Edema;

                           refers to an accumulation of interstitial fluid to a point where it is palpable or visible.

In general this point is reached with a fluid volume of 2–3 L. Edema formation is the result of a shift of fluid into the interstitial space due to primary disturbances in the hydraulic forces governing transcapillary fluid transport, and of subsequent excessive fluid reabsorption by the kidneys. Deranged capillary hydraulic pressures initiate edema formation in congestive heart failure and liver cirrhosis, whereas a deranged plasma oncotic pressure is leading to edema in nephrotic syndrome and malnutrition. Increased capillary permeability is responsible for edema in inflammation and burns.