Edema

"Dropsy" redirects here. For other uses, seedropsy (disambiguation)andedema (plants).

Edema
Other names	Oedema, œdema, fluid retention, water retention, dropsy, hydropsy, swelling
"Pitting" edema
Pronunciation	/ɪˈdiːmə/
Specialty	Cardiology,nephrology
Symptoms	Skin which feels tight, area may feel heavy
Usual onset	Sudden or gradual
Types	Generalized, localized
Causes	Venous insufficiency,heart failure,kidney problems,low protein levels,liver problems,deep vein thrombosis,lymphedema
Diagnostic method	Based on aphysical exam
Treatment	Based on cause

Edema(AmE), also spelledoedema(BrE), and also known asfluid retention,dropsy,hydropsyandswelling,is the build-up of fluid in the body'stissue.Most commonly, the legs or arms are affected.Symptoms may include skin that feels tight, the area feeling heavy, and joint stiffness.Other symptoms depend on the underlying cause.

Causes may includevenous insufficiency,heart failure,kidney problems,low protein levels,liver problems,deep vein thrombosis,infections,angioedema,certain medications, andlymphedema.It may also occur in immobile patients (stroke, spinal cord injury, aging), or with temporary immobility such as prolonged sitting or standing, and duringmenstruationorpregnancy.The condition is more concerning if it starts suddenly, or pain or shortness of breath is present.

Treatment depends on the underlying cause.If the underlying mechanism involvessodium retention,decreased salt intake and adiureticmay be used.Elevating the legs andsupport stockingsmay be useful for edema of the legs.Older people are more commonly affected.The word is from theGreekοἴδημαoídēmameaning 'swelling'.

Signs and symptoms

Specific area

An edema will occur in specific organs as part of inflammations,tendinitisorpancreatitis,for instance. Certain organs develop edema through tissue specific mechanisms. Examples of edema in specific organs:

• Peripheral edema( “dependent” edema of legs) is extracellular fluid accumulation in the lower extremities caused by the effects of gravity, and occurs when fluid pools in the lower parts of the body, including the feet, legs, or hands. This often occurs in immobile patients, such as paraplegics or quadriplegics, pregnant women, or in otherwise healthy people due tohypervolemiaor 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 edemais 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 tobrain herniationand death.
• Pulmonary edemaoccurs 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 effusionsmay occur when fluid also accumulates in thepleuralcavity.
• Edema may also be found in the cornea of the eye withglaucoma,severeconjunctivitis,keratitis,or after surgery. Affected people may perceive coloured haloes around bright lights.
• Edema surrounding the eyes is calledperiorbital edema(puffy eyes). The periorbital tissues are most noticeably swollen immediately after waking, perhaps as a result of the gravitational redistribution of fluid in the horizontal position.
• Common appearances ofcutaneousedema are observed withmosquitobites,spiderbites, bee stings (wheal and flare), and skin contact with certain plants such aspoison ivyorwestern poison oak,the latter of which are termedcontact dermatitis.
• Another cutaneous form of edema ismyxedema,which is caused by increased deposition ofconnective 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 due to an increase in hydrophilic carbohydrate-rich molecules (perhaps mostlyhyaluronin) 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.
• Myoedema is localized mounding of muscle tissue due to percussive pressure, such as flicking the relaxed muscle with the forefinger and thumb. It produces a mound, visible, firm and non-tender at the point of tactile stimulus approximately 1-2 seconds after stimulus, subsiding back to normal after 5-10 seconds. It is a sign in hypothyroid myopathy, such asHoffmann syndrome.
• Inlymphedema,abnormal removal of interstitial fluid is caused by failure of thelymphatic system.This may be due to obstruction from, for example, pressure from acanceror enlargedlymph nodes,destruction of lymph vessels byradiotherapy,or infiltration of the lymphatics by infection (such aselephantiasis). 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.

• 
  Foot two weeks post-surgery.
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  Thedistal phalanxof the right finger exhibits edema due toacute paronychia.
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  Severe edema in the legs and feet.

Generalized

A rise inhydrostatic pressureoccurs in cardiac failure. A fall in osmotic pressure occurs innephrotic syndromeandliver failure.

Causes of edema that are generalized to the whole body can cause edema in multiple organs and peripherally. For example, severe heart failure can causepulmonary edema,pleural effusions,ascitesandperipheral edema.Such severe systemic edema is calledanasarca.In rare cases, aparvovirus B19infection may cause generalized edemas.

Although a low plasmaoncotic pressureis 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.

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 who 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.

Hydrops fetalisis a condition in a baby characterized by an accumulation of fluid in at least two body compartments.

