When performing arthrocentesis in suspected IMPA, which joints would be ideal to sample?

When performing arthrocentesis in suspected IMPA, which joints would be ideal to sample?

• A. Elbows and stifles
• B. Carpi and tarsi
• C. Hips and shoulders
• D. MCP joints

Answer: (B)

In immune-mediated polyarthritis, the disease usually affects multiple peripheral joints, and obtaining synovial fluid from joints that are commonly inflamed and easy to access maximizes diagnostic yield. The carpal and tarsal joints fit this pattern: they are shallow, often show effusion in IMPA, and are straightforward to aspirate under sedation. Sampling these joints provides synovial fluid for cytology and culture, helping you detect the inflammatory neutrophilic profile typical of IMPA and rule out septic arthritis. Deep joints like the hips and shoulders are harder to access and less likely to provide diagnostic fluid in this context, while the small MCP joints are less commonly involved. So, targeting the carpi and tarsi gives the best balance of likelihood of pathology and practicality.

In immune-mediated polyarthritis, the disease usually affects multiple peripheral joints, and obtaining synovial fluid from joints that are commonly inflamed and easy to access maximizes diagnostic yield. The carpal and tarsal joints fit this pattern: they are shallow, often show effusion in IMPA, and are straightforward to aspirate under sedation. Sampling these joints provides synovial fluid for cytology and culture, helping you detect the inflammatory neutrophilic profile typical of IMPA and rule out septic arthritis. Deep joints like the hips and shoulders are harder to access and less likely to provide diagnostic fluid in this context, while the small MCP joints are less commonly involved. So, targeting the carpi and tarsi gives the best balance of likelihood of pathology and practicality.