Synovial fluid is a viscous liquid that acts as a lubricant for the major joints of the body. It is found in small quantities in the spaces between the joints, where the fluid is produced and contained by synovial membranes. Synovial fluid cushions the bone ends and reduces friction during joint movement in the knees, shoulders, hips, hands, and feet. Synovial fluid analysis consists of a group of tests that detect changes in synovial fluid that may indicate the presence of diseases that affect joint structure and function. Tests performed on a sample of synovial fluid may include physical characteristics (color, and degree of turbidity), chemical tests (pH, LDH, total protein and glucose level), microscopic examination (cell count), and detect microorganisms, if present. Synovial fluid analysis may be ordered to help diagnose the cause of joint inflammation, pain, swelling, and fluid accumulation. The most important reason for performing synovial fluid analysis is to rule out septic arthritis.