Cause

Heart

The pumping force of theheartshould help to keep a normal pressure within theblood vessels.But if the heart begins to fail (a condition known ascongestive heart failure) the pressure changes can cause very severe water retention. In this condition water retention is mostly visible in thelegs,feet andankles,but water also collects in thelungs,where it causes a chroniccough.This condition is usually treated withdiuretics;otherwise, the water retention may cause breathing problems and additional stress on the heart.

Kidneys

Another cause of severe water retention iskidney failure,where thekidneysare no longer able to filter fluid out of thebloodand turn it intourine.Kidney diseaseoften starts withinflammation,for instance in the case of diseases such asnephrotic syndromeorlupus.This type of water retention is usually visible in the form of swollenlegsandankles.

Liver

Cirrhosis(scarring) of the liver is a common cause of edema in the legs and abdominal cavity.

Veins

Phlebetic lymphedema (or phlebolymphedema) is seen in untreatedchronic venous insufficiencyand is the most common type of edema (approx. 90%).It is a combination venous/lymphatic disorder that originates in defective "leaky" veins that allows the blood to back flow (venous reflux), slowing the return of the blood to the heart (venous stasis). The venous pressure in the legs changes dramatically while standing compared to lying down. How much pressure there is depends on the person's height, in the average adult person, it is 8 mm Hg while lying down and 100 mm Hg while standing.

In venous insufficiency, venous stasis results in abnormally high venous pressure (venous hypertension) and greater permeability of blood capillaries (capillary hyperpermeability), to drain the blood through the lymphatic system. The lymphatic system slowly removes excess fluid and proteins from the veins in the lower legs towards the upper body; however, as it is not as efficient as an unimpaired circulatory system, swelling (edema) is visible, particularly in the ankles and lower leg. The chronic increased fluid in the lymphatic system and capillary hyperpermeability causes an inflammatory response which leads to tissue fibrosis of both veins and lymphatic system, opening of arteriovenous shunts, all of which then worsens the condition in a vicious cycle.

Others

Swollenlegs,feet andanklesare common in latepregnancy.The problem is partly caused by the weight of theuteruson the majorveinsof thepelvis.It usually clears up after delivery of the baby, and is mostly not a cause for concern,though it should always be reported to a doctor.

Lack of exercise is another common cause of water retention in the legs. Exercise helps the legveinswork againstgravityto returnbloodto theheart.Ifbloodtravels too slowly and starts to pool in thelegveins,the pressure can force too much fluid out of thelegcapillariesinto the tissue spaces. Thecapillariesmay break, leaving small blood marks under theskin.Theveinsthemselves can become swollen, painful and distorted – a condition known asvaricose veins.Muscleaction is needed not only to keepbloodflowing through theveinsbut also to stimulate thelymphatic systemto fulfil its "overflow" function. Long-haulflights,lengthybed-rest,immobility caused bydisabilityand so on, are all potential causes of water retention. Even very small exercises such as rotatinganklesand wigglingtoescan help to reduce it.

Certainmedicationsare prone to causing water retention. These includeestrogens,thereby including drugs forhormone replacement therapyor thecombined oral contraceptive pill,as well asnon-steroidal anti-inflammatory drugsandbeta-blockers.

Premenstrual water retention,causingbloatingandbreast tenderness,is common.

Mechanism

Six factors can contribute to the formation of edema:

1. increasedhydrostatic pressure;
2. reduced colloidal oroncotic pressurewithin blood vessels;
3. increased tissue colloidal or oncotic pressure;
4. increased blood vessel wall permeability (such asinflammation);
5. obstruction of fluid clearance in thelymphatic 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.

Generation of interstitial fluid is regulated by the forces of theStarling equation.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 oroncotic pressureof 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 capillaryvenules,which have asemi-permeable membranewall 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.

Another set of vessels known as thelymphatic systemacts like an "overflow" and can return much excess fluid to thebloodstream.But even thelymphatic systemcan be overwhelmed, and if there is simply too much fluid, or if thelymphatic systemis congested, then the fluid will remain in the tissues, causing swellings inlegs,ankles,feet,abdomenor any other part of the body.

Diagnosis

Grading of edema

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

Edema may be described aspitting edema,ornon-pitting edema.Pitting edema is when, after pressure is applied to a small area, the indentation persists after the release of the pressure.Peripheralpitting 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 ofheart failure,or local conditions such asvaricose veins,thrombophlebitis,insect bites, anddermatitis.

Non-pitting edema is observed when the indentation does not persist. It is associated with such conditions aslymphedema,lipedema,andmyxedema.

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

Treatment

Vein obstruction causes facial edema while lying down to sleep.

After being upright all day, the swelling disappears.

When possible, treatment involves resolving the underlying cause. Many cases ofheartorkidneydisease are treated withdiuretics.

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 compressioncan be used to pressurize tissue in a limb, forcing fluids—both blood andlymph—to flow out of the compressed area.