Haematology: Lab Investigation of The FBC

Question 1

What measures of red blood cells are included in a full blood count?

Answer 1

• Haemoglobin (Hb): Concentration of Haemoglobin
• Hematocrit (Hct): Percentage of blood volume as RBC
• Mean cell volume (MCV): Average size of RBC
• Mean cell haemoglobin (MCH): Average haemoglobin content of RBC
• Red blood cell distribution width (RDW): Range of deviation around RBC size
• Reticulocyte count
• Blood film

Question 2

What measures of white blood cells are included in a full blood count?

Answer 2

• Total White blood cell count
• Neutrophil count
• Lymphocyte count
• Monocyte count
• Basophil count
• eosinophil count

Question 3

What measures of platelets are included in a full blood count?

Answer 3

• Platelet count and size

Question 4

For red blood cells what characteristics can a blood film show?

Answer 4

• Size – big or small - anisocytosis (when RBCs are unequal in size)
• Colour – Tells you about Hb content
• Shape - Round, TDP, irregular, elliptocytes (elipsis shaped) or poikilocytosis (abnormally shaped)
• Polychromasia - Abnormal number of reticulocytes in blood
• Inclusions - Things within RBCs

Question 5

How can Polychromasia be identified using blood film?

Answer 5

• Reticulocytes are bigger than mature red blood cells
• They don’t have an area of central pallor
• They also contain a small amount of RNA, unlike mature RBCs, which means they appear more purple on blood film comapred to RBCs as they stain in a slightly different way

Question 6

For white blood cells what characteristics can a blood film show?

Answer 6

• Numbers – too many, too few
• Normal morphology
• Immature cells – e.g. myelocytes, precurors,
• Abnormal Cells – e.g. blasts, atypical lymphoid cells
• Inclusions

Question 7

Blood test tubes have different coloured tops as shown by the image below. Each coloured top represents a different use for that bloos sample. Name some of the different colur tops and the uses for the blood samples they represent.

Answer 7

• Purple top - Used for full blood count samples as tube contains EDTA which stops clotting
• Yellow (rust) top - Used for renal function/electrolyte tests as tube has gel on bottom which causes clotting to occur
• Turquoise top - Tube contains citrate which is an anti-coagulent, stops clotting, and is used in blood clotting tests
• Pink top - Also contains EDTA and is used for blood transfusions and crossmatching donor and patient samples
• Grey top - Contains glucose