EDTA-Dependent Pseudothrombocytopenia and Unnecessary Transfusion in a Patient with Crimean-Congo Haemorrhagic Fever

Thrombocytopenia is the major problem for management of Crimean-Congo haemorrhagic fever (CCHF) patients. Here we present a patient with CCHF who was treated for a misdiagnosis of refractory thrombocytopenia, whereas she had an ethylenediaminetetraacetic acid (EDTA)-dependent pseudothrombocytopenia. A 53-year-old female was transferred to our department on suspicion of CCHF. Laboratory findings included a platelet count of 1.7x103/mm3, a hemoglobin level of 11.3 gr/dL, and a white blood cell count of 3.3x103/mm3. Liver function tests and other biochemical findings were within normal limits. CCHF virus IgM antibody was positive. Since low platelet counts persisted despite transfusions consisting of four units of random donor platelets and four units of aphaeresis platelets for five days, refractory thrombocytopenia was suspected. Steroid therapy was started. Although blood smear examination was not initially performed because of the biologic hazard, persistent low counts of platelets were further evaluated by blood smear examination which revealed many platelet clumps. EDTA-dependent pseudothrombocytopenia was suspected for this normal appearance, and a repeated complete blood count using a citrated sample tube showed a platelet count within normal limits (i.e., 417x103/mm3). The patient was discharged after ten days in good health condition.