Removal of joint fluid has a dual purpose—diagnostic and therapeutic. While finding the cause of joint swelling is the goal, removing fluid may also help relieve pain and pressure on the joint.
This photo contains content that some people may find graphic or disturbing.See PhotoHenadzi Pechan / Getty Images
This photo contains content that some people may find graphic or disturbing.See Photo
This photo contains content that some people may find graphic or disturbing.
Henadzi Pechan / Getty Images
The Technique
An aseptic technique must be followed when obtaining synovial fluid for analysis. Precautions are taken so that bacteria are not introduced into the joint. A sterile needle is used to draw joint fluid from the affected joint, but first, the skin is sterilized using a topical agent, e.g., Betadine (povidone-iodine).A local anesthetic is also used.
After the fluid is withdrawn from the joint, the healthcare provider may inject medicine (usually acorticosteroid) into the joint using the same injection site.A bandage is applied after the needle has been removed.
Appearance
Microscopic Examination
Joint fluid is examined under a microscope and blood cell counts are done.
Normal joint fluid has none or few blood cells. Large numbers of red blood cells indicate bleeding in the joint. Large numbers of white blood cells can occur with infection,inflammatory arthritis,gout, orpseudogout.
Typically, a high white blood cell count suggests inflammation and a very high white blood cell count suggests an infection.
A synovial fluid culture is an important test that takes a sample of the joint fluid and examines it for infection-causing germs, such as bacteria. A culture can identify the source of a bacterial infection.
Crystals seen under a microscope are an abnormal finding.Uric acid crystalsare indicative of gout whileCPPD crystalsoccur with pseudogout.
Chemical Analysis
Although rarely used, joint fluid can also be tested for glucose, protein, and lactic dehydrogenase (LDH).Abnormal joint fluid results may indicate inflammation or infection.
Other Findings From Synovial Fluid Analysis
Joint fluid is observed in a plain tube after one hour for the formation of a fibrin clot. The quality of the clot is graded, but any clot suggests that there is a problem with the synovial membrane.
Blood testsor other laboratory tests can also be ordered with the intent of supporting the evidence derived from the synovial fluid analysis.
5 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Library of Medicine: MedlinePlus.Synovial fluid analysis.Johns Hopkins Medicine.Joint aspiration.American College of Rheumatology.Joint injections.American Academy of Family Physicians.Gout: an update.Orange DE, Blachere NE, DiCarlo EF, et al.Rheumatoid arthritis morning stiffness is associated with synovial fibrin and neutrophils.Arthritis Rheumatol. 2020;72(4):557-564. doi:10.1002/art.41141
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Library of Medicine: MedlinePlus.Synovial fluid analysis.Johns Hopkins Medicine.Joint aspiration.American College of Rheumatology.Joint injections.American Academy of Family Physicians.Gout: an update.Orange DE, Blachere NE, DiCarlo EF, et al.Rheumatoid arthritis morning stiffness is associated with synovial fibrin and neutrophils.Arthritis Rheumatol. 2020;72(4):557-564. doi:10.1002/art.41141
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Library of Medicine: MedlinePlus.Synovial fluid analysis.Johns Hopkins Medicine.Joint aspiration.American College of Rheumatology.Joint injections.American Academy of Family Physicians.Gout: an update.Orange DE, Blachere NE, DiCarlo EF, et al.Rheumatoid arthritis morning stiffness is associated with synovial fibrin and neutrophils.Arthritis Rheumatol. 2020;72(4):557-564. doi:10.1002/art.41141
National Library of Medicine: MedlinePlus.Synovial fluid analysis.
Johns Hopkins Medicine.Joint aspiration.
American College of Rheumatology.Joint injections.
American Academy of Family Physicians.Gout: an update.
Orange DE, Blachere NE, DiCarlo EF, et al.Rheumatoid arthritis morning stiffness is associated with synovial fibrin and neutrophils.Arthritis Rheumatol. 2020;72(4):557-564. doi:10.1002/art.41141
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