The efficacy of Gram-stain microscopy for diagnosis of septic arthritis is fundamentally limited by an inherent false-negative rate of 25–50%. The aim of this study was to calculate the sensitivity of Gram-stain microscopy of synovial fluid collected in heparinised containers and to investigate if this collection method improves diagnostic value. 12-year retrospective study of patients undergoing synovial fluid analysis between 1998 and 2010. Gram-stain result was correlated with culture result and clinical diagnosis. The formula sensitivity = number of true positives/(number of true positives + number of false negatives) was used for analysis.Objectives
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