Thoracentesis is a medical procedure used to remove excess fluid from the space between the lungs and the chest wall, known as the pleural space. This fluid buildup can cause difficulty in breathing and discomfort. During the procedure, a doctor uses a needle to carefully extract the fluid, which can then be tested to determine the cause of the accumulation. The procedure is typically performed in a hospital or clinic setting and may involve the use of ultrasound to guide the needle placement. Patients may feel some pressure or discomfort, but it is generally quick and can provide significant relief from symptoms.