended period of time. It can occur due to diminished venous return of blood to the heart due to congestive heart failure or pulmonary hypertension. It can also occur in patients with increased hydrostatic venous pressure or decreased oncotic venous pressure, due to obstruction of lymphatic or venous vessels draining the lower extremity. Certain drugs (for example, amlodipine) can cause pedal edema.
  • Cerebral edema is extracellular fluid accumulation in the brain. It can occur in toxic or abnormal metabolic states and conditions such as systemic lupus or reduced oxygen at high altitudes. It causes drowsiness or loss of consciousness, leading to brain herniation and death.
  • Pulmonary edema occurs when the pressure in blood vessels in the lung is raised because of obstruction to the removal of blood via the pulmonary veins. This is usually due to failure of the left ventricle of the heart. It can also occur in altitude sickness or on inhalation of toxic chemicals. Pulmonary edema produces shortness of breath. Pleural effusions may occur when fluid also accumulates in the pleural cavity.
  • Edema may also be found in the cornea of the eye with glaucoma, severe conjunctivitis or keratitis or after surgery. Sufferers may perceive coloured haloes around bright lights.
  • Edema surrounding the eyes is called periorbital edema or eye puffiness. The periorbital tissues are most noticeably swollen immediately after waking, perhaps as a result of the gravitational redistribution of fluid in the horizontal position.
  • Another cutaneous form of edema is myxedema, which is caused by increased deposition of connective tissue. In myxedema (and a variety of other rarer conditions) edema is caused by an increased tendency of the tissue to hold water within its extracellular space. In myxedema this is because of an increase in hydrophilic carbohydrate-rich molecules (perhaps mostly hyaluronin) deposited in the tissue matrix. Edema forms more easily in dependent areas in the elderly (sitting in chairs at home or on aeroplanes) and this is not well understood. Estrogens alter body weight in part through changes in tissue water content. There may be a variety of poorly understood situations in which transfer of water from tissue matrix to lymphatics is impaired because of changes in the hydrophilicity of the tissue or failure of the 'wicking' function of terminal lymphatic capillaries.
  • In lymphedema abnormal removal of interstitial fluid is caused by failure of the lymphatic system. This may be due to obstruction from, for example, pressure from a cancer or enlarged lymph nodes, destruction of lymph vessels by radiotherapy, or infiltration of the lymphatics by infection (such as elephantiasis). It is most commonly due to a failure of the pumping action of muscles due to immobility, most strikingly in conditions such as multiple sclerosis, or paraplegia. It has been suggested that the edema that occurs in some people following use of aspirin-like cyclo-oxygenase inhibitors such as ibuprofen or indomethacin may be due to inhibition of lymph heart action.
  • Hydrops fetalis is a condition of the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments.


Six factors can contribute to the formation of edema:

  1. increased hydrostatic pressure;
  2. reduced colloidal or oncotic pressure within blood vessels;
  3. increased tissue colloidal or oncotic pressure;
  4. increased blood vessel wall permeability (e.g., inflammation);
  5. obstruction of fluid clearance in the lymphatic system;
  6. changes in the water retaining properties of the tissues themselves. Raised hydrostatic pressure often reflects retention of water and sodium by the kidneys.[7]

Generation of interstitial fluid is regulated by the forces of the Starling equation.[8] Hydrostatic pressure within blood vessels tends to cause water to filter out into the tissue. This leads to a difference in protein concentration between blood plasma and tissue. As a result, the colloidal or oncotic pressure of the higher level of protein in the plasma tends to draw water back into the blood vessels from the tissue. Starling's equation states that the rate of leakage of fluid is determined by the difference between the two forces and also by the permeability of the vessel wall to water, which determines the rate of flow for a given force imbalance. Most water leakage occurs in capillaries or post capillary venules, which have a semi-permeable membrane wall that allows water to pass more freely than protein. (The protein is said to be reflected and the efficiency of reflection is given by a reflection constant of up to 1.) If the gaps between the cells of the vessel wall open up then permeability to water is increased first, but as the gaps increase in size permeability to protein also increases with a fall in reflection coefficient.

Changes in the variables in Starling's equation can contribute to the formation of edemas either by an increase in hydrostatic pressure within the blood vessel, a decrease in the oncotic pressure within the blood vessel or an increase in vessel wall permeability. The latter has two effects. It allows water to flow more freely and it reduces the colloidal or oncotic pressure difference by allowing protein to leave the vessel more easily.


Case 11-leftN
Vein obstruction causes facial edema while lying down to sleep.
Case 11-rightN
After being upright all day, the swelling disappears.

When possible, treatment involves resolving the underlying cause.

