To obtain the fluid for analysis, a sterile needle is inserted into the joint space through skin that has been specially cleaned. Once in the joint, fluid is aspirated through the needle into a sterile syringe.
Synovial fluid is normally a viscous (thick), straw colored substance found in small amounts in joints, bursae, and tendon sheaths. In the laboratory, the fluid is initially analyzed for color and clarity. It is then examined microscopically for cells (red and white cells), crystals (in the case of gout), and bacteria. In addition, there may be a chemical analysis, and if infection is a concern, a sample will be cultured to see if any bacteria grow out.
Abnormal joint fluid may look cloudy or abnormally thick.
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