The incidence of pseudothrombocytopenia in automatic blood analyzers.

Unlabelled: The aim of the present work was to undertake an assessment of the incidence of pseudothrombocytopenia (PTCP) in patients referred for evaluation of thrombocytopenia in an outpatient hematology clinic.

Methods: Prospective assessment of 60 consecutive cases with platelet count < 100 x 10(9)/l in a hematology clinic during a 2-year period.

Results: PTCP was the second most common cause for low platelet count, with an incidence of 17%. Platelet count of patients with PTCP at presentation was 42 +/- 22 x 10(9)/l, and when re-analyzed on fresh samples, 208 +/- 39 x 10(9)/l. The relatively high prevalence of pseudothrombocytopenia in our series was due to a lack of microscopic inspection of the blood smear in the primary care laboratories and considerable delay in sample processing.

Conclusions: PTCP should be considered in the assessment of low platelet count. While decreasing the transfer time of blood specimens may decrease PTCP incidence, microscopic inspection of the blood smear may avoid erroneous diagnosis of thrombocytopenia.