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HEMA 1: LAB > Hemocytometer > Flashcards

Hemocytometer Flashcards

1
Q

Manual Cell Counting is used in the following circumstances:

A

Validity check of electronic methods for calibration purposes

Validity check of electronic counts in patients with profound leukopenia or thrombocytopenia

For blood specimens with platelet counting interferences

Back-up method

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2
Q

GENERAL PROCEDURES

A
  1. Specimen dilution
  2. Hemocytometer charging
  3. Microscopy (Viewing the ruled areas)
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3
Q

BLOOD DILUTION
Purpose

A

To avoid crowding of cells during manual counting

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4
Q

Name of pipette

A

Thoma pipette

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5
Q

Purpose of bead

A

For mixing

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6
Q

RBC Bulb units

A

100

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7
Q

WBC bulb unit

A

10

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8
Q

why the last calibration ends in 101 (for RBC) and 11 (for WBC)

One unit =_______

A

from the tip to the 1.0 mark

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9
Q

Size of the bulb

A

RBC - Larger
WBC -Smaller

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10
Q

Color of the bead

A

RBC - Red
WBC - White

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11
Q

Volume of the bulb

A

RBC - 100 units
WBC -10 units

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12
Q

Size of the bore

A

RBC - Smaller
WBC - Larger

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13
Q

Calibration

A

RBC - 0.5; 1; 101
WBC - 0.5; 1; 11

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14
Q

Dilution

A

RBC - 1:200
WBC - 1:20

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15
Q

Dilution factor

A

RBC - 200
WBC - 20

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16
Q

Diluting Fluids for WBC

A

2-3% Glacial Acetic Acid

1% Hydrochloric Acid

Turk’s Solution

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17
Q

The____ is the counting chamber used for manual counting of (3)

A

hemacytometer

white blood cells, red blood cells, and platelets.

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18
Q

The principle for counting all three cells are basically the same, only the (3) have differed.

A

dilution
diluting fluid
area for counting

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19
Q

Nowadays, the new improved_______ is the most commonly used hemacytometer for enumerating blood cells

A

Neubauer counting chamber

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20
Q

There are depressions, called “_____”,
“, that surround the platform.

A______ is positioned so that it covers both ruled areas of the hemocytometer.
This also allows the fluid in the chamber.

A

moats

coverglass

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21
Q

The two ruled areas of the hemocytometer have specific dimensions.

Each ruled area is consist of a large square (______). The total_____ area is divided into____ equal squares, each with____

A

3mm x 3 mm

9mm^2

nine

1mm^2

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22
Q

According to Rodak’s, all____ squares in the center are for platelet count).

A

25

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23
Q

-Depth of chamber =

A

0.1 mm

24
Q

Before using the hemocytometer,____ of the blood sample are first made.

A

dilutions

25
Q

T or F

Dilution for red cells, white cell, and platelet counts are done separately as each procedure uses different diluting fluids and equipment.

A

True

26
Q

T or F

The diluting fluids and pipettes used for each type of cell have different characteristics that allow the counting of one cell type of interest only

A

True

27
Q

RBC

Diluting Fluids

A

Hayem’s
Gower’s
Toisson’s
Bethel’s
Normal Saline Solution, 3.8%
Sodium Citrate
Formol Citrate

28
Q

Characteristics of the Diluting Fluid

A

RBC - Isotonic solution

WBC - Will hemolyze red blood cells except the nucleated RBCs;
Hypotonic solution

29
Q

Area counted

A

RBC - 0.2 mm2

WBC
(1:20) 4 mm2
(1:100) 9 mm2

30
Q

Objective

A

RBC - 40x HPO
WBC - 10x LPO

31
Q

Charging the hemocytometer
Clean the hemocytometer and coverslip with______.

Place the coverglass on the hemocytometer such that it covers______.

Charge the hemocytometer by touching the tip of the pipette to the point where the______ and ______ on one side meet.

Allow the fluid from the pipette to flow into one side of the hemocytometer by____ action.

The other side of the chamber is charged the same manner.

