What does the term effusion indicate?

Effusion refers specifically to the escape of bodily fluids from blood vessels into a body cavity or tissue, typically resulting in swelling or an accumulation of fluid. This term is often used in a medical context to describe conditions such as joint effusion, where excess synovial fluid accumulates in a joint space, or pleural effusion, where fluid collects in the pleural cavity around the lungs. By understanding effusion in this way, healthcare providers can diagnose and manage various medical conditions effectively. The other choices pertain to symptoms or conditions that do not define effusion, making them less relevant in this context.