What is it? The synovial fluid is produced by the synovial membrane to keep the joints and cartilage lubricated and reduce friction when the joints move. The doctor removes several drops of the fluid by suctioning it through a tiny needle so that it can be looked at under a microscope. This procedure is called arthrocentesis.
What the results show. The fluid allows the doctor to distinguish between different types of arthritis.
The synovial fluid of people with osteoarthritis typically:
- is clear yellow, thick, and sticky
- may contain tiny fragments of loosened cartilage
- contains a low number of white blood cells
The synovial fluid of people with rheumatoid arthritis typically:
- is yellow to greenish
- is not thick or sticky
- does not contain loose bits of cartilage
- contains large numbers of white blood cells (High levels of white blood cells are a sign of inflammation in the joint.)