An Evaluation of Nucleated Red Blood Cell Count by an Automated Haematology Analyser- A Tertiary Centre Experience.

ABSTRACT

nRBCs also referred to as normoblasts are seen in the peripheral blood films invariable numbers; both in physiological as well as pathologic states. Enumeration ofthese cells by modern day automated analysers remains a challenge. We wanted toassess the precision of the Beckman Coulter LH 755 & 780 haematology analysersTMin enumerating the nRBC count.METHODSThis is a retrospective study conducted in the Clinical Laboratory and HaematologyDivision of Kasturba Hospital, Manipal over a 3-month period on the BeckmanCoulter LH 755 & 780 haematology analysersTM (Beckman Coulter Inc., Miami, FL,USA) after obtaining requisite clearance from the Institutional Ethics Committee. Adata of 47,332 random blood samples run on the analysers was collected. Bothdescriptive and analytical statistics were performed using the SPSS softwareversion 22.0TM (Chicago, IL, USA). The sensitivity, specificity and kappa agreementwere calculated using the same.RESULTSA total of 797 cases from the 47,332 samples showed a “flag” for nRBCs. TwoTwenty of these cases were confirmed microscopically to have had nRBCs in theperipheral smear (true positives). 137 cases had nRBCs in the smear but were notdefinitively evaluated by the instrument (false negatives). A vast majority of thecases (577) did not reveal any nRBC on microscopic examination despite a flaggenerated by the machine (false positives). Additionally, a sensitivity of 27.6% andspecificity of 99.7% were also noted. The kappa agreement was 0.376 whichshowed a fair agreement between the two methods.CONCLUSIONSThe automated haematology analysers Beckman Coulter LH 755 & 780 were foundto be less sensitive in adequately enumerating the nucleated red blood cells. Thenumber of false positives can be reduced by noting the ‘cellular interference’ flag. Amanual review of such smears is necessary to confirm or refute such instrument