Understanding Your Laboratory Test: What It Is, How It Is Performed, and Why You May Need It
This test analyzes joint fluid to detect and identify anaerobic bacteria that may be causing infection.
{"The test looks for anaerobic (oxygen-avoiding) bacteria in joint fluid","It helps diagnose joint infections that may not be detected by standard tests","Sample is collected by drawing fluid from the affected joint","Results help doctors choose the right antibiotic treatment","Joint infection is a serious condition requiring prompt treatment"}
Key facts at a glance
- LOINC
- 87944-5
- Short code
- SYNANROC
- Synonyms
- Bacteria Snv Anaerobe Cult
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile, leak-proof, anaerobic transport container or syringe with sealed cap (preferred). Anaerobic transport system (e.g., BD Port-A-Cul, Copan Eswab with Amies medium, or equivalent) to maintain viability of obligate anaerobes during transport.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- anaerobic-culture
- CPT
- 87075
- SNOMED
- 104236003
- Specimen volume
- 1-5 mL of synovial fluid; minimum 1 mL acceptable. Larger volumes preferred for adequate recovery of fastidious organisms and to allow for additional studies including Gram stain, cell count, and crystal analysis.
- Stability
- Specimen should be processed within 1-2 hours of collection when transported at room temperature. If delayed, specimen must be placed in anaerobic transport medium and maintained at room temperature (20-25°C); stable up to 24 hours. Do not refrigerate as cold temperature is detrimental to anaerobic organism viability.
- Hemolysis max
- 300
- TAT
- 48–336 hours
- Order
- routine
This is a laboratory test that measures specific substances in your body to help your healthcare provider understand how well certain organs or systems are working. The results can support a diagnosis, guide treatment decisions, or be used to monitor an existing condition over time.
This test examines synovial fluid (the fluid that lubricates your joints) to find anaerobic bacteria. Anaerobic bacteria are microorganisms that can live and grow without oxygen. They can cause serious joint infections that are often harder to detect than infections caused by other bacteria. The test involves taking a sample of fluid from your joint and placing it in special containers that provide the perfect environment for anaerobic bacteria to grow, so they can be identified.
Your sample is collected by a trained healthcare professional, most often by drawing a small amount of blood from a vein in your arm using a thin needle. Depending on what the test measures, the sample may instead be a urine specimen, a nasal or throat swab, or another simple collection done at the office or lab.
A doctor will use a needle and syringe to draw fluid from your affected joint (a procedure called joint aspiration or arthrocentesis). The area will be cleaned and numbed to minimize discomfort. The fluid is then placed in special anaerobic culture bottles that prevent oxygen exposure. This process is similar to taking a blood sample but targets the fluid inside the joint itself.
Your doctor may order this test if you have symptoms that need a clearer explanation, if you have a medical condition that requires ongoing monitoring, or as part of a routine checkup. The results help identify problems early, confirm or rule out a diagnosis, and show how well your current treatment is working.
Your doctor may order this test if you have symptoms of a joint infection, such as severe pain, swelling, warmth, or redness in a joint, especially after surgery, injury, or if you have a condition that weakens your immune system. It is particularly important when standard bacterial cultures come back negative but infection is still suspected, as anaerobic bacteria require special conditions to grow and be detected.
Reference range
No growth of anaerobic bacteria (Negative). Normal synovial fluid is sterile; any isolated organism should be correlated clinically. Results reported as organism identified with colony morphology, Gram stain characteristics, and susceptibility profile when applicable.N/A
Strict aseptic technique is essential during arthrocentesis to prevent contamination. The skin overlying the joint must be thoroughly disinfected with chlorhexidine or povidone-iodine prior to aspiration. Discontinue antibiotics prior to specimen collection when clinically feasible, ideally 48-72 hours before sampling, to maximize recovery of organisms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
How long does it take to get results?
Is the joint aspiration procedure painful?
What happens if anaerobic bacteria are found?
Can I have a joint infection even if this test is negative?
Sources
- 1
- 2
- 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