What is the treatment for synovial fluid with elevated white blood cell (WBC) count?

From the Guidelines

Treatment of synovial fluid with elevated white blood cell count (WBC) involves addressing the underlying infection or inflammation, with prompt empiric antibiotic therapy and joint drainage being essential for septic arthritis, as supported by the most recent study 1. The approach to treatment depends on the underlying cause of the elevated WBC count in the synovial fluid. For septic arthritis, which is a medical emergency, prompt empiric antibiotic therapy is crucial, usually starting with intravenous antibiotics like vancomycin (1g IV every 12 hours) plus ceftriaxone (1-2g IV daily) or cefepime (2g IV every 8-12 hours) until culture results are available, then narrowing to targeted therapy for 2-4 weeks total 1. Joint drainage through arthrocentesis or surgical irrigation is often necessary to remove purulent fluid. Some key points to consider in the treatment approach include:

• The importance of diagnosing the underlying cause of the elevated WBC count, which may involve laboratory tests such as Gram stain, total and differential cell counts, and aerobic and anaerobic cultures of the synovial fluid 1.
• The use of imaging studies, such as radiographs, may not be sensitive or specific for diagnosing infection, but can be useful in identifying other causes of joint pain or instability 1.
• The role of serologic tests, such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), in diagnosing prosthetic joint infection, with a combination of abnormal CRP and ESR providing the best combination of sensitivity and specificity 1.
• The recommendation to withhold antimicrobial therapy for at least 2 weeks prior to collection of synovial fluid for culture to increase the likelihood of recovering an organism 1. For inflammatory arthritis with elevated synovial WBCs, treatment may include:
• NSAIDs like naproxen (500mg twice daily)
• Intra-articular corticosteroid injections such as methylprednisolone acetate (40-80mg per large joint)
• Disease-modifying antirheumatic drugs for underlying conditions like rheumatoid arthritis
• Colchicine (0.6mg once or twice daily) for acute flares and long-term urate-lowering therapy for crystalline arthropathies like gout. Prompt treatment is crucial as delayed management of infectious arthritis can lead to joint destruction, while controlling inflammation in non-infectious causes prevents progressive joint damage.

From the Research

Treatment for Synovial Fluid with Elevated White Blood Cell (WBC) Count

The treatment for synovial fluid with an elevated white blood cell (WBC) count depends on the underlying cause of the elevation.

• If the elevation is due to infection, treatment typically involves antibiotics or other antimicrobial medications 2.
• If the elevation is due to inflammatory arthritis, such as rheumatoid arthritis or gout, treatment may involve anti-inflammatory medications, such as corticosteroids or disease-modifying antirheumatic drugs (DMARDs) 3, 4.
• In some cases, the elevation may be due to other conditions, such as osteoarthritis, and treatment may involve pain management and other supportive measures 5, 6.

Diagnostic Considerations

It's essential to note that an elevated WBC count in synovial fluid can have various causes, and a thorough diagnostic evaluation is necessary to determine the underlying condition.

• This may involve laboratory tests, such as cell count and differential, as well as imaging studies, such as magnetic resonance imaging (MRI) 5, 6.
• The synovial fluid WBC count can be used as a biomarker for synovitis on MRI and may also predict response to anti-inflammatory treatment 5.

Limitations of Synovial Fluid WBC Count

While the synovial fluid WBC count can be a useful diagnostic tool, it has limitations.

• The sensitivity and specificity of synovial fluid WBC in identifying effusion-synovitis on MRI were found to be limited in one study 6.
• Further research is needed to better understand the association between MRI and effusion-synovitis measured by synovial fluid and to determine which measure more strongly relates to synovial histopathology and patient outcomes 6.