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MLSCI330 Hematology > Automated Testing > Flashcards

Automated Testing Flashcards

1
Q

Principle of electronic impedance in cell counting. What is it based on?

A
  • cells suspended in conductive liquid (Isotonic diluent) that acts as electrical insulators
  • flow of current is established between two submerged electrodes
  • cells pass through an aperture by gentle vacuum/hydrodynamic focusing* = pulses and resistance to electrical flow can be counted and sized as a particle

*NOTE: Beckman vs Sysmex

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2
Q

Purpose of diluent in cell counting baths

A
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3
Q

“Number of voltage pulses” represents which hematologic parameter ?

A

Cell count

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4
Q

“Height of voltage pulses” represents which hematologic parameter ?

A

Cell volume

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5
Q

Define “co-incidence” in hematology

A
  • 2 or more cells pass the aperture at the same time = 1 pulse counted as 1 cell
  • cell count is falsely decreased and pulse height is falsely increased
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6
Q

How are histograms created ?

A
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7
Q

What is “aperture voting ?”

A
  • Values counted in triplicate must match
  • If 2/3 match = partial vote out
  • If 2 or all 3 values do not match = total vote out
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8
Q

How is Hb value determined on Beckman Coulter ?

A
  • lysing agent added to WBC dilution = lyses RBCs + release Hgb
  • AFTER WBC COUNT, sample is taken to the SPECTROPHOTEMETER where Hgb is measured at 525nm
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9
Q

How is optical scatter used to study cells ?

A

Forward light scatter: cell size
Side scatter: cell complexity/ granularity

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10
Q

VCS in Beckman Coulter analyzers

A
  • differentiate WBCs

Volume:
Conductive:
Light Scatter:

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11
Q

Which WBCs are included in the 6-part differential on the Sysmex ?

A
  1. neutrophils
  2. lymphocytes
  3. monocytes
  4. eosinophils
  5. basophils
  6. myeloids
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12
Q

How do Sysmex analyzers differentiate WBCs ?

A
  • fluorescent flow cytometry differentiates WBCs
  • fluorescence = RNA/DNA content
  • forward scatter = cell size
  • side scatter = granularity/cell complexity
  • polymethine dye is used to stain WBCs
  • 6-part differential includes: neutrophils, lymphocytes, monocytes, eosinophils, basophils, and immature granulocytes /myeloids
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13
Q

Significance of increased retic count

A

Anemia due to red blood cells being destroyed earlier than normal (hemolytic anemia)

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14
Q

3 general causes of increased retic count

A
  1. Hemolytic anemia
  2. Blood loss
    3.
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15
Q

How do Beckman Coulter determine retic count ? What parameters are used and how are they measured ?

A
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16
Q

How do Sysmex analyzers determine retic count ? What parameters are used and how are they measured ?

A
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17
Q

When would a manual retic count be indicated instead of an automated count ?

A
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18
Q

What stain is used for manual retic counts ? What does this stain do to retics ?

A

New methylene blue; causes clumping and staining of residual nucleic acid present in immature cells.

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19
Q

Minimum requirement for a stained red cell to be a retic

A
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20
Q

Manual staining procedure for retics (dilution, incubation time, etc.)

A
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21
Q

Manual counting procedure for retics (relative and absolute counts)

A
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22
Q

What are the allowable ranges (technical accuracy limits) when comparing retic counts on two slides ?

A

0 - 2%=
2.1 - 5%=
>5% =

23
Q

Ref: relative retic count (>1 week old)

A
24
Q

Ref: absolute retic count (>6 months old)

A
25
Q

MCV (fL)

A

HCT/RBC x 1000

26
Q

MCHC (g/L)

A

HGB/ HCT

27
Q

MCH

A

HGB/ RBC

28
Q

WBC estimate when 35 WBC /3 lpf and WBC field factor = 4

A

2.9 x10^9/L

29
Q

PLT estimate when 260 PLT /10 hpf and PLT field factor = 14

A

364 x10^9/L

30
Q

What is measured using electrical impedance in the 2-20fL range ?

A

PLT count

31
Q

What is calculated directly from the RBC histogram ?

A

RDW

32
Q

What is determined by the cumulative pulse height of RBC on Sysmex analyzers ?

A

HCT

33
Q

What is measured only by electrical impedence in either Sysmex or Beckman-Coulter analyzers ?

A

RBC count

34
Q

What is calculated using hemoglobin and RBC count on Beckman-Coulter analyzers ?

