DIAGNOSTIC UTILITY OF RED BLOOD CELL HISTOGRAM ANALYSIS FOR MORPHOLOGICAL CLASSIFICATION OF ANAEMIA: A COMPARATIVE STUDY WITH PERIPHERAL BLOOD SMEAR IN A TERTIARY CARE CENTER

Abstract

Background Accurate morphological classification of anaemia is fundamental for identifying its underlying cause and guiding appropriate management. Although peripheral blood smear (PBS) examination remains the reference standard, it is labor-intensive and requires experienced personnel. Automated haematology analyzers routinely generate red blood cell (RBC) histograms, but their diagnostic value is often underutilized. This study evaluated the diagnostic performance of RBC histogram patterns compared with peripheral blood smear morphology for classifying anaemia. Methods A hospital-based observational cross-sectional study was conducted among 216 adult patients with hemoglobin concentrations below 10 g/dL at a tertiary care center in Punjab, India, between July 2024 and December 2025. EDTA blood samples underwent automated complete blood count analysis with RBC histogram generation and simultaneous Leishman-stained peripheral blood smear examination. Peripheral smear morphology served as the reference standard. Associations between histogram patterns and smear findings were assessed using the Chi-square test, while diagnostic indices including sensitivity, specificity, predictive values, likelihood ratios, and overall accuracy were calculated with 95% confidence intervals. Results The mean age of participants was 53.7 ± 17.0 years, and females constituted 59.3% of the study population. Peripheral blood smear identified dimorphic anaemia (44.4%) as the most frequent morphological subtype, followed by microcytic hypochromic anaemia (40.7%), normocytic normochromic anaemia (13.0%), and macrocytic anaemia (1.9%). The predominant histogram pattern was a left-shifted curve (40.7%). A highly significant association was observed between RBC histogram patterns and peripheral smear morphology (p 0.001). Left-shifted histograms accurately identified microcytic hypochromic anaemia with 81.8% sensitivity and 85.2% diagnostic accuracy. Combined broad-based and bimodal histograms demonstrated 94.3% sensitivity for dimorphic anaemia, and excellent specificity of 95.1% in normal curve whereas right-shifted histograms achieved 100% specificity and 99.5% overall diagnostic accuracy for macrocytic anaemia. Conclusion RBC histogram analysis demonstrates excellent agreement with peripheral blood smear morphology and provides a rapid, objective, and cost-effective approach for the preliminary morphological classification of anaemia. Routine interpretation of histogram patterns during complete blood count analysis may facilitate early diagnostic decision-making, optimize laboratory workflow, and reduce unnecessary peripheral smear examinations, particularly in resource-limited healthcare settings.

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Issue

Vol. 97 No. 1 (2026)