Accuracy and Precision Study: Body Fluid White Blood Cell (WBC) Analysis (Peritoneal, Pleural and Peritoneal Dialysate) Using a Light Scatter Technology (ADVIA^®2120/2120i) Versus Hemocytometer Manual Counts

The ADVIA^® 2120/2120i body fluid application is an in vitro diagnostic test for the enumeration of the total nucleated cell (TNC) or white blood cell (WBC) count and RBC (red blood cell) count for pleural, peritoneal and peritoneal dialysis (PD) specimens collected in K₂ EDTA. Total nucleated cell (TNC) and RBC counts are used in the laboratory assessment of these fluids. The TNC count is an absolute count of the nucleated blood cells, mesothelial cells, and other non-hematopoietic cells in these fluids.

The objective is to demonstrate concordance between the manual (hemocytometer) method versus the light scatter principle used on the ADIVA^® 2120i analyzer.

The ADVIA^® 2120/2120i Body Fluid Application uses the Basophil/Lobularity and RBC/PLT channels to enumerate the WBC and RBC counts. WBC counts are derived from the Basophil/Lobularity channel by a process in which the cytoplasmic membrane is stripped and the suspension of cells is intercepted by light from the laser diode where the low-angle light scatter (2° to 3°) and high-angle light scatter (5° to 15°) signals of each cell are counted. The manual method uses a hemocytometer in which a chamber is charged with fluid and both areas of the chamber are counted and the result averaged. De-identified remnant peritoneal, pleural and peritoneal dialysate samples were processed within 2 hours in the Hematology Laboratory according to their standard operating procedure. Samples with TNC counts that fell in the range of 0.030 to 400 × 10³ cells/μ L (30 to 400,000) for each type of fluid were included. Ten consecutive runs were performed for each type of fluid to determine precision.

The WBC reproducibility study (n=10) demonstrates that within the run, precision of the body fluid counts demonstrates a coefficient of variation (CV) ≤ 10 CV. Regression analysis (n=34) demonstrates an r=.93 using samples across the reportable range.

These results suggest that the light scatter technology used on the ADVIA^® 2120/2120i gives both accurate and precise WBC determinations and compares very well to the manual method for determination of WBC analysis in peritoneal, peritoneal, dialysate, and pleural fluids. Utilizing this method will decrease turn-around time for this process, resulting in a faster time to result and ultimately better patient outcomes.

Castellone:Siemens Healthcare: Employment. Canfield:Siemens: Employment. Kling:Siemens: Employment.