Peripheral edema is the presence of palpable swelling resulting from increased interstitial fluid in the tissue of the extremities.  The most severe, generalized form of edema is called anasarca. Edema is caused by imbalance of the equilibrium between the hydrostatic forces that push fluid into the interstitial tissue spaces and the oncotic gradient that draws fluid into the intravascular space.  Normally, the small amount of net movement of fluid into the interstitial space is removed by lymphatic drainage. If this drainage is obstructed, edema gradually develops. 
The body has a number of homeostatic mechanisms that serve to maintain this balance, and these must be overwhelmed before fluid buildup becomes evident as peripheral edema. Clues generated by the history, physical examination, and targeted evaluation help to identify the underlying etiology of peripheral edema.
Associate Professor, College of Nursing
University of Colorado Anschutz Medical Campus
LDR declares that she has no competing interests.
Professor of Medicine
Division of Hospital Medicine
Department of Internal Medicine
University of Colorado
EC declares that he has no competing interests.
Department of Cardiology
University of Texas MD Anderson Cancer Center
SWY declares that he has no competing interests.
Basic Physician Trainee RACP
PR declares that he has no competing interests.
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