effusion /ifyo̅o̅″zhən/ [L, effundere, to pour out] , 1. the escape of fluid, for example, from blood vessels as a result of rupture or seepage, usually into a body cavity. The condition is usually associated with a circulatory or renal disorder and is often an early sign of congestive heart disease. The term may be associated with an affected body area, as pleural or pericardial effusion. See also edema, transudate. 2. the outward spread of a bacterial growth.
