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lecture 6 Flashcards

introduction to haematology (55 cards)

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1
Q

how is the haematological system assessed

A

packed cell volume, plasma protein, blood count, blood smear examination

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2
Q

what are the indications for assessment?

A

suspicion of: systemic inflammatory disorder, haemic neoplasia (leukaemia), anaemia, thrombocytopenia

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3
Q

where is blood sample taken?

A

jugular vein, to minimise damage to blood cells, only contraindication –> low platelet count (bleeding)

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4
Q

what needles

A

avoid small needles –> grren needle for dogs, blue for cats

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5
Q

predispositions before taking sample

A

clipping etc

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6
Q

what tube is preferred for haematology

A

EDTA –> chelates calcium, needed for clotting

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7
Q

citrate tube use

A

less platelet clumping in cats but not dogs

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8
Q

heparin tube use

A

poor staining of white blood cells (leukocytes) –> taking blood from small animal: can use the same sample for haematology

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9
Q

filling of tube

A

overfilling may allow clots to form, under-filling: altered red cell morphology, reduced packed cell volume, sample dilution

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10
Q

what if contaminate with EDTA?

A

artefactually increase potassium, decrease calcium levels

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11
Q

PCV def

A

gold standard measure of red cell mass, less affected by artefacts,

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12
Q

what to make sure of when PCV?

A

gentle mixing to avoid ‘decantification’ of cells

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13
Q

how do we measure PCV

A

(look at video on moodle)

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14
Q

microhaematocrit centrifuge

A

clay plug, red cells, buffy coat, white cells

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15
Q

how do we calculate pcv

A

PCV= A/B X100 where A is red cells and B is plasma + red cells

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16
Q

normal dog PCV

A

37-55%

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17
Q

normal cat PCV

A

26-45%

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18
Q

assessment of thickness of buffy coat

A

if > 1-2 mm then suggests increased white blood cell count –> inflammation or leukaemia

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19
Q

normal plasma colour

A

pale straw

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20
Q

red plasma

A

haemolysed sample –> free haemoglobin : in vitro or in the animal

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21
Q

yellow plasma

A

icterus

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22
Q

cloudy plasma

A

lipaemic –> endocrine disorders or…

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23
Q

how to get plasma protein concentration (PP)

Study These Flashcards
A

refractometer: degree of light refraction of the sample proportional to the total quantity of solids in the plasma

24
Q

false increase in PP

Study These Flashcards
A

lipaemia, increased urea (kidney failure), increased glucose (diabetes)

25
what if low PCV?
low plasma protein --> haemorrhage OR normal or hogh plasma protein --> haemolysis or reduced production of RBC
26
what if normal PCV
low plasma proteins --> low serum albumin OR high plasma protein --> high serum globulin (inflammatory response)
27
what if high PCV?
low or normal plasma protein --> polycythemia OR high plasma protein --> dehydration
28
caveat for analysing PCV and plasma protein
assume single pathological process: different things can affect these parameters independently
29
erythrogram
red cell count
30
leukogram
total white blood cell count
31
thrombogram
number and size of platelets
32
three main types of analysers
impedence analyser, flow cytometric analyser, quantitative buffy coat analyser
33
impedence analyser mechanism
cells passed through electric current --> cells passing trhough electric current causes pusle --> pulse height related to cell size and frequency related to cell number --> cells are then lysed --> white cell count measured after red cell lysis --> cell-specific lysing solutions added to allow differentiation of leukocytes: granulocytes, lymphocytes, monocytes
34
measured parameters of impedence analyser
RBC...
35
haematocrit calculation (RBC mass) HCT
RBCxMCV/1000
36
mean cell haemoglobin MCH
HGBX10/RBC
37
mean cell haemoglobin concentration
HGB/HCT
38
what if haematocrit is not within 2-3% of PCV
PROBLEM
39
what measure os gold standard?
PCV
40
potential errors of impedence analysers
* red blood cells and platelets differentiated based on size --> erros with large platelets * white blood cell count: falsely increased if nucleated red cells are present, should always check blood smear * three part leukocyte differential count often inaccurate, esp if morphological changes, should always check smear
41
flow cytometric based analyser mechanism
stream of cells through laser beam --> scatter --> low angle scatter correlates with cell size + high angle scatter correlates with cell granularity and internal complexity
42
advantage of flow cytometric analyser
better differentiates red cells and platelets, can differentiate between types of leukocytes, can identify and count reticulocytes
43
drawbacks of cytometric analyser
still prone to errors if morphological changes occur, often flags error
44
quantitative buffy coat analyser mechanism
blood drawn into microhaematocrit tube and centrifugal force used to separte red blood cells etc, tube contains fluorescent markers
45
problems with buffy coat analysers
rely on many assumtions so possible source of errors eg if cell sizes are abnormal
46
advantages of buffy coat analyser
calculate platecrit rather than platelet count --> better indication of platelet mass
47
blood smear examination use
validate results of automated CBC, identify morphological changes in the smear, band neutrophils classified as monocytes , morphological changes may be present before changes in cell numbers
48
important when making smear
to make it fresh otherwise cells in the tube start to degenerate whilst if do smear fresh and allow cells to air dry then the morphology will be preserved
49
blood smear preparation
use microhaematocrit tube --> place small drop of blood --> spreader slide in front of blood at an angle --> push spreader slide forward in one continuous motion to smear blood
50
blood smear examination
look at feathered edge at low power (10x lens) --> platelet clumps, large cells, microfilaria
51
what can you see in monolayer
50% of red cells touching each other,
52
what can you see at high power (100x): platelets
platelets, number of platelets in hpf, average of 5, normal<15 per hpf,
53
erythrocytes at high power
normal red cells, round in shape, colour --> polychromatophils, hypochromasia, lack central pallor, agglutination?, variation in size/shape, nucleated RBCs
54
leukocytes at high power
examine in 'zigzag' pattern, count 100 cells and number each type, compared with automated, check morphology and size
55
leukocytes
neutrophils (predominant), lymphocytes (sometimes predominant in cattle), monocytes, eosinophils, basophils

clinical pathology (3 decks)

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