Leukocyte esterase from synovial fluid aspirate: a technical note.

Accurate and efficient diagnosis of periprosthetic joint infection remains one of the most challenging tasks for orthopedic surgeons. Currently, no widely used diagnostic test allows for quick and efficient performance, low cost, and high sensitivity and specificity. Aspiration of synovial fluid from a patient's joint can be done in the clinic both quickly and easily; oftentimes, the aspirate obtained is bloody, thus rendering the use of colorimetric strip testing impractical. We describe a simple, inexpensive, and effective protocol using centrifugation to allow for leukocyte esterase (LE) testing after bloody joint aspirations. In all cases, both septic and aseptic, there was a 100% concordance in LE enzyme test results. Although further validation may be necessary, these initial results demonstrate that accuracy of LE testing is not affected by centrifugation.