Treatment may also involve positioning the affected body parts to improve drainage. For example, swelling in feet or ankles may be reduced by having the person lie down in bed or sit with the feet propped up on cushions. Intermittent pneumatic compression can be used to pressurize tissue in a limb, forcing fluids—both blood and lymph—to flow out of the pressurized area.


Geschwollener menschlicher Fuß

Foot, c. 2 weeks post-surgery because of compartment syndrome


Left and right ring fingers of the same individual. The distal phalanx of the finger on the right exhibits edema due to acute paronychia.

See also


  1. ^ οἴδημα, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
  2. ^ Nutrition in Emergencies > Measuring œdema. Erin Boyd, reviewed by Diane Holland, Nutrition in Emergencies Unit, UNICEF. Retrieved Nov 2012
  3. ^ Renkin EM (1994). "Cellular aspects of transvascular exchange: a 40-year perspective". Microcirculation. 1 (3): 157–67. doi:10.3109/10739689409148270. PMID 8790586.
  4. ^ Wiggli B, Imhof E, Meier CA, Laifer G (2013). "Water, water, everywhere. Acute parvovirus B19 infection". Lancet. 381 (9868): 776. doi:10.1016/S0140-6736(12)61894-7. PMID 23472922.
  5. ^ Palmer BF, Alpern RJ (1997). "Pathogenesis of edema formation in the nephrotic syndrome". Kidney Int. Suppl. 59: S21–7. PMID 9185099.
  6. ^ C.Michael Hogan (2008) "Western poison-oak: Toxicodendron diversilobum" Archived July 21, 2009, at the Wayback Machine, GlobalTwitcher, ed. Nicklas Strömberg
  7. ^ Kumar; Abbas; Fausto (1999). Pathologic Basis of Disease (7th ed.). Elsevier Saunders. p. 122. ISBN 0-7216-0187-1.
  8. ^ Boron W.F., Boulpaep E.L. (2012.) Medical Physiology: A Cellular and Molecular Approach, 2e. Saunders/Elsevier, Philadelphia, PA.

External links

External resources
Acne with facial edema

Acne with facial edema occurs uncommonly, and is associated with a peculiar inflammatory edema of the mid-third of the face.

Altitude sickness

Altitude sickness, the mildest form being acute mountain sickness (AMS), is the negative health effect of high altitude, caused by rapid exposure to low amounts of oxygen at high elevation. Symptoms may include headaches, vomiting, tiredness, trouble sleeping, and dizziness. Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) with associated shortness of breath or high altitude cerebral edema (HACE) with associated confusion. Chronic mountain sickness may occur after long term exposure to high altitude.Altitude sickness typically occurs only above 2,500 metres (8,000 ft), though some are affected at lower altitudes. Risk factors include a prior episode of altitude sickness, a high degree of activity, and a rapid increase in elevation. Diagnosis is based on symptoms and is supported in those who have more than a minor reduction in activities. It is recommended that at high-altitude any symptoms of headache, nausea, shortness of breath, or vomiting be assumed to be altitude sickness.Prevention is by gradually increasing elevation by no more than 300 metres (1,000 ft) per day. Being physically fit does not decrease the risk. Treatment is generally by descending to a lower altitude and sufficient fluids. Mild cases may be helped by ibuprofen, acetazolamide, or dexamethasone. Severe cases may benefit from oxygen therapy and a portable hyperbaric bag may be used if descent is not possible. Treatment efforts, however, have not been well studied.AMS occurs in about 20% of people after rapidly going to 2,500 metres (8,000 ft) and 40% of people going to 3,000 metres (10,000 ft). While AMS and HACE occurs equally frequently in males and females, HAPE occurs more often in males. The earliest description of altitude sickness is attributed to a Chinese text from around 30 BCE which describes "Big Headache Mountains" possibly referring to the Karakoram Mountains around Kilik Pass.


Angioedema is an area of swelling of the lower layer of skin and tissue just under the skin or mucous membranes. The swelling may occur in the face, tongue, larynx, abdomen, or arms and legs. Often it is associated with hives, which are swelling within the upper skin. Onset is typically over minutes to hours.The underlying mechanism typically involves histamine or bradykinin. The version related to histamine is due to an allergic reaction to agents such as insect bites, foods, or medications. The version related to bradykinin may occur due to an inherited problem known as C1 esterase inhibitor deficiency, medications known as angiotensin converting enzyme inhibitors, or a lymphoproliferative disorder.Efforts to protect the airway may include intubation or cricothyroidotomy. Histamine-related angioedema can be treated with antihistamines, corticosteroids, and epinephrine. In those with bradykinin-related disease a C1 esterase inhibitor, ecallantide, or icatibant may be used. Fresh frozen plasma may be used instead. In the United States the disease affects about 100,000 people a year.


