II. Indications

  1. Single most important test in Arthritis evaluation
  2. Septic Joint
  3. Crystal-Induced Arthritis (e.g. Gouty Arthritis, Pseudogout)

III. Contraindications

  1. Overlying infection (unable to access joint without passing through infected tissue)

IV. Preparation

  1. Ultrasound
  2. Tubes
    1. Heparinized Tube for crystal analysis
    2. Saline Tube for Cell Count
    3. Culture container
    4. Syringe (20 cc)
  3. Aspiration Needle
    1. Adequate guage (18-22 gauge) to aspirate Synovial Fluid
    2. Adequate Length (1.5" for superficial joints, 3.5" spinal needle for deeper joints)
  4. Skin Preparation
    1. Lidocaine 1% with Epinephrine
    2. Chlorhexidine (or Betadine) skin antiseptic
    3. Sterile drape

V. Procedure: Arthrocentesis

VI. Labs: Synovial Fluid Volume and Appearance

  1. Normal Synovial Fluid
    1. Slightly yellow, straw colored
    2. Clear (Can read newsprint through the fluid)
    3. Viscous consistency
    4. No clotting
  2. Inflammatory fluid
    1. Yellow green to gray
    2. Cloudy to Opaque
    3. Decreased viscosity to Watery consistency
  3. Findings suggestive of acute Fracture or derangement
    1. Large fat droplets (sensitive for Fracture)
    2. Bloody fluid

VII. Labs: Synovial Fluid Gram Stain and Culture

  1. Bacteria (Anaerobes if arthroplasty)
  2. Mycobacteria, Fungal Culture on tissues

VIII. Labs: Other Specific Synovial Fluid Tests

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