Joint Fluid Analysis: About This Test

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What is it?

For a joint fluid analysis, the doctor uses a needle to draw a small amount of fluid out of your joint so it can be looked at under a microscope. The test can be done in your doctor's office, a clinic, an operating room, or the emergency room.

Why is this test done?

This test is done to find inflammation, infection, gout, or pseudogout. Removing some of the joint fluid may also relieve pain caused by the buildup of fluid in your joint.

How can you prepare for the test?

  • In general, you don't need to prepare before having this test. Your doctor may give you some specific instructions.

What happens during the test?

  • You will sit or lie down on an examining table.
  • After the joint area is cleaned, a local anesthetic may be injected into your skin to numb the area.
  • 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.
  • A cortisone shot may be given into the joint before this 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.

What else should you know about the test?

  • The joint may be sore for 1 to 2 days after the test.

How long does the test take?

  • The test will take about 20 minutes.

What happens after the test?

  • You will probably be able to go home right away.
  • You can go back to your usual activities right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

When should you call for help?

Call your doctor or nurse call line now or seek immediate medical care if:

  • You have signs of infection, such as:
    • Increased pain, swelling, warmth, or redness.
    • Red streaks leading from the catheter site.
    • Pus draining from the catheter site.
    • A fever.

Where can you learn more?

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