• Test Overview
• Why It Is Done
• How It Is Done
• How It Feels
• Test Results
• What To Think About

Test Overview

Joint fluid analysis is a procedure that can help determine the cause of joint pain or inflammation. It can also help relieve pain and swelling caused by joint inflammation.

Normally only a small amount of joint fluid (also called synovial fluid) is found in a joint. Joint fluid acts as a lubricant for the joint and cushions joint structures. See an illustration of the joint.

If the joint is infected, injured, or inflamed, the amount of fluid may increase and the joint may become swollen, stiff, and painful. Removing a sample of joint fluid and analyzing it can help determine the cause of joint pain and swelling.

For joint fluid analysis, a sample of joint fluid is removed from the joint with a long, thin needle. This procedure is done most often on the knee, but it can also be done on other major joints in the body, including the shoulder, hip, elbow, wrist, or ankle. The joint fluid is then analyzed in a lab to look for signs of infection, bleeding, or other causes of inflammation.