Pleural effusion is a medical condition characterized by the accumulation of excess fluid in the pleural cavity, which is the space between the two layers of the pleura, a thin membrane that surrounds the lungs. The pleura helps to facilitate the movement of the lungs within the chest cavity during breathing.Pleural effusion can cause symptoms such as chest pain, shortness of breath, and coughing, and it can be associated with various underlying medical conditions. Treatment depends on the cause of the effusion and may include addressing the underlying condition, draining the excess fluid, and managing symptoms.