Slide Preparation: Should have a wet preparation (where the fluid is mounted as received) and a fixed H&E preparation.
Using Polarisers: Variable depending on make of microscope. 2 polarisers are required. Insert first polariser. Then place second polariser and rotate 90 degrees until the field darkens. Increase intensity of light to maximum and see if any crystals can be identified. Ensure that the slide is viewed in the correct plane as sometimes crystals may be identified in the mountant. Then place the lambda plate parallel to the direction of the crystals and rotate 90 degrees. Gout crystals will be yellow when parallel to the lamda plate and blue when perpendicular.
Gout- Numerous needle like crystals which are seen yellow parallel to the lambda plate and blue perpendicular to the lamda plate (compensator). Evidence of gouty tophi. Check biochemistry for urate levels.
Pseudogout -(calcium pyrophosphate crystals) Short, broad rhomboid crystals which are blue parallel and yellow perpendicular to the lambda plate.
Rheumatoid arthritis – Ragocytes are characteristic of rheumatoid arthritis and are neutrophils with distinct lysome granules.