Arthrocentesis (Joint Aspiration)

What is arthrocentesis?

Arthrocentesis, also called joint aspiration, is a simple procedure to draw fluid from your joint through a hollow needle. If your joint is inflamed and swollen, it will have extra fluid in it. Drawing the fluid out relieves some of the swelling and pain. It can also help your provider learn more about what’s causing it.

Arthro- means joint, and -centesis means to puncture with a needle (to draw fluid). A joint is any place in your body where two bones meet, like your knee, your hip, your elbow or your knuckle. “Aspiration” is just another term for a medical procedure to withdraw fluid (or sometimes gas) from your body.

What happens during the arthrocentesis procedure?

You can have arthrocentesis in your healthcare provider’s office, or as an outpatient procedure at the hospital. You don’t need to prepare ahead of time. When you arrive, your healthcare provider will:

• Sterilize your skin where the needle will go in
• Apply topical anesthesia to your skin
• Locate the joint capsule to aspirate, using imaging technology if necessary (they might have an ultrasound or fluoroscopy machine in the room, and sometimes, they’ll use it to guide the needle)
• If needed, inject local anesthesia into the site
• Attach a different needle to a syringe and insert it into the joint through the same pathway
• Withdraw as much fluid as possible, changing the syringe as needed
• If desired, use the same needle and pathway to inject medication into the joint
• If needed, send the drawn joint fluid to a pathology lab for a pathologist to analyze

How long does arthrocentesis take?

The whole procedure takes about 10 minutes. It might take a few more if your provider uses imaging, if you need to wait for anesthesia to work or if you’re having a joint injection with your joint aspiration.

What are the complications or problems that can develop after joint aspiration?

Complications of arthrocentesis are rare. They include:

• Infection introduced through the procedure
• Injury to a blood vessel, causing bleeding
• Allergic reactions to the anesthesia

What are the benefits of arthrocentesis?

Arthrocentesis has several purposes, and it often serves more than one at a time. It’s both therapeutic and diagnostic. It can help relieve your symptoms and set the stage for further treatment. It can also help your healthcare provider learn more about your condition when they send the sample to a lab for analysis.

Benefits include:

Pain relief. Inflammation in your joint can cause it to swell with excess fluid. This can be a major source of your joint pain. Drawing some of the fluid out reduces the swelling to relieve some of the pain.

Preparation. Arthrocentesis (joint aspiration) can also help prepare your joint for a therapeutic injection. Drawing excess fluid out makes room for injected medications that treat arthritis, like:

• Cortisone shots (steroid injections)
• Platelet-rich plasma injections
• Bone marrow aspirate concentrate (BMAC) injections
• Viscosupplementation (gel injections)

Diagnosis. Once your healthcare provider has drawn a sample of your joint fluid (synovial fluid), the sample might prove useful. They can send it to a lab to analyze (synovial fluid analysis) and check for:

• Signs of infection, like bacteria or a high white blood cell count
• Signs of injury, like joint bleeding
• Crystal deposits related to gout or pseudogout

What are potential risks or complications of arthrocentesis (joint aspiration) and joint injections?

Joint aspirations and injections are relatively safe. Rarely, these complications develop:

• Allergic reaction. Some people are allergic to the anesthetic or the injectable medication. In very rare instances, this can cause anaphylaxis, a life-threatening response.
• Infection. Rarely, people develop infections after getting steroid injections.
• Post-injection flare. An estimated 1 in 50 people develop post-injection flare several hours after getting an injection. It causes joint swelling and pain that subsides in a few days.

What happens after joint aspiration?

Your provider will bandage your joint and may advise you to rest it for a while. How long depends on your individual condition. If they sent your sample to a lab, they’ll let you know when they have the results.

When will I feel better, and for how long?

If you had joint aspiration to relieve pain and swelling, you should begin to feel relief over the next day or so. Depending on what caused the swelling and how severe it was, the relief might be temporary. Sometimes, swelling returns a few days later, and you may need another aspiration to relieve it.

If you have a chronic condition, like arthritis, your symptoms might return more gradually. Your healthcare provider can advise you on when you can have another joint aspiration and/or injection. Different types of joint injections have different rules about how often you should have them. 

When should I call my healthcare provider?

Contact your healthcare provider if you experience any unusual symptoms after your procedure, like:

• Worsening pain that doesn’t improve with pain relievers
• Redness, heat or a rash at the injection site
• Bleeding or discharge from the injection site
• Fever or chills