Insights from Histogram and Flag Analysis in Pseudothrombocytopenia Cases: A Single-centre Cross-sectional Study

Introduction: Pseudothrombocytopenia (PTCP), also known as Spurious Thrombocytopenia (TCP), is a common problem encountered in many laboratories. When stable patients are evaluated for thrombocytopenia, the first step is to exclude PTCP. Most haematology analysers are equipped with softwaregenerated flagging algorithms that identify abnormal platelet distributions, indicating the presence of giant platelets or platelet clumping, which is reflected in the histogram. Aim: To analyse the White Blood Cell (WBC) and platelet histograms in cases showing falsely low platelet counts. Materials and Methods: This cross-sectional study was conducted in the Department of Pathology, Chettinad Hospital and Research institute, Tamil Nadu, over a period of six months from January 2021 to June 2021. Haemogram samples were analysed using the Beckman Coulter LH 750 analyser within two hours of sample collection. Samples showing platelet counts of less than one lakh (1,00,000/μL) on the analyser were further evaluated using Leishman-stained peripheral smears to confirm platelet counts. All cases that showed low platelet counts on the analyser but adequate platelet counts on the peripheral smear were included in the study. Demographic details such as age and sex were recorded. Platelet and WBC histograms, along with platelet parameters such as Mean Platelet Volume (MPV) and Platelet Distribution Width (PDW), were analysed. The results were tabulated using Microsoft Excel, and mean and median values were calculated. Results: In this study, PTCP cases constituted 0.32% of the total cases (18,654) and 1.96% of thrombocytopenic cases (3,060). Among the 60 identified PTCP cases, 44 were males (73%) and 16 were females (27%), giving a male-to-female ratio of 2.75:1. The study population ranged from 19 to 73 years of age, with a mean age of 45±15.11 years. MPV was within normal limits in 40 cases, increased in 15 cases, and decreased in five cases. PDW was increased in 43 cases and normal in 17 cases. Platelet histograms showed changes such as the presence of Multiple Peaks (MP flag) in 41 cases (68.3%). In WBC histograms, platelet clumping was identified by an abnormal curve in front of the lower discriminator in 53 cases (88.3%). Conclusion: Microscopic blood smear examination in cases of PTCP along with analysis of histogram can prove to be valuable tool to provide the details of the etiology and pathogenesis of PTCP.