Recognition and prevention of pseudothrombocytopenia and concomitant pseudoleukocytosis

Unrecognized anticoagulant-induced platelet (PLT) aggregation, leading to pseudothrombocytopenia and concomitant pseudoleukocytosis, can have serious clinical consequences. It can be readily recognized by inspecting conventional blood smears or the white blood cell histograms generated by modern blood cell counters. Blood specimens from twenty patients with known EDTA-induced platelet aggregation were consecutively drawn into three other anticoagulants (using Vacutainer tubes) and processed in a three-part differential Coulter Counter S Plus IV. PLT aggregation is shown to be generally induced by Li-heparin but much less frequently by citrate solutions. Prevention is almost invariably achieved by acid citrate dextrose (ACD). To that end approximately 2.5 mL of sterile ACD was aseptically injected beforehand through the stoppers of plain 5 mL Vacutainer tubes without breaking the vacuum. After blood drawing, correction for dilution was made by comparing hemoglobin values in EDTA and ACD.