Emergency joint aspiration: a guide for radiologists on call.

Septic arthritis is a disabling and possibly life-threatening disease that requires early diagnosis for optimal management. It is important that clinical and imaging features of septic arthritis be promptly identified. In addition, because other disease entities may have characteristics similar to those of septic arthritis, analysis of a needle biopsy specimen may be necessary for differential diagnosis. Radiologists may be asked to perform emergent aspiration of a possibly infected joint. It is important that those who perform aspiration procedures be familiar with a safe and effective imaging-guided arthrocentesis technique that is tailored to the individual patient and the specific joint affected.