In synovial fluid analysis, which WBC count is more consistent with an inflammatory process?

In synovial fluid analysis, which WBC count is more consistent with an inflammatory process?

• A. <2000/mm3
• B. 0-500/mm3
• C. >2000/mm3
• D. >100,000/mm3

Answer: (C)

In synovial fluid, the number of white blood cells reflects how active the joint’s immune response is. Normal synovial fluid has very few WBCs, so when inflammation occurs, leukocytes migrate into the joint and the count rises into the thousands per cubic millimeter. Therefore, a WBC count greater than 2000/mm3 indicates inflammatory activity in the joint. As counts rise further, infection becomes more likely (septic arthritis often shows very high counts, sometimes tens of thousands per mm3, with neutrophil predominance), but the key marker for inflammation is surpassing that 2000/mm3 threshold.

In synovial fluid, the number of white blood cells reflects how active the joint’s immune response is. Normal synovial fluid has very few WBCs, so when inflammation occurs, leukocytes migrate into the joint and the count rises into the thousands per cubic millimeter. Therefore, a WBC count greater than 2000/mm3 indicates inflammatory activity in the joint. As counts rise further, infection becomes more likely (septic arthritis often shows very high counts, sometimes tens of thousands per mm3, with neutrophil predominance), but the key marker for inflammation is surpassing that 2000/mm3 threshold.