Artifactual changes in equine blood following storage, detected using the Advia 120 hematology analyzer

Background - Delayed analysis of blood samples may be caused by restricted access to laboratories. Artifactual changes may occur in the measured analytes as a consequence of delayed analysis and may complicate interpretation of the data. Objective - The purpose of this study was to characterize artifactual changes in equine blood, due to storage, using the Advia 120 hematology analyzer. Methods - Samples of blood from 5 horses were analyzed using the Advia 120 soon after collection and again after 24 and 48 hours of storage at either 4°C or ambient laboratory temperature (∼24°C). Results - Delayed analysis of equine blood samples resulted in increased numbers of normocytic hypochromic RBCs, increased numbers of macrocytic hypochromic RBCs, misclassification of granulocytes as mononuclear cells using the basophil reagent method, and pseudothrombocytosis, due to misclassification of ghost RBCS as platelets. The latter artifact was corrected by an amended version of the software. Many of the artifactual changes were identified by morphology flags. Conclusion - Characteristic changes in cytograms produced by the Advia 120 allowed recognition of artifactual changes in stored equine blood samples. These changes were less pronounced in samples stored at 24°C than at 4°C