The synovial fluid.

The synovial fluid is readily available for study in all cases of effusion. Whenever a question of diagnosis arises, the fluid should be removed for study. Removal of large effusions gives temporary relief of pain. The fluid removed should be smeared on a slide, stained with hematoxylin and eosin, and plated for bacterial, viral, and fungal cultures. The solid constituents of the fluid can easily be studied in the simplest of laboratories. Most of the constituents of plasma are present in synovial fluids. Quantitation of glucose, protein, and cells and an attempt to identify crystals, cartilage fragments, or even foreign bodies are crucial to therapy and the evolution of the disease.