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Draining fluid from the knee What an ultrasound-guided knee aspiration looks like
Draining fluid from the knee, called knee aspiration or arthrocentesis, is a short in-office procedure. After the skin is cleaned and numbed, a clinician uses ultrasound to see the pocket of fluid and guides a thin needle into the joint to draw the fluid out with a syringe. Removing the fluid can ease pressure, pain and stiffness, and the fluid can be sent to a lab to help find the cause of the swelling.
A swollen knee that feels tight, hard to bend and heavy is often full of extra joint fluid. In the first video above, Julia Kogan, FNP drains that fluid from a patient’s knee at our Brooklyn office. This post explains what you are seeing in these clips, what the visit is like and what comes next. For the full medical background, read our knee aspiration guide and our article on the swollen knee (water on the knee).
What happens when fluid is drained from the knee
- Exam first: the clinician asks how and when the swelling started and examines the knee.
- Ultrasound look: the probe shows where the fluid sits inside the joint.
- Cleaning and numbing: the skin is cleaned and numbed.
- Drawing the fluid: a needle is guided into the fluid pocket and the fluid is drawn into a syringe. Healthy joint fluid is clear to pale yellow; cloudy or bloody fluid can point to other causes.
- Bandage: a small bandage goes on, and the visit usually takes a few minutes.
Why ultrasound guidance helps
With ultrasound the clinician can see the fluid and the needle tip on screen during the procedure, as the second and third videos show. That helps place the needle in the fluid pocket. Guidance does not make the procedure risk-free, and your clinician will explain the small risks, such as bruising, soreness and, rarely, infection.
Draining the knee and an injection at the same visit
When the cause allows it, a corticosteroid or another medicine is sometimes injected through the same needle site after the fluid is removed, as in the last video. Read more about joint injections, or about gel injections for knee arthritis.
Fluid on the knee treatment: treating the cause
Draining the fluid eases pressure, but swelling can come back if the cause is not treated. Fluid on the knee can come from osteoarthritis, a meniscus or ligament injury, overuse, gout or, less often, infection. A plan may include rest, ice, compression and elevation at first, treatment for the cause, and strengthening once the knee calms down. Our physical therapy team in Brooklyn and Staten Island explains that stage in physical therapy for knee pain. If the swelling comes with long-lasting arthritis pain, see chronic knee pain treatment and alternatives to knee replacement. Our knee pain treatment page lists every knee problem we treat.
After a knee aspiration
- Mild soreness for a day or two is common
- Many people go back to light activity soon after; follow your clinician’s advice on how long to avoid strenuous activity
- Ice can help with soreness
- If fluid was sent to the lab, your clinician will go over the results with you
Call the office or seek care quickly if the knee becomes hot, red or more painful, if you develop a fever, or if the swelling returns fast.
When to see a doctor for a swollen knee
Get seen the same day if a swollen knee is hot and red or you have a fever, if it swelled within minutes of an injury, or if you cannot put weight on the leg. Swelling that keeps coming back also deserves an exam to find the cause.
More videos of knee fluid being drained
More clips from our YouTube channel @precisioncaremedical showing ultrasound-guided knee procedures.
Related care at Precision Care
Knee aspiration in Brooklyn
Knee aspiration is done at our Brooklyn office at 2781 Shell Rd, convenient to Gravesend, Sheepshead Bay and Bensonhurst, where Julia Kogan, FNP performs ultrasound-guided knee aspiration. If you are looking for a knee doctor in Brooklyn for a swollen knee, Ashley Marcus, MD also sees knee pain patients at this office. Request an appointment or call the Brooklyn office to ask whether draining the fluid is right for your knee.
Questions patients ask
What is knee aspiration?
Knee aspiration, also called arthrocentesis, is a short in-office procedure in which a needle and syringe are used to drain extra fluid from the knee joint after the skin is numbed. The fluid can also be tested in a lab.
Does draining fluid from the knee hurt?
The skin is numbed first, so most people feel pressure more than pain. Mild soreness for a day or two afterward is common.
Why is ultrasound used for knee aspiration?
Ultrasound lets the clinician see the fluid and the needle on screen, which helps guide the needle into the fluid pocket.
Will the fluid come back after the knee is drained?
It can, especially if the cause, such as arthritis or an injury, is still active. Treating the cause and strengthening the knee lower the chance of repeat swelling.
What can I do at home for fluid on the knee?
Rest from activities that flare it, ice, compression and keeping the leg raised can help at first. See a clinician if the knee is hot or red, you have a fever, or the swelling does not settle.
Where can I get knee fluid drained in Brooklyn?
At Precision Care, 2781 Shell Rd, Suite 101, Brooklyn, NY 11223, (718) 648-1234, convenient to Gravesend and Sheepshead Bay. Julia Kogan, FNP performs ultrasound-guided knee aspiration at this office.
Educational only, not medical advice. These videos and this article explain common problems and treatments in general terms. They are not a diagnosis or a treatment plan for you. Results vary from person to person. See a qualified clinician about your own symptoms, and call 911 or go to an emergency room for an emergency.
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