Synovial Fluid Differential Cell Count
A joint-fluid test that counts and classifies white blood cells to help evaluate infection, inflammation, or crystal-related arthritis.
["This test helps determine whether joint fluid contains a high proportion of certain immune cells, which can guide evaluation for infection or inflammatory arthritis."]
Key facts at a glance
- LOINC
- 12144-2
- Short code
- Sys flow/Dias DOP
- Synonyms
- Sys flow/Dias DOP
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-doppler
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
A synovial fluid differential cell count examines fluid removed from a joint. It measures the total white blood cell count and the proportions of neutrophils, lymphocytes, monocytes, eosinophils, and other cells.
Why might I need this test?
This test may be ordered when joint pain, swelling, redness, or warmth suggests infection, inflammatory arthritis, or a buildup of crystals such as uric acid. It is usually part of a broader synovial fluid analysis that may also include crystal examination, glucose testing, and culture.
How is the test performed?
A clinician removes a small amount of joint fluid with a needle during a procedure called arthrocentesis. The laboratory examines the fluid, using microscopy or counting methods to determine the number and types of white blood cells present.
How do I prepare for the test?
No special preparation is usually required. Follow your clinician's instructions for the joint aspiration, and tell the healthcare team if you have a bleeding disorder, take blood thinners, or have a joint infection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An increased white blood cell count generally indicates inflammation within the joint. A predominance of neutrophils can occur with infection, crystal arthritis, or other inflammatory conditions, so results are interpreted with symptoms, joint-fluid findings, cultures, and other laboratory tests. A low or normal count may be seen when the source of joint symptoms is not inflammatory.
Short name
Synovial fluid differential
Frequently asked questions
Is a synovial fluid differential the same as a routine blood count?
Does this test diagnose arthritis by itself?
Will I need to stop any medications before the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy