Original Article Performance Evaluation of Hematology Analyser Sysmex KX – 21 for Platelet and WBC Count Muneeza Natiq,1 Rabia Ahmed,2 Noshin Wasim Yusuf3 Abstract RBCs and lyze resistant RBCs (indicated by respective flags on Sysmex KX – 21). 262 (17.9%) samples mis- Objective: To evaluate the performance of Sysmex sed differential count on automated analyser, due to KX – 21 for the estimation of Platelet and WBC count low count or high count with immature cells and nor- in comparison with microscopy. mal count with immature cells. Differential of rest of Study Design: It is prospective cohort study. the 1196 (82.1%) samples also matched the manually Place and Duration: It was conducted in the Patho- done differential count. Regarding platelets, 1435 logy department, Allama Iqbal Medical College, from th th (98.4%) samples matched the platelet count on peri- 7 Oct. 2009 to 6 Nov. 2009. pheral smear. 23 (1.6%) samples didn’t correlate with Materials and Methods: Out of the total 1500 samp- the smear due to platelet clumps and fragmented RBCs les, 1458 (97%) samples after exclusions were finally (indicated by respective flags on Sysmex KX – 21). evaluated for the study. On each sample, automated Conclusion: Sysmex KX – 21 is a reliable automated blood cell count was performed using Sysmex KX – analyser for total WBC and platelet count while re- 21 and the results were compared by peripheral smear evaluation by peripheral smear is only required for examination for Platelet count, WBC count and its dif- those samples where the automated analyser indicates ferential. The samples were from Medicine, Pediatrics with flagging. and Oncology wards only. Non-toxic, biodegradable reagents. Results: Out of 1458 samples, WBC count of 1452 Reliable hardware and results. (99.5%) samples matched the total count on peripheral Network capability via your LIS. smear examination. 06 (0.5%) samples showed spur- Key words: Sysmex KX – 21, microscopy, WBC ious WBC count due to the presence of nucleated count, platelet count. Natiq M.1 Introduction Assistant Professor Pathology (Hematology) Allama Iqbal Medical College (AIMC), Lahore Traditionally, the blood counts were performed man- ually using the hemocytometers. The differential leu- 2 Ahmed R. kocyte counts were done by studying the peripheral Assistant Professor Pathology (Hematology) blood smears (also referred to as the 100 – cell slide Allama Iqbal Medical College (AIMC), Lahore differential, eye count leukocyte differential or manual Yusuf N.W.3 counts). For manual method, experience is needed to Professor and Head, Department of Pathology make technically adequate smears consistently. There Allama Iqbal Medical College (AIMC), Lahore is non-uniform distribution of red blood cells and ANNALS VOL 18. NO. 3 JUL. – SEP. 2012 300 PERFORMANCE EVALUATION OF HEMATOLOGY ANALYSER SYSMEX KX – 21 FOR PLATELET AND WBC COUNT WBCs over the smear. It is subjective, time consum- prospective cohort study. Routine samples from medi- ing, labor – intensive, and statistically unreliable (only cine, oncology and pediatric wards were received in 100 – 200 cells are counted).1 EDTA vacuotainers and analyzed within 4 hours of The increasing workload experienced by many receiving. Low volume, high volume and clotted sam- hematology laboratories coupled with the reduction in ples were excluded from the study. CBC was perfor- staff numbers lead to the introduction of automated med using Sysmex KX – 21, that was maintained and hematology analysers. The automated hematology calibrated as recommended by the manufacturer. Qua- analyzer with complete blood count (CBC) results has lity Control was maintained by running controls daily replaced the traditional manual or individual assay and maintaining Levey – Jenings Chart. Air dried blo- methods for haematological parameters and the eye od smears were made, stained by Giemsa stain and count leucocyte differential as the initial screening and examined under Microscope. Manual WBC Count was detection system for haematological abnormalities in done by calculating estimation factor and then multi- modern hospitals and clinics.2 Cell counting with these plying this estimation factor with average manual instruments is rapid, objective, statistically significant WBC Count per field. Manual Platelet Count was done (8000 or more cells are counted), and not subject to the by counting number of Platelets in 10 successive high distributional bias of the manual count. They are also power fields, calculating their average and multiplying more efficient and cost effective than the manual me- it by 10.9 The data is presented as frequency tables, thod. Some of these cell counters can process 120 – charts and graphs. 