Heme Section13

Question 1

Manual Cell Counts
The grid is divided into 9 Primary (1) squares
Primary (1) square

Answer 1

1mm wide
x 1mm long
1mm2
x 0.1 mm deep with coverslip
0.1 mm3 Volume of a 1 square

Note: Typical WBC counting area is the 4 corner primary squares. For a low WBC, count a larger volume.

Question 2

Manual Cell Counts
Neubauer Hemocytometer

Answer 2

Entire ruled area
of one grid is:
3mm wide
x 3mm long
9mm2
x 0.1 mm deep with coverslip
0.9 mm3 Volume of entire grid

Question 3

Secondary (2) Square

Answer 3

0.2mm wide
x 0.2mm long
= 0.04mm2
x 0.1 mm deep with coverslip
= 0.004 mm3 Volume of a 20 square

Note: Typical  RBC counting area is 5 secondary squares.

Question 4

Manuel Platelet counts

Answer 4

Suggested squares used to count platelets are 10 secondary squares.

If the platelet count is very low you will need to count a larger volume (more squares).

Question 5

Tertiary (3) Square

Answer 5

0.05mm wide
x 0.05mm long
= 0.0025mm2
x 0.1 mm deep with coverslip
= 0.00025 mm3 Volume of a 30 square

Question 6

Manual Cell Counts Calculations
2 sides need to match within 10%

Answer 6

Average # cells counted x dilution factor
/volume counted

Average # cells counted
x dilution factor x depth (10)/
# of 1 squares counted

Question 7

Dilutions for Manual Cell Counts

Answer 7

WBC Leuko-tic 1:20

RBC 1:200

Plt Thrombo-tic 1:100

Question 8

Scientific Notation of Cell Counts

Answer 8

Express
WBC - one decimal place x 103 / mm3
-ex: 5,500 = 5.5 x 103 / mm3
12,300 = 12.3 x 103 / mm3
RBC - two decimal places x 106 / mm3
-ex: 4,230,000 = 4.23 x 106 / mm3
Eos - whole number / mm3
-ex: 542 / mm3
Plt - no decimals x 103 / mm3
-ex: 734,000 = 734 x 103 / mm3

Question 9

Manual Cell Counts For Eosinophil

Answer 9

For Eosinophil counts the entire grid is counted.

The two sides need to match within + 10% of each other.

To calculate the Eos count the 2 sides are totaled (instead of taking the average) and dividing by the corresponding number.