When a doctor drains your knee what comes out?

When a doctor drains your knee, they typically remove excess fluid that has accumulated in the joint space, which can be caused by conditions like Arthritis, injury, or infection. The fluid may be synovial fluid, which lubricates the joint, or it can be a mixture of blood, pus, or other inflammatory substances. The procedure, known as arthrocentesis, can help relieve pain, reduce swelling, and allow for diagnostic analysis of the fluid if needed.