Abnormal accumulation of watery fluid in the spaces between connective-tissue cells. Usually a symptom of diseases of the kidneys, heart, veins, or lymphatic system, which affect water balance in the cells, tissues, and blood, edema can be pitting (retaining an imprint when compressed) or nonpitting. Edema may be local (e.g., hives from allergies) or generalized (also called dropsy), sometimes involving body cavities as well as tissues. Treatment must usually focus on the underlying cause.
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