Diagnosis of Synovitis
The first thing your doctor will do is examine the affected joint. Documentation of the presence of pain, warmth, any discoloration, the range of motion, and the size will be done. Detailed information about how the joint becomes swollen will be asked to get a better idea about its onset.

Preliminary tests using ultrasound or MRI can help give an image of how much fluid accumulation has occurred within the joint. Ultrasounds, in particular, can be a speedy and convenient choice for a quick diagnosis. An x-ray may also be obtained to rule out a potential fracture. Blood tests may also be taken to help diagnose any causes of bacterial infection affecting the body. However, simply knowing that there is fluid surrounding the joint is not enough information to guide treatment. This would require the use for more specific testing.

Synovial fluid analysis involves using a syringe to collect synovial fluid directly from the affected joint – also known as joint aspiration. Once this fluid is collected it can be analyzed looking at color, clarity, viscosity, white blood cells, and polymorphonuclear leukocytes (PMN) – a category of white blood cells.