Blood films

Question 1

how is the normal range for a measure decided?

Answer 1

• leaves out 2.5% normal values above range and 2.5% below range, including 95% of popn.
• • or - 1.96 standard deviations from mean.
• range changes with sex, age, ethnicity, co-morbidities.

Question 2

what are the steps of receiving pathology results and where might errors occur?

Answer 2

• specimen collection : specimen mix up, poor technique.
• delivering specimen to lab : delay, wrong delivery method.
• specimen analysis and reporting results : incorrect, technical error, mix up of specimen.
• responsive action : results reviewed wrong, wrong patient.

Question 3

what are the essential parameters of a full blood count?

Answer 3

• red cells & HB.
• platelet count.
• white cell count, full differential of neutrophils, eosinophils, basophils, lymphocytes, monocytes.

Question 4

name some full blood count analyser techniques.

Answer 4

• spectrophotometry : amount of light absorbed proportional to amount of compound within.
• flow cytometry : single file of cells, pass through light beam, scatter forward indicates size and more the scatter bigger the cell. side scatter indicates granules etc.

Question 5

define packed cell volume.

Answer 5

• proportion of blood made up of RBC, when centrifuged easier to visualise.
• assess anaemia, or more often polycythemia as PVC increased.

Question 6

how does microcytic anaemia and erthrocytosis affect red cell count?

Answer 6

• microcytic : iron deficiency anaemia reduced RCC, increased in thalassemia trait.
• erythrocytosis : if RCC elevated polycythaemia.

Question 7

differentiate between mean cell HB and mean cell HB concentration.

Answer 7

• MCH is an average measure of amount of Hb in each RBC whereas MCHC is the mean concentration of Hb in RBC.

Question 8

what is red cell distribution width used to assess?

Answer 8

• cause of anaemia.

Question 9

what does a high reticulocyte mean?

Answer 9

• precursors of mature RBC.

- increased in anaemias and decreased in bone marrow failure.

Question 10

define microlytic, macrolytic, hypochromic and hyoerchromic.

Answer 10

• microlytic : small RBC.
• macrolytic : large RBC.
• hypochromic : pale, less Hb.
• hyperchromic : dense and more Hb in given volume.

Question 11

define anisocytosis.

Answer 11

• increased variability in size.

Question 12

define dimorphism.

Answer 12

• two dinstinct popuation of RBC’s.

Question 13

define poikilocytosis.

Answer 13

• abnormally shaped RBC.

Question 14

define spherocytosis.

Answer 14

• spherical RBC.

Question 15

define eliptocytosis.

Answer 15

• elliptical RBC.

Question 16

what are howell-jolly bodies?

Answer 16

• erythrocytes with DNA/ nuclear fragments.

Question 17

what are heinz bodies?

Answer 17

• denatured haemoglobin.

Question 18

what might be some findings in blood during iron deficiency.

Answer 18

• Reduced Hb, MCV, MCH, MCHC.
• low or normal reticulocytes.
• increased red cell distribution width.
• hyperchromic on blood film.