The process by which fluid escapes. The term also describes an abnormal collection of fluid, such as blood, pus, or plasma, in the tissues or a body cavity. An effusion can form as a result of inflammation or changes in pressure within blood vessels, or it can be due to changes in blood constituents, as in nephrotic syndrome. Effusion commonly occurs around the lung (pleural effusion) or heart (pericardial effusion) or within joints, causing swelling.
The passage of ?uid through the walls of a blood vessel into a tissue or body cavity. It commonly occurs as a result of in?ammation or damage to the blood vessel. A pleural e?usion may occur in heart failure (as a result of increased blood pressure in the veins forcing out ?uid) or as a result of in?ammation in the lung tissue (PNEUMONIA). E?usions may also develop in damaged joints.
n. 1. the escape of pus, serum, blood, lymph, or other fluid into a body cavity as a result of inflammation or the presence of excess blood or tissue fluid in an organ or tissue. 2. fluid that has escaped into a body cavity. Such effusions may be exudates (rich in protein) or transudates (low in protein).
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