Arterivirus is the former genus of viruses in the family Arteriviridae, which is within the order Nidovirales. Vertebrates serve as natural hosts. There are currently four species in this genus including the type species Equine arteritis virus. Diseases associated with this genus include: EAV: vascular lesions, fever, edema, abortion. PRRSV: abortions and respiratory disease. SHFV: fever, edema, dehydration, hemorragies, death (almost 100%).

Cerebral edema

Cerebral edema is excess accumulation of fluid (edema) in the intracellular or extracellular spaces of the brain.

Diabetic retinopathy

Diabetic retinopathy, also known as diabetic eye disease, is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness.Diabetic retinopathy affects up to 80 percent of those who have had diabetes for 20 years or more. At least 90% of new cases could be reduced with proper treatment and monitoring of the eyes. The longer a person has diabetes, the higher his or her chances of developing diabetic retinopathy. Each year in the United States, diabetic retinopathy accounts for 12% of all new cases of blindness. It is also the leading cause of blindness in people aged 20 to 64.

High-altitude pulmonary edema

High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema (fluid accumulation in the lungs) that occurs in otherwise healthy mountaineers at altitudes typically above 2,500 meters (8,200 ft). However, cases have also been reported at lower altitudes (between 1,500–2,500 metres or 4,900–8,200 feet) in highly vulnerable subjects.

Classically, HAPE occurs in persons normally living at low altitude who travel or ascend to an altitude above 2,500 meters (8,200 feet). Re-entry HAPE is also an entity that has been described in persons who normally live at high altitude but who develop pulmonary edema after returning from a stay at low altitude.There are many factors that can make a person more susceptible to developing HAPE, including genetic factors, but detailed understanding is lacking and currently under investigation. HAPE remains the major cause of death related to high-altitude exposure, with a high mortality rate in the absence of adequate emergency treatment.

Jon Brower Minnoch

Jon Brower Minnoch (September 29, 1941 – September 10, 1983) was an American man who, at his peak weight, was the heaviest human being ever recorded, weighing approximately 1,400 lb (635 kilograms; 100 stone). This figure was only a close estimation because his extreme size, declining health, and lack of mobility prevented use of a scale.


Kwashiorkor is a form of severe protein malnutrition characterized by edema, and an enlarged liver with fatty infiltrates. Sufficient calorie intake, but with insufficient protein consumption, distinguishes it from marasmus. Kwashiorkor cases occur in areas of famine or poor food supply. Cases in the developed world are rare.Jamaican pediatrician Cicely Williams introduced the name into the medical community in a 1935 Lancet article, two years after she published the disease's first formal description in the Western medical literature. The name is derived from the Ga language of coastal Ghana, translated as "the sickness the baby gets when the new baby comes" or "the disease of the deposed child", and reflecting the development of the condition in an older child who has been weaned from the breast when a younger sibling comes. Breast milk contains amino acids vital to a child's growth. In at-risk populations, kwashiorkor may develop after a mother weans her child from breast milk, replacing it with a diet high in carbohydrates, especially sugar.


Lymphedema, also known as lymphoedema and lymphatic edema, is a condition of localized fluid retention and tissue swelling caused by a compromised lymphatic system. The lymphatic system functions as a critical portion of the body's immune system and returns interstitial fluid to the bloodstream. Lymphedema is most frequently a complication of cancer treatment or parasitic infections, but it can also be seen in a number of genetic disorders. Though incurable and progressive, a number of treatments can ameliorate symptoms. Tissues with lymphedema are at high risk of infection because the lymphatic system has been compromised.

Macular edema

Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye (a yellow central area of the retina) and causes it to thicken and swell (edema). The swelling may distort a person's central vision, because the macula holds tightly packed cones that provide sharp, clear, central vision to enable a person to see detail, form, and color that is directly in the centre of the field of view.

Milroy's disease

Milroy's disease (MD) is a familial disease characterized by lymphedema, commonly in the legs, caused by congenital abnormalities in the lymphatic system. Disruption of the normal drainage of lymph leads to fluid accumulation and hypertrophy of soft tissues.It was named by Sir William Osler for William Milroy, a Canadian physician, who described a case in 1892, though it was first described by Rudolf Virchow in 1863.

Nephrotic syndrome

Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes protein in the urine, low blood albumin levels, high blood lipids, and significant swelling. Other symptoms may include weight gain, feeling tired, and foamy urine. Complications may include blood clots, infections, and high blood pressure.Causes include a number of kidney diseases such as focal segmental glomerulosclerosis, membranous nephropathy, and minimal change disease. It may also occur as a complication of diabetes or lupus. The underlying mechanism typically involves damage to the glomeruli of the kidney. Diagnosis is typically based on urine testing and sometimes a kidney biopsy. It differs from nephritic syndrome in that there are no red blood cells in the urine.Treatment is directed at the underlying cause. Other efforts include managing high blood pressure, high blood cholesterol, and infection risk. A low salt diet and limiting fluids is often recommended. About 5 per 100,000 people are affected per year. The usual underlying cause varies between children and adults.