150 samples per hour.1 Sysmex KX – 21 is a discrete hematology analyzer designed for high – volume testing in clinical labora- Results tories. It is an automatic multiparameter blood cell counter for in vitro diagnostic use in clinical labora- A total of 1500 samples of CBC were received during tory. It employs impedence technology for counting of this duration. Out of these, 1458 (97%) samples were red and white cell and platelet count. It provides a processed and 42 (3%) were rejected. Among rejected CBC with 17 reportable parameters and 3-part WBC samples, 20 (47%) were low volume, 10 (23%) were Differential, which includes an Absolute Neutrophil high volume and 12 (28%) samples were clotted. Count (ANC). The results include histograms for The comparison of the WBC count of the samples WBC, RBC and PLT. For the detection of hemoglo- processed by the two methods revealed that 1452 sam- bin, it uses cyanide free method that does not pollute ples showed the same results while 06 samples showed the environment.3 discrepant results. This is shown by the figure 1. Although it has adequate reproducibility, there are The peripheral smear of the samples showing dis- concerns over accuracy. It may produce cell counts crepant results for WBC count revealed lyze resistant which are falsely increased or decreased. Falsely low platelet count can be given by analyser due to platelet clumping. But these discrepancies are mostly indicated 1600 by ‘flags’ which are warnings generated and displayed 1400 by the machine to alert the laboratory personnel that the machine has detected some abnormality in cell 1200 population or distribution that needs attention. This 1000 study evaluated the performance evaluation of Sysmex 800 Series 1 kx – 21, comparing the results of WBC count, its dif- 600 Series 2 ferential and platelet count with and without flags on 400 Sysmex kx – 21 with microscopy. 200 0 Material and Methods Series 1 Series 2 This study was conducted in the Pathology Depart- Series 1: No. of samples with same results n = 1452 (99.5%) ment of Allama Iqbal Medical College, Lahore from Series 2: No. of samples with same results n = 06 (0.5%) 7th October, 2009 to 6th November, 2009. It is a Figure 1: WBC Count Estimation. 301 ANNALS VOL 18. NO. 3 JUL. – SEP. 2012 MUNEEZA NATIQ, RABIA AHMED, NOSHIN WASIM YUSUF RBCs and nucleated RBCs in 03 samples each as Correlation of the differential count given by sys- shown in figure 2. mex kx – 21 and peripheral smears showed the follow- ing results (Table 1). The sysmex missed the differential of about 262 samples due to following reasons (Table 2). 3 The comparison of the platelet count of the sam- 2.5 ples processed by the two methods revealed that 1435 samples showed the same results while 23 samples 2 showed discrepant results as shown in figure 4. Series 1 1.5 Series 2 1 1600 0.5 1400 1200 0 Series 1 Series 2 1000 Series 1 Series 1: Lyze – 1 Resistant RBC’s, n = 03 (50%) 800 Series 2 Series 2: Nucleated RBC’s, n = 03 (50%) 600 Figure 2: Reason for Discrepant Results. 400 200 When the differential count estimation was done, 0 Series 1 Series 2 it was found that the sysmex gave the differential of about 1196 samples while it missed the differential of Series 1: No. of Samples with Same Results about 262 samples. It is shown in figure 3. n = 1435 (98.4%) Series 2: No. of Samples with Disc repant Results n = 23 (1.6%) Figure 4: Platelet Count Estimation. 1200 1000 Out of these 23, 17 samples showed platelet clum- 800 ping while 06 samples showed fragmented RBCs on peripheral smear (Table 3). 600 Series 1 Series 2 400 Discussion 200 In WBC count estimation, 99.5% samples correlated 0 well with manual WBC Count. Ike et al described that Series 1 Series 2 the two methods of WBC counting correlated posi- 2 Series 1: Differential given by Sysmex n = 1196 (82.1%) tively. 0.5% of the samples showed discrepant results Series 2: Differential not given by Sysmex n = 262 (17.9%) due to lyze resistant RBCs and nucleated RBCs indica- ted by respective flags on Sysmex. Hanse et al descri- Figure 3: Differential by Sysmex KX 21. – bed that the correlation between the automated flagged Table 1: Correlation of differential Count between Sysmex and Smear. Total No. of Differential Given by No. of Smears correlating with No. of Smears not correlating with Sysmex Sysmex Sysmex 1196 1186 (99.1%) 10 (0.9%) ANNALS VOL 18. NO. 3 JUL. – SEP. 2012 302 PERFORMANCE EVALUATION OF HEMATOLOGY ANALYSER SYSMEX KX – 21 FOR PLATELET AND WBC COUNT Table 2: Causes of Missing differential Counts. Low WBC Low WBC Count Normal WBC Count High WBC Count Old Total Samples Count with Abnormal cells with Abnormal cells with Abnormal cells Samples 262 122 (46.5%) 09 (3.4%) 38 (14.5%) 68 (25.9%) 25 (9.5%) Table 3: Causes of Discrepancy in Platelet Count. smear may avoid erroneous diagnosis of thrombo- cytopenia.9 Nishiyama M et al described fragmented Total Samples Platelet Clumping Fragmented RBCs red cells as the major cause of spuriously high platelet 23 17 (73.9%) 06 (26.1%) count.10 and manual results was excellent.4 Conclusion Differential count given by Sysmex KX – 21 also The results of the present study confirm that counting showed very good correlation (99.1%) with the man- performance by Sysmex KX – 21 is robust and clini- ually done differential.