IntroductionFalsely elevated synovial white blood cell (WBC) counts using automated hematology analyzers have been reported particularly in the setting of joint arthroplasty. We evaluated the implementation of a laboratory workflow based on Sysmex XN‐1000‐automated cell counting and scattergram interpretation.MethodsWBC and differential were measured for 76 synovial fluid samples (29 native joints and 47 with joint arthroplasties) with Sysmex XN‐1000 and manual methods. All scattergrams were evaluated for possible incorrect WBC and/or differential according to our implemented workflow. A specific finding was the “banana‐shape” scattergram, which indicates possible interferences. The European Bone & Joint Infection Society (EBJIS) criteria were applied to identify possible prosthetic joint infections (PJIs) in patients with joint arthroplasties.ResultsCorrelation between automated and manual WBC counts, calculated for samples with WBC count <50 000/μL, was higher for native joints (r = 0.938) compared with patients known with arthroplasty (r = 0.906). Scattergrams classified as OK showed overall a higher correlation compared with scattergrams, which were interpreted as NOT OK. “Banana‐shape” scattergrams (n = 19) showed falsely elevated automated WBC count, and the patterns were mainly seen in prosthesis patients (17/19 [89%]). Six of 47 (13%) patients with joint arthroplasties were reclassified from “confirmed” to “unlikely” PJI according to the EBJIS criteria.ConclusionOur workflow based on scattergram interpretation resulted in accurate WBC counts in synovial fluid using automated/and or manual methods. It is important to identify the presence of “banana‐shape” scattergrams to avoid overestimated automated WBC counts. Overall, automated synovial WBC count can be used, even for patients with arthroplasty, but after visual inspection of the scattergram to exclude possible interferences.

中文翻译：

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在 Sysmex XN-1000 上优化滑液中白细胞计数和差异的实验室工作流程

简介 特别是在关节置换术中，已有报道称自动血液分析仪导致滑膜白细胞 (WBC) 计数错误升高。我们评估了基于 Sysmex XN-1000 自动细胞计数和散点图解释的实验室工作流程的实施情况。方法使用 Sysmex XN-1000 和手动方法测量了 76 个滑液样本（29 个天然关节和 47 个关节置换术）的白细胞和分类。根据我们实施的工作流程，对所有散点图进行了可能不正确的 WBC 和/或差异评估。一个具体的发现是“香蕉形状”散点图，它表明可能存在干扰。采用欧洲骨与关节感染协会 (EBJIS) 标准来识别关节置换术患者中可能存在的假体关节感染 (PJI)。结果针对 WBC 计数 <50 000/μL 的样本计算，自动和手动 WBC 计数之间的相关性较高对于原生关节（r= 0.938）与已知接受关节置换术的患者相比（r= 0.906）。与被解释为“不正常”的散点图相比，分类为“正常”的散点图总体上显示出更高的相关性。 “香蕉形”散点图（n= 19）显示自动白细胞计数错误升高，这种模式主要见于假体患者（17/19 [89%]）。根据 EBJIS 标准，47 名接受关节置换术的患者中有 6 名 (13%) 从“确诊”PJI 重新分类为“不可能”PJI。结论我们基于散点图解释的工作流程使用自动/和/或手动方法实现了滑液中准确的 WBC 计数。识别“香蕉形”散点图的存在非常重要，以避免高估自动白细胞计数。总体而言，即使对于进行关节置换术的患者，也可以使用自动滑膜白细胞计数，但需要在目视检查散点图以排除可能的干扰后进行。