Evaluation of pre-dilution combined with optical/fluorescent platelet counting for correcting pseudothrombocytopenia

Pseudothrombocytopenia (PTCP), a common artifact in hematology, often leads to misdiagnosis and unnecessary interventions, with EDTA-dependent PTCP being the most frequent. Current corrective methods are limited by inefficiency and the risk of recurrence.

This study evaluated an integrated strategy-1:7 pre-dilution of fresh EDTA blood with optical/fluorescent platelet counting (PLT-O/PLT-F)-to correct PTCP caused by various factors. A total of 21 PTCP samples were analyzed using the impedance platelet counting method (PLT-I), conventional PLT-O/PLT-F, and pre-diluted PLT-O/PLT-F modes on Mindray BC-7500 CS and Sysmex XN20 analyzers, with manual counting (PLT-M) as the reference. Assessments included anti-interference efficacy: aggregation interference rejection (AIR), outlier rate (OR), and accuracy: recovery rate (RR), mean bias rate (MBR), root mean square error (RMSE), non-parametric bias analysis, and correlation/agreement tests.

Pre-dilution significantly improved anti-interference: DIL BC7500 PLT-O showed the highest AIR (95.24%) and the lowest OR (19.05%). Conventional modes showed significant negative bias, while pre-diluted modes eliminated bias, with RR within an acceptable range (90-110%) and low RMSE (23.15%). Non-parametric analysis showed no significant difference between DIL PLT-O/F and PLT-M (p > 0.05). Correlation and agreement were strong, with slopes near 1 and minimal bias. Bland-Altman analysis confirmed DIL BC7500 PLT-O had the smallest bias and best agreement with PLT-M.

Study limitations include a small sample size, single-center data, and testing only two analyzers. In conclusion, 1:7 pre-dilution with PLT-O/PLT-F effectively reduces platelet aggregation in PTCP, improves accuracy, anti-interference, and consistency, and offers a pilot solution for laboratory PTCP management. Further multicenter, large-scale studies are needed for validation.