( of any
Organ or
Tissue due to accumulation of excess fluid, without an increase of the number of cells in the affected tissue.
Edema is the increase of
Extracellular Fluid in any organ. Generally, the amount of ECF is in balance. Increased secretion of fluid into the interstitium or impaired removal of this fluid may be associated with edema. Mechanisms causing increased secretion are
Inflammation , increased
Hydrostatic Pressure and abnormalities in
Osmolality ; abnormal removal can be found in low
Oncotic Pressure and abnormal pressure on the
Lymphatic System .
''Edema'' without a modifier usually refers to ''peripheral'' or ''dependent edema'', the accumulation of fluid in the parts of the body that are most affected by
Gravity . In ambulatory people these are the
Leg s, although in those who are bedbound the first manifestation may be
Sacral edema. If severe enough, peripheral edema may progress to involve the abdominal or even thoracic wall (this may be referred to as ''generalized'' edema or
Anasarca ). In particular edema states (e.g.
Nephrotic Syndrome , see below), ''periorbital edema'' (around the eyes) may be present.
Some phenomena may distinguish different causes of peripheral edema. Most peripheral edema is ''pitting edema'' - pressing down will lead to a shift in the interstitial fluid and the formation of a small pit that resolves over seconds. Non-pitting edema may reflect ''
Lymphedema '', a form of edema that develops when the
Lymph Vessel s are obstructed.
Causes of peripheral edema are:
Edema of specific organs (
Cerebral Edema ,
Pulmonary Edema ,
Macular Edema ) may impair function. It has different causes from peripheral edema, although pulmonary edema is seen together with peripheral edema in severe fluid overload.
Common and usually harmless appearances of cuteneous edema are observed with mosquito bites and skin contact with certain plants (
Urticaria ).
Edema in plants is the extended swelling in plant organs caused primarily by an excessive accumulation of water.
- Cho S, Atwood JE. Peripheral edema. ''Am J Med'' 2002;113:580-586. PMID 12459405.
