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Hematology > Automated Test Methods > Flashcards

Automated Test Methods Flashcards

1
Q

What is the impedance principle

A

based on the detection and measurement of changes in electrical resistance produced by cells passing through a small aperture

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2
Q

How is cell count determined using impedance

A

the number of voltage pulses

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3
Q

How is cell size determined using impedance

A

the length or height of voltage pulses

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4
Q

What method does the Beckman analyzer use

A

gentle vaccum

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5
Q

What method does the Sysmex analyzer use

A

hydrodynamic focusing

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6
Q

What is a total vote out

A

if 2 or 3 repeat counts are mismatched no results are reported

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7
Q

What is a partial vote out

A

if one repeat count is mismatched, the instrument will flag but results will be reported

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8
Q

What are characteristics of RBC histograms

A

cells between 36 and 360fL
one main population with a guassian distribution
curve should begin at baseline
smaller population to the right of the main population are cells that have been corrected for coincidence

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9
Q

What are atypical findings in a RBC histogram

A

more than one cell population
wide distribution
high take off due to interferences of particles approx 36fL

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10
Q

What are characteristics of PLT histograms

A

cells counted between 2-20fL
curve of best fit is overlaid on raw data
curves start and stop at baseline

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11
Q

What are atypical findings in PLT histograms

A

curve stops above baseline
fitted curve cannot be drawn
fitted curve does not fit raw data
high take off

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12
Q

What are characteristics of WBC histograms

A

cells counted larger than 35fL
should start or be really close to the baseline
typically 3 distinct populations

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13
Q

What are atypical findings in WBC histograms

A

high take off due to interferences

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14
Q

How is hemoglobin measured

A

spectrophotometry

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15
Q

What does forward scatter determine

A

size/shape of cell

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16
Q

What does side scatter determine

A

complexity and granularity of cells

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17
Q

What does fluorescence determine

A

nucleic acids present in the cell

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18
Q

What is the principle of flow cytometry

A

cells are focused via hydrodynamically focused sheath of fluid and inserted into the light path one at a time they are hit by a laser and the scatter and passage of light is gathered by photodetection

19
Q

What parameters are measured in the RBC/PLT bath

A

RBC and PLT count

20
Q

What parameters are measured in the WBC bath

A

WBC count

21
Q

What happens in the hemoglobinometer of a beckman instrument

A

lysing reagent contains a cyanide pigment that binds and stabilizes the free hemoglobin the absorbance is measured at 525nm and concentration is calculated using Beers law

22
Q

Beckman instruments use VCS what is this

A

volume analysis
conductivity analysis
light scatter analysis

23
Q

What are the components of the 5 part differential a Beckman instrument does

A

neutrophils, lymphocytes, monocytes, basophils and eosinophils

24
Q

How is HCT determined

A

(RBCxMCV)/1000

25
Q

How is MCHC determined

A

HGB/HCT

26
Q

How is MCH determined

A

HGB/RBC

27
Q

What are the components of the 6 part differential a sysmex instrument does

A

neutrophils, monocytes, lymphocytes, basophils, eosinophils and immature granulocytes

28
Q

What happens in the hemoglobinometer of a sysmex instrument

A

hemoglobin is oxidized and SLS is added to form SLS-HGB complex which is measured spectrophotometrically at 555nm

29
Q

What can cause falsely increased WBC counts

A

NRBCs, Megakaryocyte fragments, micro megakaryocytes, PLT clumps, giant PLT, RBCs resistant to lysis, microorganisms, fibrin strands

30
Q

What can cause falsely decreased WBC counts

A

WBC fragmentation, WBC clumps, very small lymphocytes

31
Q

What can cause falsely increased RBC counts

A

very high WBC count, giant PLT, fibrin strands

32
Q

What can cause falsely decreased RBC counts

A

cold agglutinins, microcytes, schistocytes, hemolysis

33
Q

What can cause falsely increased PLT counts

A

small RBC/WBC, schistocytes, microorganisms, WBC fragments, electronic noise

34
Q

What can cause falsely decreased PLT counts

A

PLT clumps, old specimens, giant PLT, PLT satellitism

35
Q

What can cause falsely increased HGB

A

lipemia, icterus, hemolysis, high WBC count

36
Q

What can cause falsely decreased HGB

A

cells that resist lysis

37
Q

What can cause falsely increased HCT

A

high WBC count, giant PLT, fibrin strands

38
Q

What causes falsely decreased HCT

A

cold agglutinins, microcytes, schistocytes, hemolysis, excess EDTA

39
Q

What causes falsely increased MCV

A

hyperglycemia and hypernatremia, cold agglutinins, old specimen

40
Q

What causes falsely decreased MCV

A

excess EDTA

41
Q

What causes falsely increased MCHC

A

lipemia, icterus, cold agglutinin, hemolysis, high WBC count

42
Q

What is coincidence

A

when more than one cell passes through the aperture at the same time. This can falsely decrease cell counts and falsely increase cell volumes

43
Q

What does protein build up at the aperture cause

A

increased resistance which results in falsely low cell counts and falsely elevated cell volumes

Hematology (7 decks)

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