Exudátum

Exudátum (exudate) is a fluid produced by inflamed or damaged tissues that leaks from capillaries into surrounding tissue or cavities. It contrasts with transudate, which forms from altered hydrostatic or oncotic pressures and is relatively protein-poor.

Formation: Inflammation increases vascular permeability through mediators such as histamine, bradykinin, and cytokines. Plasma proteins, fibrinogen, immune cells, and fluid escape into interstitial spaces or body cavities, producing exudate.

Composition and appearance: Exudates are rich in proteins and cells; serous exudate is clear and watery; fibrinous contains high fibrin; purulent exudate contains neutrophils and bacteria; hemorrhagic exudate contains red blood cells and may appear bloody.

Types and contexts: Serous, fibrinous, purulent, and hemorrhagic exudates occur in infections, injuries, and in pleural, peritoneal, or pericardial spaces, as well as in wounds.

Clinical relevance: The presence of exudate suggests active inflammation or infection. Distinguishing exudate from transudate aids diagnosis; in pleural effusions, classification uses higher protein and LDH content relative to serum (Light's criteria).

Analysis and management: Exudates are analyzed for protein concentration, cell count, differential, Gram stain, culture, and cytology. Management targets the underlying cause and may involve drainage, antibiotics, or anti-inflammatory therapy.