Synovial fluid lactate and the diagnosis of septic arthritis

To assess the value of synovial fluid lactate estimation in the diagnosis of septic arthritis, 238 specimens received for routine culture and 75 reference samples were examined using a rapid enzyme technique. Samples were collected without special treatment and the effect of delay in transport to the laboratory investigated. Raised levels were found in all cases of untreated septic arthritis, in six out of ten partially treated patients and in 19 out of 219 non-septic fluids. Special treatment of the sample was unnecessary if it was examined within six hours of aspiration. The predictive value of a negative result was 98 per cent and the value of the test appeared to be in the rapid exclusion of sepsis in untreated patients.