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Abstract
Background
To enumerate leukocyte count in cerebrospinal fluid (CSF) is important for diagnosing bacterial meningitis. Using automated hematology analyzer for enumeration of leukocyte in CSF is below the sensitivity, so microscopic hemocytometric method is standard method. But this requires sufficient practical experience and has limitation of accuracy and stability. So we developed new manual method and evaluated it.
Methods
We designed new method using transparent ruler tape. We performed correlation, accuracy and precision test by counting leukocyte in diluted EDTA blood with three methods: new method, Neubauer and Nageotte hemocytometry. Twenty two CSF were used for stability test, which determines leukocyte count according to time (within one hour and after 2, 4 and 12 hr), by new method and Neubauer hemocytometry at room temperature.
Results
There was no clinical significant difference between three methods in correlation test, whereas Neubauer and Nageotte hemocytometry showed a bias to underestimation relative to the results obtained with new method in case with low leukocyte count. The new method showed the lowest CV and most accurate result. In stability test, leukocyte counts decreased being 44.4%, 72.1% of initial values after 2 hr, 14.8%, 31.1%, after 4 hr and 4.2%, 8.7%, after 12 hr, by Nageotte hemocytometry and new method, respectively.
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Fig. 1.
Slide with transparent ruler tape for cell count (A), visual fields of microscope ×40 (B), ×100 (C), ×200 (D), ×400 (E).
Fig. 2.
Schematic figure of new counting method. The arrow indicates direction in microscopic examination.
Fig. 4.
Linearity of leukocyte counting with three method; Neubauer hemacytometer (A), Nageotte chamber (B), new counting method (C) using diluents of EDTA blood samples. Each point represent an individual observation (N=10).
Fig. 5.
Leukocyte count (/μL) change with Nageotte chamber (A) and new counting method (B) of each samples (6 cases of initial WBC count >50/μL) according to time elapse.
Table 1.
Comparison of methods for white blood cell enumeration applied on Neubauer hemocytometer, Nageotte chamber counting and New method by using a different amounts of diluents of EDTA blood
Table 2.
Comparison of methods for white blood cell enumeration by Nageotte chamber and New method during storage at room temperature
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