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Arthrocentesis is a procedure in which a needle is inserted into a joint to remove synovial fluid. It is also called joint aspiration. The procedure can be diagnostic, therapeutic, or both. Fluid obtained from the joint can be examined for infection, crystals, blood, inflammation, and other abnormalities.
read more about arthrocentesis ...Arthrocentesis is performed to investigate an unexplained swollen, painful, or inflamed joint. It is particularly valuable when septic arthritis, gout, pseudogout, or bleeding into the joint is suspected. Removing a large effusion can also reduce pressure, pain, and restricted movement. Medication can sometimes be injected into the joint after aspiration when infection has been appropriately excluded and the treatment is indicated.
The skin over the joint is cleaned using sterile technique, and local anesthetic can be used. A needle is advanced into the joint space using anatomical landmarks or ultrasound guidance. Synovial fluid is withdrawn into one or more syringes and sent for appropriate laboratory tests. The needle is removed after aspiration, and a small dressing is placed over the puncture site.
Most patients can leave shortly after an uncomplicated arthrocentesis. Mild soreness or bruising at the needle site can occur for a short period. Activity instructions depend on the joint, the amount of fluid removed, and whether medication was injected. Increasing pain, fever, redness, drainage, or rapidly recurring swelling should be reported because these findings can signal infection or another complication.
Complications are uncommon when the procedure is performed using proper technique. Risks include joint infection, bleeding, bruising, pain, vasovagal symptoms, and injury to nearby cartilage, tendons, nerves, or blood vessels. Bleeding risk can be higher in patients with a clotting disorder or certain anticoagulant treatments. A dry tap can occur when little fluid is present or the needle does not enter the fluid collection.
Yes. Both terms describe inserting a needle into a joint and withdrawing synovial fluid.
Yes. Finding monosodium urate crystals in synovial fluid can support a diagnosis of gout and help distinguish it from other causes of joint inflammation.
Yes. Synovial fluid cell counts, Gram stain, culture, and other tests can help diagnose septic arthritis. Suspected joint infection requires urgent evaluation.
No. Most procedures are performed with local anesthetic and do not require general anesthesia. Sedation can be used in selected circumstances.
Arthrocentesis. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK557805/. Date Accessed August 12, 2026.
Arthrocentesis (Joint Aspiration): What It Is & Procedure. Cleveland Clinic. https://my.clevelandclinic.org/health/treatments/14512-arthrocentesis-joint-aspiration. Date Accessed August 12, 2026.
How To Do Knee Arthrocentesis. Merck Manual Professional Edition. https://www.merckmanuals.com/professional/musculoskeletal-and-connective-tissue-disorders/how-to-do-arthrocentesis/how-to-do-knee-arthrocentesis. Date Accessed August 12, 2026.
Synovial Fluid Analysis. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK537114/. Date Accessed August 12, 2026.
Approach to Septic Arthritis. American Family Physician. https://www.aafp.org/pubs/afp/issues/2011/0915/p653.html. Date Accessed August 12, 2026.