Aspiration of a joint yields clear, transparent fluid with fewer than 200 WBCs and less than 25% PMNs. What is the most likely diagnosis?

• A. Normal joint fluid
• B. Septic fluid
• C. Inflammatory joint fluid
• D. Gouty fluid

Answer: (A)

Interpreting synovial fluid relies on cell counts and neutrophil percentage. Normal joint fluid is clear and straw-colored, with very low cellularity—typically fewer than 200 white blood cells per microliter and neutrophils making up less than 25% of that count. The described fluid fits these values exactly, so this pattern most likely represents normal synovial fluid. In contrast, septic arthritis shows a markedly higher WBC count (often well above 50,000/µL) with neutrophil predominance and usually turbid or purulent appearance, while inflammatory arthritis raises the cell count but not to septic levels and often with a higher neutrophil fraction; gouty fluid may be inflammatory and occasionally crystal-rich, but the basic picture here aligns best with normal fluid.