The Diagnostic Synergy of Automated Hematology and Manual Microscopy: An In-Depth Comparative Analysis of RBC Indices, Volume Histograms, and Peripheral Blood Smear Morphology in Adult Anemia

Abstract

Background: Morphological evaluation remains a cornerstone in the systematic diagnosis of anemia. Modern automated hematology analyzers provide rapid and standardized quantitative parameters, whereas manual peripheral blood smear (PBS) examination offers detailed qualitative assessment of red blood cell morphology.

Objective: To evaluate the diagnostic reliability and complementary utility of automated red blood cell (RBC) indices and RBC volume distribution histograms in comparison with manual PBS examination among adult patients with anemia.

Methods: A cross-sectional analytical study was conducted among 96 adult patients with anemia. Automated complete blood count parameters, including Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), Red Cell Distribution Width (RDW), and RBC volume histograms, were evaluated alongside blinded microscopic PBS examination. Kruskal-Wallis and Mann-Whitney U tests were used for comparison of numerical indices, while Pearson's Chi-square test was used to assess the association and concordance between RBC histogram patterns and PBS morphological classifications.

Results: Normocytic normochromic anemia was the predominant morphological subtype (64.6%, n=62), followed by microcytic hypochromic (27.1%, n=26), macrocytic (5.2%, n=5), and dimorphic (3.1%, n=3) patterns. Among the automated numerical parameters, MCV demonstrated statistically significant differences across the morphological categories (p<0.001). MCH, MCHC, and RDW did not demonstrate statistically significant differences (p>0.05). RBC volume histograms showed strong concordance with PBS morphological classifications (χ²=241.12, p<0.001), with an overall diagnostic agreement of 94.8% (91/96 cases).

Conclusion: RBC volume histograms, particularly when interpreted alongside MCV, provide a rapid and reliable screening approach for the initial morphological classification of anemia. Histogram analysis complements numerical RBC indices by providing a graphical representation of red cell volume distribution and may identify mixed or discrepant populations requiring targeted manual PBS examination. Automated parameters should therefore complement, rather than replace, microscopic smear evaluation.