Joint aspiration may be both a diagnostic test and a treatment option. In conditions such as bursitis, there is a fluid build-up that results in swelling and pressure. A similar fluid build-up around the joints can occur with injuries and arthritis.
Aspiration, or removing the fluid through a syringe, can reduce swelling and relieve pressure. The doctor will swab the skin with an antibacterial solution before inserting the aspirating needle. You may feel some pressure and pain as the needle is inserted, but this should be relieved as the fluid is removed.
After the test, your doctor may send the fluid to a laboratory for analysis. In an injury situation, there may be blood present in the fluid or fat droplets from bone marrow, which indicates the presence of a fracture. The analysis can also determine if the fluids result from an infection or an inflammatory response.