A

MCH

35
Q

What is calculated using hematocrit and RBC count on Sysmex analyzers ?

A

MCV

36
Q

What is measured by forward light scatter and side fluorescent light detection on Sysmex analyzers ?

A

WBC count

37
Q

Crit: Hgb

A

Adult: <70 g/L
<8 days: <70 g/L
All: >239 g/L

38
Q

Crit: WBC count

A

<0.6 x10^9/L
>99.9 x10^9/L

39
Q

Crit: PLT count

A

Inpt: <10 x10^9/L
Outpt: <20 x10^9/L

40
Q

MCV formula (L/L)

A

HCT/ RBC x 1000 =

41
Q

MCH formula

A

HGB/ RBC

42
Q

MCHC formula (g/L)

A

HGB/ HCT

43
Q

Which of the following is true regarding automated reticulocyte counts?

a.
Reticulocytes will have decreased electrical impedance compared to mature RBC

b.
Reticulocytes will have decreased forward scatter compared to mature RBC

c.
Reticulocyte RNA content determines optical light scatter

d.
Reticulocyte fluorescence increases with maturity on Sysmex analyzers

A

c.
Reticulocyte RNA content determines optical light scatter

44
Q

Which of the following statements about RBC counts on a Beckman analyzer is(are) true? Select all that apply:

a.
RBCs are counted if they are >35fL

b.
RBCs are counted in the same bath as PLT

c.
A lysing agent is added to dilute the sample prior to counting

d.
RBCs are counted as they impede the flow of a current

A

a.
RBCs are counted if they are >35fL

b.
RBCs are counted in the same bath as PLT

d.
RBCs are counted as they impede the flow of a current

45
Q

Which of the following parameters will be affected by lipemia in the sample? Select all that apply:

a.
RBC count

b.
MCH

c.
MCHC

d.
Hemoglobin

A

b.
MCH

c.
MCHC

d.
Hemoglobin

NOTE: RBC count is determined by electrical impedance, not spectrophotometry

46
Q

Which of the following interferences are eliminated by performing a fluorescent platelet count (PLT-F) on Sysmex analyzers? Select all that apply:

a.
PLT clumps

b.
Schistocytes

c.
Very small RBCs

d.
Giant PLT

A

b.
Schistocytes

c.
Very small RBCs

d.
Giant PLT

47
Q

How is the WBC count determined on Beckman Coulter analyzers?

A

Electrical Impedance

48
Q

A patient’s WBC count on a Beckman analyzer is 480.4 x 109/L. Which of the following parameters will be unaffected?

a.
MCHC

b.
PLT count

c.
RBC count

d.
Hemoglobin

A

b.
PLT count

49
Q

How is the platelet count determined on Beckman analyzers?

A

Electrical impedance

50
Q

How can precision checks be performed on hematology analyzers?

a.
A normal patient is analyzed 6 times and the SD is calculated

b.
A normal patient is analyzed 6 times and the CV is calculated

c.
A commercial whole blood control is analyzed 6 times and the SD is calculated

d.
A commercial whole blood control is analyzed 6 times and the CV is calculated

A

b.
A normal patient is analyzed 6 times and the CV is calculated

51
Q

Formula for corrected WBC

A

(absolute WBC x 100) / (nRBC + 100)

52
Q

T or F: The Giemsa stain is a nuclear stain and demonstrates inclusions well

A

TRUE; the Giemsa stain is a nuclear stain and demonstrates inclusions well

53
Q

Select reportable:
- 3-6 shistocytes /100 RBC
- PLT est = 85 x 109/L
- 1-2 hypochromic cells/100 RBC
- 1-2 tear cells/100 RBC
- 1 Howell-Jolly

A

3-5% shisctocytes

54
Q

A patient has been admitted to the ED after a car accident. They were bleeding profusely and transfusion testing is currently underway to cross-match 2 units of packed cells.

CBC results showed:
Hgb = 69 g/L
PLT = 89 x 10^9/L

PBS:
3-6 shistocytes /100 RBC
PLT est = 85 x 109/L
1-2 hypochromic cells/100 RBC
1-2 tear cells/100 RBC
1 Howell-Jolly

Is there any other follow-up required for this patient?

A
  • critical Hgb called to the ward
  • pathologist notified of schisto + low PLT and smear left to be reviewed

MLSCI330 Hematology (10 decks)

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