Joint fluid analysis is a test to look at joint fluid under a microscope for problems such as infection, gout, pseudogout, inflammation, or bleeding. The test can help find the cause of joint pain or swelling.

Normally, only a small amount of joint fluid is found in a joint. Joint fluid acts as a lubricant for the joint and cushions joint structures. If you have a joint problem, you may have more fluid in your joint and your joint may become swollen, stiff, and painful.

A sample of joint fluid can be taken from any joint in your body. The joint fluid is then analyzed in a lab to look for a bacterial infection, gout, pseudogout, or bleeding.

Why It Is Done

Joint fluid analysis is done to:

• Find infection, gout, or pseudogout.
• Relieve pain caused by the buildup of fluid in your joint.

After removing the joint fluid, your doctor may give you medicine, such as corticosteroids, into the joint to help keep fluid from building back up.

How To Prepare

Tell your doctor if you:

• Have taken aspirin recently.
• Are taking any medications that can delay blood clotting, including nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen, naproxen, or etodolac) or warfarin (Coumadin).
• Are allergic to any medications, including anesthetics.
• Have any bleeding problems.
• Are or might be pregnant.

Talk to your doctor about any concerns you have about the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

Joint fluid analysis takes about 20 minutes and can be done in your doctor's office, clinic, operating room, or emergency room. Depending on which joint will be examined, you may be asked to undress and put on a hospital gown. You will sit or lie down on an examining table.

Your doctor will examine the joint to determine where the needle should be inserted. The skin over the joint area will be cleaned with antiseptic solution. A local anesthetic is often injected into the skin over the joint. For young children, a sedative may also be given.

A long, thin needle is slowly inserted in the joint area. A syringe attached to the needle is used to remove a sample of joint fluid. Samples of the fluid may be put in special tubes or containers and sent to the lab. A cortisone shot may be given into the joint before the needle is removed.

A tight (pressure) bandage will be placed over the site to reduce swelling and bruising. An elastic bandage may also be wrapped around your joint, such as your knee, to reduce swelling.