Arthrocentesis is a diagnostic test that is performed to determine the cause of joint swelling or arthritis, including septic bursitis, gout, or rheumatoid arthritis. Also known as joint aspiration, the procedure uses a sterile needle and syringe to drain fluid from a joint for further examination.
Following removal, the fluid can be tested for white blood cell count, formation of crystals, or presence of certain proteins or glucose, and can also be culture to detect infection.
In addition to providing diagnostic information, arthrocentesis can help relieve the pain and swelling in a joint by removing inflamed fluid. In some cases, medication may be injected following fluid removal to further relieve pain and inflammation.