Joint Aspiration

Alternate Names
synovial fluid analysis
synovial biopsy

Definition of Joint Aspiration

Synovial fluid is a liquid found in small amounts within the joints. This liquid is produced by the membrane lining the capsule of a joint, known as the synovial membrane. During a joint aspiration, the synovial fluid is drawn out using a needle, and examined under a microscope.

Who is a candidate for the test?

A joint aspiration is done to help diagnose joint problems in a person with joint pain, swelling, or deformity.

How is the test performed?

A joint aspiration can be done in a doctor's office. Local anesthesia may be injected into the joint to numb the area. The area is then cleaned with an antiseptic. A sterile needle is inserted into the joint space.

A small amount of the synovial fluid is withdrawn and sent to the laboratory for analysis. The procedure usually takes only a few minutes. Some discomfort may occurs as the local anesthesia is injected.

What is involved in preparation for the test?

There is no specific preparation necessary for this test.

What do the test results mean?

Normal synovial fluid is clear and light yellow in color.

Abnormal results may indicate:

• infection
• injury to the joint
• arthritis or inflammation of a joint
• a tumor or growth involving the joint
• gout, which is a form of arthritis caused by deposit of uric acid crytals into the joint
• systemic lupus erythematosus (SLE), a disease in which normal tissue is destroyed by the body's own immune defenses