Platelets are small, disc-shaped cellular components, typically measuring 1-3 μm in diameter, and appear purple with fine, irregular projections on their surfaces. When examining blood films prepared from non-anticoagulated samples, such as those obtained through direct fingerstick methods, platelets often cluster together. However, when platelet counts are assessed using automated blood cell counters with EDTA-anticoagulated samples, approximately 1% of individuals may exhibit falsely low counts due to the presence of EDTA-dependent antiplatelet antibodies. To prevent the misdiagnosis of thrombocytopenia in these cases, a parallel examination of a blood smear is recommended.
Box 1: Role of blood smear in thrombocytopenia
Blood smear analysis can indicate potential causes of abnormal platelet morphology, such as leukemia, microangiopathic processes like thrombotic thrombocytopenic purpura or disseminated intravascular coagulation, aplastic anemia, and rare conditions like May-Hegglin anomaly.
Occasionally, a phenomenon known as platelet satellitism can be observed, where platelets cluster around neutrophils. This occurrence is noted in individuals with platelet antibodies, though it can also be seen in otherwise healthy individuals. Analyzing a blood smear can be instrumental in identifying the underlying causes of thrombocytopenia, which may include conditions such as leukemia, lymphoma, or microangiopathic hemolytic anemia.
