At a Glance
Why Get Tested?
When to Get Tested?
When one or more of your joints are swollen, red, and/or painful
A synovial fluid sample is obtained by inserting a needle into the space between the bones at a joint
Test Preparation Needed?
Consult with your doctor; synovial fluid collection and analysis may be performed after fasting or at random.
The Test Sample
What is being tested?
Synovial fluid is a thick (viscous) liquid that acts as a lubricant for the major joints of the body. It is found in small quantities in the spaces between the joints, where the fluid is produced and contained by synovial membranes. Synovial fluid cushions the bone ends and reduces friction during joint movement in the knees, shoulders, hips, hands, and feet.
Synovial fluid analysis consists of a group of tests that detect changes in synovial fluid that may indicate the presence of diseases that affect joint structure and function. It usually involves an initial basic set of tests, followed by additional tests that are selected based upon the results of the first set of tests, the person's symptoms, and the disease that the doctor suspects is the cause of the symptoms. Tests can be grouped according to the type of exam that is performed into:
- Physical characteristics—an evaluation of the appearance of the fluid
- Chemical tests—detect changes in the chemical constituents of the fluid
- Microscopic examination— cells and crystals that may be present are counted and identified by type under a microscope
- Infectious disease tests—detect and identify microorganisms, if present
How is the sample collected for testing?
A sample of synovial fluid is collected by a doctor from the affected joint with a syringe and needle using a procedure called an arthrocentesis.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Consult with the doctor about test preparation. Synovial fluid collection and analysis may be performed after fasting or at random.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Vorvick, L. (Updated 2011 June 4). Synovial fluid analysis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003629.htm. Accessed February 2012.
Sweiss, N. et. al. (Updated 2012 February 7). Septic Arthritis Aspiration Techniques and Indications for Surgery. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/1268807-overview through http://emedicine.medscape.com. Accessed February 2012.
Berman, J. and Paget, S. (Modified 2009 January). Evaluation of the Patient With Joint Disorders. Merck Manual for Healthcare Professionals [On-line information]. Available online through http://www.merckmanuals.com. Accessed February 2012.
(© 1995–2012). Test ID: CCBF8419 Cell Count and Differential, Body Fluid. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8419 through http://www.mayomedicallaboratories.com. Accessed February 2012.
(© 1995–2012). Test ID: SFC8719 Crystal Identification, Synovial Fluid. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/8719 through http://www.mayomedicallaboratories.com. Accessed February 2012.
(2011 July) Questions and Answers about Arthritis and Rheumatic Diseases. National Institute of Arthritis and Musculoskeletal and Skin Diseases [On-line information]. Available online at http://www.niams.nih.gov/Health_Info/Arthritis/arthritis_rheumatic_qa.asp through http://www.niams.nih.gov. Accessed February 2012.
Lehman, C. and Roberts, W. (Updated 2011 May). Hyperuricemia – Gout. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Gout.html?client_ID=LTD#tabs=0 through http://www.arupconsult.com. Accessed February 2012.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 132-135.
Sources Used in Previous Reviews
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 133-136.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. 1006-1007.
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition]. pp 1890.
Forbes, B. et. al. (© 2007). Bailey & Scott's Diagnostic Microbiology, Twelfth Edition: Mosby Elsevier Press, St. Louis, Missouri. Pp 904 – 913.
Joseph, T. (2007 May 6). Synovial fluid. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003629.htm. Accessed on 6/21/08.
Lee, S. (2007 April 27, Updated). Septic arthritis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000430.htm. Accessed on 6/21/08.
Lee, S. (2007 June 18, Updated). Gout – chronic. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000424.htm. Accessed on 6/21/08.
Zeller, J. et. al. (2007 April 4). Septic Arthritis. JAMA Patient Page JAMA. 2007;297(13):1510 [On-line information]. PDF available for download at http://jama.ama-assn.org/cgi/reprint/297/13/1510.pdf through http://jama.ama-assn.org. Accessed on 6/21/08.
Lee, S. (2007 April 26, Updated). Acute gouty arthritis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000422.htm. Accessed on 6/21/08.
Jacobs DS, DeMott WR, Oxley DK: Jacobs & DeMott Laboratory Test Handbook, 5th ed. LexiComp:Hudson, OH. Pp323-325, 2001.