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Figure 1. Pseudothrombocytopenia.
An electronic counting machine estimated the platelet count in a routine blood sample, anticoagulated with EDTA, at 44,000 per cubic millimeter. A peripheral-blood smear (Wright's stain, x800) from the same blood sample (Panel A) shows three typical platelet clumps, each containing 20 to 30 platelets, which were misidentified by the machine as white cells. When a second blood sample from the same patient was anticoagulated with heparin, which prevented in vitro clumping and maldistribution of the platelets (Panel B; Wright's stain, x800), the machine read the patient's true platelet count of 560,000 per cubic millimeter. This example . . . [Full Text of this Article] |
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