Platelets clumps. EDTA Pseudothrombocytopenia is a laboratory artifact that can occur when EDTA (ethylenediaminetetraacetic acid), a chelating agent commonly used to preserve blood samples and prevent coagulation, is present in the blood sample at the time of platelet counting. EDTA can cause platelets to clump together, leading to an underestimation of the true platelet count. This can have significant clinical implications, as a falsely low platelet count may lead to inappropriate treatment de