Peripheral edema

Peripheral edema is edema (accumulation of fluid causing swelling) in tissues perfused by the peripheral vascular system, usually in the lower limbs. In the most dependent parts of the body (those hanging distally), it may be called dependent edema.

The condition is commonly associated with aging, but can be caused by many other conditions, including congestive heart failure, renal failure, liver cirrhosis, portal hypertension, trauma, alcoholism, altitude sickness, pregnancy, hypertension, sickle cell anemia, compromised lymphatic system, or merely long periods of time sitting or standing without moving. Some medicines (e.g. amlodipine, pregabalin) may also cause or worsen the condition.There was case reported that spinal manipulation may change lympthatic return via autonomic nervous system, which may have help alleviating oedema.

Persistent edema of rosacea

Persistent edema of rosacea (also known as "Chronic upper facial erythematous edema," "Morbihan's disease," or "Rosaceous lymphedema") is a hard, nonpitting edema found on the areas involved, those mainly being the forehead, glabella, upper eyelids, nose, and/or cheeks.

Pulmonary edema

Pulmonary edema is fluid accumulation in the tissue and air spaces of the lungs. It leads to impaired gas exchange and may cause respiratory failure. It is due to either failure of the left ventricle of the heart to remove blood adequately from the pulmonary circulation (cardiogenic pulmonary edema), or an injury to the lung parenchyma or vasculature of the lung (non-cardiogenic pulmonary edema). Treatment is focused on three aspects: firstly improving respiratory function, secondly, treating the underlying cause, and thirdly avoiding further damage to the lung. Pulmonary edema, especially acute, can lead to fatal respiratory distress or cardiac arrest due to hypoxia. It is a cardinal feature of congestive heart failure. The term edema is from the Greek οἴδημα (oídēma, "swelling"), from οἰδέω (oidéō, "I swell").

Superior vena cava syndrome

Superior vena cava syndrome (SVCS), is a group of symptoms caused by obstruction of the superior vena cava ("SVC"), a short, wide vessel carrying circulating blood into the heart. The majority of cases are caused by malignant tumors within the mediastinum, most commonly lung cancer and non-Hodgkin's lymphoma, directly compressing or invading the SVC wall. Non-malignant causes are increasing in prevalence due to expanding use of intravascular devices (such as permanent central venous catheters and leads for pacemakers and defibrillators), which can result in thrombosis. Other non-malignant causes include benign mediastinal tumors, aortic aneurysm, infections, and fibrosing mediastinitis.Characteristic features are edema (swelling due to excess fluid) of the face and arms and development of swollen collateral veins on the front of the chest wall. Shortness of breath and coughing are quite common symptoms; difficulty swallowing is reported in 11% of cases, headache in 6% and stridor (a high-pitched wheeze) in 4%. The symptoms are rarely life-threatening, though edema of the epiglottis can make breathing difficult, edema of the brain can cause reduced alertness, and in less than 5% of cases of SVCO, severe neurological symptoms or airway compromise are reported. Resolution of superior vena cava syndrome is directly related to the treatment of the underlying compression.

Swelling (medical)

Swelling is a transient abnormal enlargement of a body part or area caused not by neoplasm (proliferation of cells) but by accumulation of interstitial fluid (fluid in tissues). It can occur throughout the body (generalized), or it can affect a specific part or organ (localized). Swelling is usually not dangerous and is a common reaction to an inflammation or a bruise.

Swelling is considered one of the five characteristics of inflammation; along with pain, heat, redness, and loss of function.

A body part may swell in response to injury, infection, or disease. Swelling, especially of the ankle, can occur if the body is not circulating fluid well. If water retention progresses to a symptomatic extent, swelling results.

Generalized swelling, or massive edema (also called anasarca), is a common sign in severely ill people. Although slight edema may be difficult to detect to the untrained eye, especially in an overweight person, massive edema is very obvious.

Swimming-induced pulmonary edema

Swimming induced pulmonary edema (SIPE), also known as immersion pulmonary edema, occurs when fluids from the blood leak abnormally from the small vessels of the lung (pulmonary capillaries) into the airspaces (alveoli).SIPE usually occurs during exertion in conditions of water immersion, such as swimming and diving. With the recent surge in popularity of triathlons and swimming in open water events there has been an increasing incidence of SIPE. It has been reported in scuba divers, apnea (breath hold) free-diving competitors combat swimmers, and triathletes. The causes are incompletely understood at the present time.

Disturbances of
skin sensation
Disorders of blood flow

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.