What does crystals in synovial fluid mean?
In this regard, what microscopy technique is recommended for crystal identification on synovial fluid?
Polarised light microscopy of synovial fluid is an established diagnostic technique widely regarded as reliable for the detection of crystals. The threshold concentration of crystals which can be detected has been investigated and the sensitivity and specificity of six observers compared.
- Colour: Yellow.
- Clarity: Cloudy.
- Viscosity: Decreased.
- WBC: 2000–50,000 cells/mm3
- Neutrophils: >50 %
- Gram stain: Negative.
- Crystals: Positive. Gout – needle negative birefringent crystals. Pseudogout – rhomboid positively birefringent crystals.
Consequently, what is the normal WBC count in synovial fluid?
WBC count is one the most frequent tests performed on synovial fluid. Normally, synovial fluid contains less than 200 cells/µL. This count increases significantly in infections and inflammation.
The presence of uric acid crystals in the synovial fluid indicates gout. The presence of calcium pyrophosphate crystals in synovial fluid indicates pseudogout. A white blood cell count that is higher than normal may indicate infectious arthritis, gout, or rheumatoid arthritis.