In septic arthritis, the synovial fluid leukocyte count is typically above which threshold?

• A. 10,000-50,000
• B. 1,000-5,000
• C. Greater than 50,000
• D. 100,000-200,000

Answer: (C)

In suspected septic arthritis, synovial fluid analysis is the key clue. The infection drives a strong neutrophilic response, so the leukocyte count in the fluid is typically very high. A count above about 50,000 cells per cubic millimeter, usually with neutrophil predominance, is the classic threshold that suggests septic arthritis. While counts can be even higher (and other inflammatory conditions can occasionally raise counts into the 10,000–50,000 range), crossing the 50,000 mark makes septic arthritis the most likely diagnosis in the right clinical context.