Patient education: Arthrocentesis (The Basics)

What is arthrocentesis? — 

This is a procedure to remove fluid from a joint. A joint is a place where 2 or more bones meet and let the body move freely. Joints have a liquid in them called "synovial fluid." This fluid helps the joint glide smoothly as you move. Extra fluid in a joint can cause pain and swelling, and limit movement of the joint.

With arthrocentesis, the doctor removes some of the synovial fluid.

Why might I get arthrocentesis? — 

Your doctor might order this procedure to:

●Find out the cause of a joint problem

●Ease pain in the joint

●Drain infected fluid or blood from a joint

In some cases, draining the fluid also treats the problem with the joint. In other cases, the fluid can build up again over time. The doctor might also inject a steroid medicine into the joint to help with pain and swelling.

How do I prepare for arthrocentesis? — 

The doctor or nurse will tell you if you need to do anything special to prepare. Before your procedure, your doctor will do an exam. They might send you to get tests, such as:

●Lab tests

●X-rays, CT or MRI scan, or other imaging tests – These create pictures of the inside of the body.

Your doctor will also ask you about your "health history." This involves asking you questions about any health problems you have or had in the past, past surgeries, and any medicines you take. Tell them about:

●Any medicines you are taking – This includes any prescription or "over-the-counter" medicines, plus any herbal supplements. It helps to write down and bring a list of your medicines, or bring a bag with all your medicines with you.

●Any allergies you have

●Any bleeding problems you have – Certain medicines, including some herbs and supplements, can increase the risk of bleeding. Some health conditions also increase this risk.

●Any other arthrocentesis or steroid injections you got in your joints

Ask the doctor or nurse if you have questions or if there is anything you do not understand.

How is arthrocentesis done? — 

When it is time for the procedure:

●The doctor will clean your skin over the area where they will insert the needle. In some cases, they will trim your body hair over this area.

●They might use ultrasound or a special kind of X-ray during to check the placement of the needle.

●They will give a shot of medicine to numb your skin.

●They will insert the needle, and then gently pull back or "aspirate" the fluid from your joint into the syringe.

●In some cases, they will use the same needle to inject steroids into your joint.

●They will take out the needle, and cover the area with a bandage.

●In some cases, they will send the fluid from your joint to a lab for testing.

What happens after arthrocentesis? — 

Most people can go home shortly after arthrocentesis. Before you go home, make sure you know what problems to look out for and when you should call the doctor. Make sure you understand your doctor's or nurse's instructions. Ask questions about anything you do not understand.

You should also:

●Keep the area clean. You can shower or bathe as normal.

●Rest your joint. Try to not put too much pressure on it for 24 to 48 hours.

●Consider using a cold gel pack, bag of ice, or bag of frozen vegetables on your joint every 1 to 2 hours, for 15 minutes each time. Put a thin towel between the ice (or other cold object) and your skin. Use the ice (or other cold object) as needed to help with pain.

●You can also take medicines to relieve pain, such as acetaminophen (sample brand name: Tylenol), ibuprofen (sample brand names: Advil, Motrin), or naproxen (sample brand name: Aleve).

What are the risks of arthrocentesis? — 

Your doctor will talk to you about all the possible risks, and answer your questions. Possible risks include:

●Infection

●Bleeding or bruising

●Needing to remove more fluid from the joint

●Leakage of joint fluid

●"Postinjection flare" – This is temporary pain and swelling in the joint if steroids were injected.

When should I call the doctor? — 

Call for advice if you have:

●A fever of 100.4°F (38°C) or higher, or chills

●Redness or swelling at your joint

●Pain in your joint that does not go away with pain medicines

More on this topic

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Patient education: Septic arthritis (The Basics)

Patient education: Rheumatoid arthritis treatment (Beyond the Basics)
Patient education: Joint infection (Beyond the Basics)