Joint fluid culture is a laboratory test to detect infection-causing organisms in a sample of fluid surrounding a joint.

A sample of joint fluid is needed. This may be done in a doctor's office using a needle, or during an operating room procedure. For more information on this procedure, see joint fluid aspiration.

The fluid sample is sent to a laboratory where it is placed in a special dish and watched to see if bacteria, fungi, or viruses grow. This is called a culture.

If such microorganisms are detected, other tests may be done to further identify the infection-causing substance and determine the best treatment.

There is no special preparation needed for the lab culture. For information on preparing for the removal of joint fluid, see joint fluid aspiration.

The joint fluid culture is done in a laboratory and does not involve the patient.

For information on how the procedure to remove joint fluid feels, see joint fluid aspiration.

Your doctor may order this test if you have unexplained pain and inflammation of a joint or a suspected joint infection.

The test result is considered normal if no organisms (bacteria, fungi, viruses) grow in the laboratory dish.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Abnormal results are a sign of infection in the joint. Infections may include:

• Fungal arthritis
• Gonococcal arthritis
• Non-gonococcal (septic) bacterial arthritis

There are no risks to the patient associated with a lab culture. For risks related to the removal of joint fluid, see joint fluid aspiration.