Chap 13

Question 1

Platelet Satellitosis

Answer 1

When a PT’s blood is anticoagulated W/ EDTA, the PLTs surround or adhere to neutrophils.

Question 2

What can PLT satellitosis potentially cause (via auto methods)?

Answer 2

Pseudothrombocytopenia

Question 3

In PTs W/ pseudothrombocytopenia, what will the CBC report low?

Answer 3

PLTs, but its due to the clumping.

Question 4

Pseudoleukocytosis

Answer 4

spuriously low PLT counts W/ falsely increased WBC counts, can result from EDTA-induced PLT clumping. Happens when PLTs are similar in size to WBCs and auto-analyzer can not distinguish.

Question 5

What else can cause Pseudoleukocytosis?

Answer 5

PLT-Specific Autoantibodies

Question 6

What would be the best course of action to correct a PT’s EDTA-induced pseudothrombocytopenia or pseudoleukocytosis?

Answer 6

Redraw PT in a sodium citrate tube w/ proper ratio 9 parts blood to 1 part anticoagulant.

Question 7

Sources for blood film prep?

Answer 7

Blood in EDTA tube.
Blood in sodium citrate.
FInger or Heel sticks in heparinized micro-tubes.

Question 8

Techniques for making PB films?

Answer 8

Manual Wedge or push-type wedge

Question 9

Proper area for a PB smear Exam?

Answer 9

Red Cells slightly overlap.
Areas w/o WBCs are included.
Has a rainbow are where red cells touch (feathered edge).
Macroscopically, blood should appear pink to purple after staining.

Question 10

If RBCs appear gray, WBCs appear too dark, and Eos grans are gray, not orange, what may be the cause?

Answer 10

Stain or buffer too alkaline (Most Common).
Inadequate Rinsing
Prolonged Staining
Heparinized blood sample

Question 11

RBCs too pale or are red, WBCs are barely visible, what may be the cause?

Answer 11

Stain or buffer too acidic (Most common)
Underbuffering (Too short)
Over-rinsing

Question 12

Common problem when auto slide staining a slide w/ Leukemia?

Answer 12

Understaining

Question 13

Ideal microscopic appearance of a well-stained slide?

Answer 13

RBCs- appear orange to salmon pink.
WBCs- nuclei purple to blue.
Plasm of Neuts- pink to tan W/ violet or lilac grans.
Eos’- bright orange refractile grans.

Question 14

With a poorly stained or poorly prepared slide, what should your next step be?

Answer 14

Obtain a newly prepared and stained slide, if possible.

Question 15

WBC Estimate

Answer 15

1. Select an area of the blood film in which most RBCs are separated from one another with minimal overlapping of RBCs.
2. Using the 40× high-dry or 50× oil immersion objective, count the number of WBCs in 10 consecutive fields, and calculate the average number of WBCs per field.
3. To obtain the WBC estimate per microliter of blood, multiply the average number of WBCs per field by 2000* (if using the 40× high-dry objective) or 3000* (if using the 50× oil immersion objective).
4. Compare the instrument WBC count with the WBC estimate from the blood film.
   Example: If an average of three WBCs were observed per field:

Using a 40× high-dry objective, the WBC estimate is 6000/μL or mm3 or 6.0 × 109/L.

Using a 50× oil immersion objective, the WBC estimate is 9000/μL or mm3 or 9.0 × 109/L.

RBC, Red blood cell; WBC, white blood cell.

*WBC estimation factors of 2000 (40× objective) and 3000 (50× objective) are provided as general guidelines. A WBC estimation factor should be determined and validated for each microscope in use

Question 16

WBC and PLT Validation

Answer 16

Perform automated white blood cell (WBC) and platelet (PLT) counts on 30 consecutive fresh patient blood specimens. Make sure the results of quality control are “in control” for WBC and PLT.
2. Prepare and stain one peripheral blood film for each specimen.
3. Using the 40× high-dry or 50× oil immersion objective for the WBC estimate and the 100× oil immersion objective for the PLT estimate, select an area of the blood film in which most red blood cells (RBCs) are separated from one another with minimal overlapping of RBCs.
4. Count the number of WBCs or PLTs in 10 consecutive fields using the magnification specified in step 3, and calculate the average number of WBCs and PLTs per field.
5. For each of the 30 specimens, divide the automated WBC count by the average number of WBCs per field (40× or 50× objective); divide the automated PLT count by the average number of PLTs per field (100× objective).
6. Add the numbers obtained in step 5 for the WBCs, and divide by 30 (the number of observations in this analysis) to obtain the average ratio of the WBC count-to-WBCs per 40× or 50× field; add the numbers obtained in step 5 for the PLTs, and divide by 30 (the number of observations in this analysis) to obtain the average ratio of the PLT count–to–PLTs per 100× field.
7. Round the number calculated in step 6 to the nearest whole number to obtain an estimation factor for WBCs and PLTs at the specified magnification.

Question 17

PLT Estimate

Answer 17

Select an area of the blood film in which most red blood cells (RBCs) are separated from one another with minimal overlapping of RBCs.
2. Using the 100× oil immersion objective, count the number of platelets in 10 consecutive fields, and calculate the average number of platelets per field.
3. To obtain the platelet estimate per microliter of blood, multiply the average number of platelets per field by 20,000.*
4. Compare the instrument platelet count with the platelet estimate from the blood film.
Example: If an average of 20 platelets were observed per 100× oil immersion field, the platelet estimate is 400,000/μL or mm3 (400 × 109/L).

In instances of significant anemia or erythrocytosis, use the following formula for the platelet estimate:

Average number of platelets/field
×
total RBC count
200 RBCs/field

*A platelet estimation factor of 20,000 is provided as a general guideline. A platelet estimation factor should be determined and validated for each microscope in use

Question 18

What notation is best for reporting results of a PT’s CBC?

Answer 18

Scientific notation or conventional units
(SI= 2.6x10^3/uL) (CU= 2600/uL)

Question 19

Absolute WBC Differential Calculation

Answer 19

The # of WBCs counted x Auto WBC Count

Question 20

Absolute WBC Example
Calculate
63% Neutrophils W/ 8670 WBCs on the auto WBC Count?

Answer 20

0.63x8670= 5462 Neutrophils