Performance of the Sysmex XN-V body fluid module for canine cerebrospinal fluid cell count

Background: Microscopic cell counts and nucleated cell identification are the “gold standard” for cerebrospinal fluid (CSF) assessments and are labor intensive and subject to operator variability. The use of automated methods could be an alternative to the current manual technique. Objectives: We aimed to assess the utility of the Sysmex XN-V body fluid (BF) module analyzer to count and differentiate nucleated cells in canine CSF and evaluate the accuracy and correlation between this and the manual method. Methods: We prospectively analyzed 150 CSF samples from dogs using the Sysmex XN-V BF module and compared the results with those obtained using the manual counting method. We also evaluated the linearity, detection limits, and imprecision of the Sysmex XN-V BF module. Results: The Sysmex XN-V BF module analyzer performance had a sensitivity of 92.59% and specificity of 94.30%. The lower limit of quantification for the total nucleated cell count (TNCC) was 0 cells/μL. A Pearson´s correlation coefficient of 0.945 was found between both methods for TNCC, with 0.997 and 0.940 for samples with TNCC >10 cells/μL and TNCC >5 cells/μL, respectively. The correlation coefficient for the mononuclear and polymorphonuclear differential cell count was −0.031 and −0.019, respectively, and it was 0.576 for the RBC count. Conclusions: The Sysmex XN-V BF module provides reliable TNCCs for canine CSF, even for samples with low cell numbers, but manual cytologic evaluation is still needed for differential cell counts.