Thrombocytopenia and edges of the smear - keep your eyes peeled.

Sir,

The reports of thrombocytopenia elicit a knee jerk to the practitioners and make them search for a cause. Rarely analytical error has been considered. We present one such report, emphasizing the importance of examining the terminal edge of a smear. The widespread use of automated hematology analyzer has replaced the traditional manual method because of rapid, cost effective and dependable results. However, spurious results are observed at times due to agglutination of platelets in the smear prepared from the blood sample collected with an anticoagulant ethylenediamine tetra-acetic acid (EDTA).[1] Usually analyzer will turn on the signals to alert the technician, during extreme results. We had noted thrombocytopenia in a healthy middle-aged male without any co- morbidities during the routine health check up for whom any alarming signs were present. Careful inspection of the blood smear revealed massive platelet clumps exclusively found at the edges of the smear. A repeat smear of the same patient made from heparinized blood sample revealed a normal platelet count and distribution. EDTA-induced pseudothrombocytopenia is aggravated, as evident from the illusionary microscopic findings of massive clump exclusively noticed at the lateral edges of the smear [Figure 1]. Bowen et al,[2] had reported that large clumps in the feather edge of the smear were missed in the routine slide review. Lombarts et al,[3] had emphasized to examine the edges of the smear since the clumps may migrate to the edges. This report including picture is presented in order to create awareness among physicians and laboratory personnel to exclude the possibility of pseudothrombocytopenia and thereby avoid inappropriate diagnostics and decisions.

Figure 1

Peripheral smear shows large platelet clumps exclusively found at the edges of the smear. Only very few single platelets were seen in the actual examination field of the smear