Evaluation of blood smear Flashcards
What is the purpose of looking at blood smears?
Spot equipment errors
Find things that machines can’t, e.g.:
- Bands, metamyelocytes, toxic change
- nRBC’s, inclusions, parasites
- Red cell morphology (spherocytes, acanthocytes)
- Early red cell regeneration (polychromatophils)
Describe examination of a blood smear on low power
x10, x20
Identify 3 zones:
1. Feathered edge
- platelet clumps, big cells, big parasites
2. Body
- agglutination, rouleaux (RBCs stacking)
- generally don’t look here (cells clumped together)
3. Monolayer
- RBC density, WBC numbers
- best layer to look at
Describe examination of a blood smear on high power
x40, x100
Monolayer:
- platelet numbers & morphology
- RBC morphology
- small parasites
- WBC morphology and count
Look at all 3 cell series (RBC, WBC & platelets)
What section of a blood smear is this?
Feathered edge
(see platelet clumps & big cells)
What section of a blood smear is this?
Monolayer
(<50% of cells touching)
What section of a blood smear is this?
Body
(cells too close together to assess them)
What can be analysed about RBCs at x40-x100 magnification?
RBC morphology:
- anisocytosis (different sized RBCs)
- polychromasia (excess immature RBCs)
- poikilocytosis (abnormally shaped RBCs)
- inclusions (retained remnants of cellular components)
What can be analysed about neutrophils at x40 magnification?
Left-shift neutrophils (immature neutrophil inflammation)
Right shift neutrophils (hypermature)
Toxic change:
- vacuolation
- blue cytoplasm
- “Dohle” bodies
- septicaemias
What can be analysed about platelets at x40-x100 magnification?
Number – don’t expect spontaneous haemorrhage if >8-10 platelets per oil immersion field (averaged over several)
Size - bigger ones suggest active thrombopoiesis
Activated – may be associated with inflammation
What is this?
Stain precipitate
not bacteria (those would be more regular)
