Joint aspiration (arthrocentesis) is a procedure to remove fluid from a joint using a needle and syringe. It is performed for diagnostic purposes (to analyse the fluid) or for therapeutic relief of a swollen, painful joint.
The skin over the joint is cleaned with antiseptic. Local anaesthetic is injected to numb the area. A needle is inserted into the joint space and fluid is withdrawn. The fluid may be sent for analysis (microscopy, culture, crystal analysis). A corticosteroid injection may be given into the joint at the same time. The procedure takes 10–15 minutes.
Joint aspiration is recommended for diagnosis of joint infection (septic arthritis — a surgical emergency), crystal arthropathy (gout, pseudogout), inflammatory arthritis flare, and unexplained joint effusion. It is also used therapeutically to drain large, uncomfortable joint effusions.
Blood tests and imaging can provide useful information but cannot definitively diagnose joint infection or crystal arthropathy. When infection is suspected, joint aspiration is essential and urgent.
No fasting required. Inform the team about blood-thinning medications. The procedure can usually be performed in clinic or at the bedside.
Definitive diagnosis of the cause of joint swelling. Therapeutic relief from draining a tense, painful effusion. If corticosteroid is injected, additional pain relief over the following days.
Brief pain during needle insertion. Local anaesthetic minimises this.
Minor bruising at the needle site.
The fluid may reaccumulate if the underlying cause is not treated.
Introduction of infection into the joint. Risk approximately 1 in 10,000 to 1 in 50,000 with proper sterile technique.
Significant bleeding into the joint (haemarthrosis). Very rare.
Very rare with proper needle placement.
Temporary increase in pain for 24–48 hours after corticosteroid injection.
Local anaesthetic only. No sedation or general anaesthesia required.
No significant recovery period. The joint may feel more comfortable immediately after fluid removal. Rest the joint for 24 hours after the procedure. If a corticosteroid was injected, avoid heavy loading for 48 hours.
Fluid analysis results are usually available within 24–48 hours (urgent microscopy and culture) to one week (crystal analysis). Follow-up depends on the results.
There is brief discomfort from the local anaesthetic injection and needle insertion. Most patients tolerate it well.
If joint infection is suspected, initial microscopy results are available within hours. Culture results take 24–48 hours. Crystal analysis is usually available within 24 hours.