Before counting, the charged chamber should be allowed to stand for_____ in a moist chamber to allow settling of cells.

A

alcohol

both ruled areas

coverglass and the raised platform

capillary

10-15
minutes

32
Q

Viewing the ruled areas

Mount the charged hemocytometer on the microscope with________ in place.

Bring the stage closer to the objective using course adjustment until the etched lines come into view.

Use the fine adjustment knob for sharp focus of the etched lines.

A

low power objective (10x)

33
Q

The rule in counting
When counting, follow the _____pattern, where the______ and _____ are considered significant.

A

inverted L

upper and left boundaries

34
Q

Rule in counting

• For three-line boundary…

A

do not count the cells that touch only the outermost boundary

35
Q

Rule in counting

• If the cell touches both the mid and outermost boundary…

A

include it in the counting

36
Q

Rule in counting

• For two-line boundary, count the cells that…

A

touch up to the second boundary line

37
Q

Rule in counting

• For one-line boundary, count the cells that touch…

A

that single boundary line

38
Q

Rule in counting

• Whether the box has three-, two, or one-boundary line, do not count any cells that…

A

touch the right and lower boundary lines

39
Q

Rule in counting

• For the______ direction, start from the upper left corner box going to the right

A

serpentine

40
Q

Why must RBC solution be ISOTONIC?

A

Prevent lysis of RBC

41
Q

Why must WBC solution be ACIDIC or Hypotonic?

A

Will lyse ALL red blood cells except
nucleated RBCs

Enhances WBC nucleus

42
Q

Dilution =

A

volume of solute
total volume of solution

43
Q

RBC DILUTION
Computation for RBC Dilution
a. solute (pertains to the amount of blood sipped) -____ or _____

b. total volume of the solution (pertains to the volume capacity of the BULB) -_____

c. SOLVENT - just subtract_____ units from 100 units

A

0.5 units or 1.0 units

100 units

0.5

44
Q

cells/uL =

A

number of cells counted x dilution factor
—————
area counted x depth * (.1mm)

45
Q

Shortcut for solving

A

RBC = x1000
WBC = x50

46
Q

DETERMINING THE ALLOWABLE VARIATION IN THE COUNTS

Whether RBC, WBC, or platelets, both sides of the counting chamber should be counted.

The counts of the two sides need NOT be exactly the same.

There is an allowable variation.

The counts of the two sides of the hemocytometer should agree by______

A

10% or less less.

47
Q

To determine the allowable variation:

A
  1. Get the clifference of the two total counts
  2. Get the average of the two counts
  3. Divide the difference by the average and multiply by 100
48
Q

ALLOWABLE VARIATION IN THE COUNTS

the example, the answer is 5.97%. Therefore, the variation between the total counts of the two sides of the counting chamber is______.

A

acceptable

49
Q

When the outcomes in allowable variation is not acceptable,_________. In the case that the variation is still not acceptable after repeat charging, this warrants repeat______ or ______

A

repeat charging the hemocytometer

blood dilution or repeat blood collection.

50
Q

NOTE: If the average count obtained is in decimal (e.g. 112.5), always…

A

round up to whole number

51
Q

= 3.34 x 10^6uL

= 3.34 x 10^12/L

A

Conventional unit
S.I unit

52
Q

Why discard first 3 drops?

A

Conc. cells

53
Q

express with___ decimal points for RBC Count

express with___ decimal points for WBC Count

No decimal points for Platelet Count

A

2

1

54
Q

For a Standard leukocyte count within the reference range, there should be NO MORE THAN____-CELL DIFFERENCE between the highest and lowest total number of cells found among the eight 1-mm-corner squares (2 chambers) counted.

A

15

55
Q

For Standard erythrocyte count, there should be NO MORE THAN___-CELL DIFFERENCE between the highest and lowest total number of cells counted in the ten-0.04-mm^2 ( 2 chambers). Counts that do not meet these standards should not be reported. Rather, the procedure should be repeated.

A

20

HEMA 1: LAB (10 decks)

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