Pseudo-thrombocytopenia (PTCP). A challenge in the daily laboratory routine?

Abstract Anticoagulation with ethylenediaminetetraacetic acid (EDTA) is a necessary pre-requisite for automated blood cell counting. With a prevalence of 0.01–1%, EDTA anticoagulation is accompanied by time- and temperature-dependent in vitro aggregation of platelets, resulting in false low counts. To avoid wrong clinical conclusions, spontaneous anticoagulant-induced platelet agglutination should therefore be recognized during analysis. This might be a challenge for the routine laboratory. The actual knowledge of this rare but clinically important laboratory artefact will be summarized and reviewed in the following, based on our own experiences and the available literature. This includes pathophysiological and epidemiological aspects, valuable information regarding the detection and prevention of a PTCP, and the possibilities for determination of the correct platelet count.