Which description of synovial fluid is most consistent with septic arthritis?

Which description of synovial fluid is most consistent with septic arthritis?

• A. Septic arthritis
• B. Inflammatory fluid
• C. Non-inflammatory fluid
• D. Normal joint fluid

Answer: (A)

Septic arthritis reflects infection of the joint, so the synovial fluid itself is infected and typically purulent. The description that fits best is fluid from a septic joint because it signals an infectious process rather than a purely inflammatory or normal state. In septic arthritis, the fluid usually contains a high white cell count with neutrophil predominance and other inflammatory changes driven by bacteria, and cultures or Gram stain can identify the organism. This distinguishes it from inflammatory fluid seen in autoimmune or crystal-related arthritis, which can be inflammatory but not infected, non-inflammatory fluid seen in degenerative conditions, and normal joint fluid, which is clear with few cells.

Septic arthritis reflects infection of the joint, so the synovial fluid itself is infected and typically purulent. The description that fits best is fluid from a septic joint because it signals an infectious process rather than a purely inflammatory or normal state. In septic arthritis, the fluid usually contains a high white cell count with neutrophil predominance and other inflammatory changes driven by bacteria, and cultures or Gram stain can identify the organism. This distinguishes it from inflammatory fluid seen in autoimmune or crystal-related arthritis, which can be inflammatory but not infected, non-inflammatory fluid seen in degenerative conditions, and normal joint fluid, which is clear with few cells.