Laboratory Investigation of the Full Blood Count & WBC disorders

Question 1

How does normal haemopoiesis occur (RECAP)

Answer 1

• Produced in the bone marrow of long bones and mature within peripheral blood
• Starts with multipotent stem cells which divide to self-renew themselves and become either myeloid or lymphoid stem cells in response to growth factors.
• Lymphoid stem cells give rise to T cells, B cells and natural killer cells
• Myeloid stem cells give rise to: megakaryocytic and platelets, Erythrocytes, basophils, neutrophils, eosinophils and monocytes

Question 2

What do we look for in a Full blood count for red blood cells?

Answer 2

• Hb: concentration of Haemoglobin
• Hct: Percentage of blood volume as RBC
• MCV: Average size of RBC
• MCH: Average haemoglobin content of RBC
• RDW: Range of deviation around RBC size
• Reticulocyte count
• Blood film

Question 3

What do we look for in a Full blood count for white blood cells?

Answer 3

• Total WBC and differential
• Neutrophils, lymphocytes, monocytes,
• basophils, eosinophils

Question 4

What do we look for in a Full blood count for platlets

Answer 4

Platelet count and size

Question 5

What morphological indicators do we look for in a FBC for RBC

Answer 5

• Size – big or small - anisocytosis
• Colour – Hb content
• Shape: round, TDP, irregular, elliptocytes - poikilocytosis
• Polychromasia
• Inclusions

Question 6

What morphological indicators do we look for in a FBC for WBC

Answer 6

• Numbers – too many, too few
• Normal morphology – dysplastic features
• Immature cells – myelocytes, precursors,
• Abnormal Cells – blasts, atypical lymphoid cells
• Inclusions

Question 7

How do we process full blood counts

Answer 7

FBC processed using optical scatter methods and presented in cytogram where population of cells are displayed in distinct cluster.

If the differentials are not displayed correctly, this alerts operator to refer the sample for a blood smear to be examined; as shown on left of cytogram with immature granulocytes in the neutrophil region

Question 8

What are the advantages of using a haematology analyser to do FBCs

Answer 8

• Efficient and cost effective:
  processing of large number of samples.
• Accuracy and precision of quantitative blood test
• Ability to perform multiple test on single platform
• Reduced labour requirements
• Invaluable for accurate determination of red cell indices; e.g. MCV

Question 9

What are the disadvantages of using a haematology analyser to do FBCs

Answer 9

• Flagging of laboratory test results demand labour intensive manual examination of blood smear.
• Comments on red cell morphology cannot be generated.
• Platelet clumps are counted at single, so low count.
• Expensive with high running cost

Question 10

Lecture Slides have blood film pictures for each condition

Answer 10

Lecture Slides have blood film pictures for each condition