Joint aspiration (draining fluid from a joint)
joint aspiration · joint tap · draining fluid from the knee · arthrocentesis · removing fluid from a joint
The doctor uses a thin needle to draw out extra fluid from a joint. This reduces swelling, and the fluid can be sent for testing.
For a swollen joint, to find the cause: inflammation, gout, infection or injury. Sometimes medicine is injected at the same time.
⏱ Duration: usually 10 to 20 minutes; the fluid test takes from one day to several
Be sure to tell your doctor
How to prepare
- Food. Usually you can eat as normal.
- Medicines. Do not stop them on your own.
- Clothing. Loose clothes, so the joint is easy to uncover.
What to bring
- Your referral
- Scans and ultrasound of the joint
- Your ID
How it goes
- You lie or sit and the joint is placed comfortably
- Your skin is cleaned with antiseptic
- A numbing injection is given
- The doctor puts the needle into the joint, often guided by ultrasound
- The fluid is drawn into a syringe, and sometimes medicine is injected
- A plaster is put over the needle spot
What you'll feel
- The numbing injection
- Pressure in the joint during the tap
- Afterwards the swelling usually goes down and the joint moves more easily
Afterwards
- Go easy on the joint for a day
- If medicine was injected, rest for a day or two
- You can apply cold through a cloth if your doctor allows it
- Discuss the fluid test results with your doctor
Contact a doctor straight away if
- Fever, or the joint becomes hot and red
- Severe pain or swelling that grows
- Pus from the needle spot
Common questions
Will the fluid come back?
Sometimes. It depends on the cause, which is why the fluid test matters.
Does it hurt?
Usually it is bearable. The skin is numbed, and what is unpleasant is mainly the pressure.