Automated evaluation of synovial and ascitic fluids with the advia 2120 hematology analyzer

Objectives: The purpose of this study was to determine if the Advia 2120 hematology analyzer (Siemens Healthcare Diagnostics, Deerfield, IL) can accurately quantify both WBCs and the proportion of neutrophils from synovial and ascitic body fluids. Methods: We analyzed 60 samples on the Advia and compared the results with manual counts and smear reviews. We also assessed the effect of adding hyaluronidase to the samples. WBC counts and the proportion of neutrophils reported by the hematology analyzer were harmonized and highly correlated with manual counts and fluid smear reviews. Results: The addition of hyaluronidase to the synovial fluid consistently increased the WBC counts on both manual and automated analysis (P < .001). Conclusions: We conclude that the Advia hematology analyzer can be used for WBC and neutrophil counting of cells in synovial and ascitic fluids. Hyaluronidase should be added before manual or automated counting of cells in synovial fluids. Analyzers routinely used for a complete blood count can potentially replace manual counting and fluid smear review for various body fluids. The Advia 2120 hematology analyzer (Siemens Healthcare Diagnostics, Deerfield, IL) has received Food and Drug Administration approval for analyzing pleural and ascitic fluid on a special channel of the analyzer. This channel counts total nucleated cells (TNCs), but has not been approved for synovial fluid analysis, and does not determine the proportion of neutrophils, which is thought to be important in differentiating septic joints and bacterial peritonitis from less emergent conditions. Therefore, even for the analysis of ascitic fluid, a manual smear review is still required to determine if the absolute neutrophil count is elevated. Automated analyzers are usually not used to analyze synovial fluids because of the presence of substances that increase the viscosity of the fluid1 that can clog the flow cell and result in a malfunction.2 In the following study, we examined ascitic and synovial fluids, comparing manual counts and differentials to those determined with the Advia 2120 analyzer. Furthermore, we also assessed the effect of adding hyaluronidase to the synovial samples.