Question: What is joint aspiration and how is it used to diagnose rheumatoid arthritis or osteoarthritis?
Answer: Joint aspiration is done when someone literally has a swollen joint with fluid in the joint. We all have maybe one cc of synovial fluid in, let's say, a large joint like the knee joint. You really shouldn't be able to palpate fluid in, really, any joint. When someone comes in with a swollen joint, if there's any suspicion that there's a kind of inflammation going on in the joint -- whether from rheumatoid arthritis, infection, gout -- it is very helpful to aspirate the joint -- that is, take fluid out of the joint and examine it under the microscope and see what kind of cells are in the fluid itself to see if they're abnormal or normal.