Correlation between Morphological Typing of Anemia Based On RBC Indices and RDW Obtained from Sysmex KX-21, an Automated Hematological Analyser with Peripheral Blood Smear Examination

INTRODUCTION - Anemia affects millions of people globally. Once anemia is diagnosed clinically, a morphological typing of anemia pathologically helps the treating physician to come up to the cause of anemia. In the new era of laboratory diagnostics, the automated hematology analyzers give accurate results for the RBC indices and hence have replaced the manual methods in the majority. The expertise needed to see the peripheral blood smear is unquestionably far more than that needed to run the analyzers. Moreover, in morphological typing of anemia based on peripheral blood smear examination, there is intra and inter observer variation. Further peripheral blood smear review performed by pathologists hardly ever provide unique information and provide incremental helpful information in few of the cases. Hence, the aim of the present study was to correlate morphological typing of anemia based on RBC indices and RDW obtained from KX-21, an 3 –part automated hematology analyzer with peripheral blood smear evaluation and to discover if the rate of manual peripheral blood smear review in cases of anemia already morphologically typed on automated analyzer can be reduced. METHODS - A total of 1100 cases of anemia were studied over a period of five years between January 2017 to December 2021 at Central Diagnostic Laboratory, Dhiraj hospital, Department of Pathology, Smt. B. K. Shah Medical Institute & Research Centre, Piparia, Vadodara. Anemia typing was done by two methods – to start with using RBC indices & RDW only. Subsequently on peripheral blood smear examination. The results were then correlated and analyzed. RESULTS - All the cases were typed as Microcytic Hypochromic Anemia with normal and raised RDW, Macrocytic Anemia and Normocytic Normochromic Anemia with normal RDW (91.82 %) on RBC indices with RDW alone. Then all these were confirmed as the same by peripheral blood smear examination. However all cases typed as Normocytic Normochromic Anemia with raised RDW (8.18 %) on RBC indices with RDW alone were typed as either Dimorphic Anemia or Microcytic Hypochromic Anemia with polychromasia on subsequent peripheral blood smear examination. CONCLUSION - Morphological typing of anemia in cases of Microcytic hypochromic anemia with normal and raised RDW and Macrocytic anemia using RBC indices and RDW from 3 part automated hematology analyzer shows very high specificity and high sensitivity. In cases of Normocytic normochromic anemia, the cases with normal RDW showed high specificity and sensitivity but the cases with high RDW were wrongly typed on indices alone and had a low sensitivity and specificity signifying that additional peripheral blood smear examination as an extremely essential tool in morphological typing of anemia