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Preparation and Examination of Blood Smear (view source)
Revision as of 16:16, 11 April 2022
, 16:16, 11 April 2022no edit summary
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== Haematology general comments and selected techniques ==
=== Sampling ===
Anticoagulated blood is required for cell counts. If there are any visible clots, even small ones, the sample is discarded, as the WBC and platelet counts will be inaccurate. EDTA is the best anticoagulant to preserve cell detail but this does not provide such good cell morphology as a well prepared fresh smear. Heparin can be used but produces poor staining of cells. EDTA tubes should be completely filled to the level indicated. An excess of EDTA causes red cell shrinkage and decreased PCV. Overfilling may lead to clotting. Blood should be analysed within 2-3 hours or kept refrigerated. After 6-24 hours storage, RBCs swell leading to increased PCV and MCV with reduced mean corpuscular haemoglobin concentration (MCHC). Other red cell indices are not affected.
Artefactual changes may result from excess suction on the syringe, over zealous agitation of the EDTA tube and high environmental temperatures, which can all cause haemolysis. Sample ageing also increases the likelihood of haemolysis. Samples submitted to the laboratory should arrive within 2 days. Delays often result in cell deterioration and lysis, therefore submission of a fresh smear is advisable.
== Preparation of Blood Smear ==
== Preparation of Blood Smear ==