9/10/2023 0 Comments Scatter gram![]() Clumped RBCs was counted as a single cell resulting in spuriously high MCV. The high MCV initially recorded by the automated counter was due to the RBC clumping by cold agglutinins. Patient in case 6 had infectious mononucleosis complicated by cold agglutinin haemolytic anaemia. The additional peak seen initially disappeared. Ī) RBC histogram of case 6 showing an additional small peak at 180 fL region b) RBC histogram of case 6 when the same blood sample was warmed to 37☌ and reanalysed. His Hb was 6.6 g/dl, WBC count was 41,500 per mm 3, and platelet count was 20,000 per mm 3. Ĭase 4: A 63-year-old male came to Outpatient Department (OPD) with tiredness and intermittent fever. The differential diagnoses for spurious elevations of the WBC count are platelet clumps, nucleated RBCs, incomplete lysis of RBCs, cryoglobulins, and cryofibrinogen, all of which may be wrongly counted as WBC by the haemanalyser. Insufficient lysis of RBCs due to the lack of stromatolyser solution resulted in the entry of RBCs into the WBC counting block, causing a spuriously high count. This indicates a technical error in counting, which in this case was caused due to an empty stromatolyser bottle in the analyser machine. The histogram here shows a sliding curve that does not correspond to the usual WBC distribution. The WBC count in case 3 was 3.49 million per mm 3, which is in the range of RBC count. The sizing and counting of blood cells is based on this measurable change in the electrical impedance.Ī) WBC histogram of case 3 showing sliding curve b) Empty bottle of stromatolyser solution is seen when the outer cover of the analyser was opened. The passage of cells through the current changes the impedance between the terminals (Coulter principle). ![]() Cells are counted by passing a dilute solution of the blood through an aperture across which an electrical current is flowing. The size of the WBCs after lysis corresponds to the size of their nuclei hence neutrophil is the largest after lysis even though originally monocyte is the largest WBC. After lysis, only the nuclei of the WBCs along with a thin rim of cytoplasm remains, which are counted and plotted in the WBC histogram. This solution is composed of an organic quarternary ammonium salt (8.5 g/L) and sodium chloride (0.6 g/L). All the red cells in the blood directed towards the WBC counting block are lysed first using the stromatolyser solution. ![]() RBCs and platelets are counted in the same block whereas, WBCs are counted in a separate block. There are three detector blocks in an automated haematology analyser. The automated blood cell counting process is very fast and can process up to 60-80 blood samples in an hour. Principle of Automated Haematology Analyser ![]()
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