OSMT (Ontario Society of Medical Technologists) Practice Exam

How are crystals in joint fluid best viewed?

1. Light microscopy

2. Polarized light microscopy

3. Fluorescent light microscopy

4. Electron microscopy

The correct answer is: Polarized light microscopy

Viewing crystals in joint fluid is most effectively done using polarized light microscopy. This method allows for the identification and differentiation of various types of crystals based on their optical properties. Crystals such as monosodium urate (which are associated with gout) and calcium pyrophosphate (linked to pseudogout) display distinct characteristics when viewed under polarized light, enabling an accurate diagnosis. Light microscopy does provide a general view of cellular components and might reveal some aspects of the joint fluid; however, it lacks the ability to enhance the contrast and differentiation of crystalline structures as effectively as polarized light microscopy. Fluorescent light microscopy is not typically utilized for crystal analysis since it relies on the visualization of specific fluorescent markers, which are not relevant for identifying most crystalline structures. Electron microscopy, while powerful in resolving detail at a nanoscale, is not practical for routine analysis of joint fluid due to the complexity and preparation required, along with not providing the necessary information about the orientation and type of crystalline structure.