Cell Count & Differential Count

Question 1

What is the primary cell count routinely performed on CSF specimens?

Answer 1

• LEUKOCYTE/WHITE BLOOD CELL COUNT.

Question 2

When are RBC counts typically determined in CSF specimens?

Answer 2

• Usually determined only when a TRAUMATIC TAP
• Has occurred and a correction for leukocytes or protein is desired.

Question 3

Why is it important to perform cell counts on CSF specimens ASAP (as soon as possible)?

Answer 3

• RBCs disintegrate within 1 hour
• WBCs decrease by 40% after 2 hours, which can affect the accuracy of the results.

Question 4

What is the significance of RBC disintegration within 1 hour in CSF specimens?

Answer 4

• This fact is significant because it emphasizes the need for timely analysis to obtain accurate cell count results.

Question 5

After how long does the WBC count decrease by 40% in CSF specimens?

Answer 5

• After 2 hours
• Highlighting the importance of prompt analysis to maintain the reliability of the results.

Question 6

What is pleocytosis in the context of cell count?

Answer 6

• Pleocytosis refers to an increase in the number of cells in the cerebrospinal fluid (CSF).

Question 7

What are the normal cell count values for adults, and which type of cells are predominant in adults?

Answer 7

• The normal cell count values for adults are 0-5 cells/uL
• And the predominant cells in adults are lymphocytes.

Question 8

What are the normal cell count values for neonates, and which type of cells are predominant in neonates?

Answer 8

• 0-30 cells/uL
• The predominant cells in neonates are monocytes, which are the largest white blood cells and precursor cells.

Question 9

What are two methods commonly used for cell counting?

Answer 9

• Manual counting using a Neubauer Counting Chamber
• And automated counting using Automated Cell Counters.

Question 10

What is the quality control requirement for cell counting?

Answer 10

• Should agree with automated cell counting results within a margin of ±25% as a quality control measure.

Question 11

How can you ensure the accuracy of cell counting results?

Answer 11

• It’s important to validate manual cell counts against automated counts
• Ensure they fall within the specified ±25% range for quality control.

Question 12

What does a significant RBC count in the Total Cell Count indicate?

Answer 12

• Suggests that a traumatic tap has occurred
• And is needed for the correction of WBC Count & CSF Protein Results.

Question 13

Why is the RBC count important in this context?

Answer 13

• It helps distinguish between a traumatic tap and other conditions
• And allows for accurate adjustments to WBC Count and CSF Protein Results.

Question 14

When can clear specimens be counted undiluted for Total Cell Count?

Answer 14

• Clear specimens may be counted undiluted for Total Cell Count.

Question 15

What is used as a diluent for Total Cell Count when needed, and what should be used for milky appearances in CSF?

Answer 15

• Normal Saline Solution (NSS) is used as a diluent, and it’s also used for milky appearances in CSF.

Question 16

What type of pipettes should be used for Total Cell Count, and why?

Answer 16

• Calibrated, automatic pipettes (MICROPIPETTE)
• Should be used for Total Cell Count to ensure accuracy and precision.

Question 17

How should cells be counted when performing Total Cell Count?

Answer 17

• Cells should be counted in the four corner squares and the center square of the specimen.

Question 18

Why is it necessary to lyse red blood cells (RBC) prior to counting white blood cells (WBC)?

Answer 18

• Lysing RBCs is necessary to ensure accurate WBC counts by eliminating interference from red blood cells.

Question 19

What is the diluent used for lysing RBCs in total cell count?

Answer 19

• A 3% glacial acetic acid solution is used as the diluent to lyse RBCs in total cell count.

Question 20

Is it possible to enhance the cell count process with Methylene Blue?

Answer 20

• Yes, Methylene Blue can be added to the diluting fluid to enhance the cell count process.

Question 21

What should be done if dilution is not required for cell counting?

Answer 21

• If dilution is not necessary
• The pipette should be rinsed with the diluting fluid prior to aspiration to maintain accuracy in the cell count.

Question 22

What is the standard calculation formula used for CSF cell counts?

Answer 22

• Used for CSF cell counts follows the same method as that used for blood cell counts.

Question 23

How many larger corner squares and larger center square are used for counting CSF cells?

Answer 23

• Four larger corner squares and the larger center square are used for counting CSF cells.

Question 24

What are the dimensions of the counting area for CSF cells?

Answer 24

• Has dimensions of 3mm length X 3mm width, divided into 9 large squares.

Question 25

How is the volume of CSF cells calculated?

Answer 25

* By multiplying the area of 1 square (1mm²) by the depth (0.1mm) * Which is the distance between the coverslip and the counter chamber. This gives a volume of 0.1mm³.

Question 26

What is the formula for calculating the volume of CSF cells?

Answer 26

* VOLUME = (Area in mm²) X (Depth in mm) = 0.1mm³.

Question 27

Why are calculations made to correct for WBCs in CSF due to a traumatic tap?

Answer 27

* Calculations are made to account for WBCs introduced in CSF during a traumatic tap to obtain an accurate WBC count.

Question 28

How is the Correct WBC Count calculated?

Answer 28

* Determined by subtracting the WBCs added during the traumatic tap from the actual WBC count in the cerebrospinal fluid.

Question 29

What does it indicate if peripheral WBC and RBC counts are normal?

Answer 29

* If peripheral white blood cell (WBC) and red blood cell (RBC) counts are within the normal range

Question 30

How can you correct for contamination in a cerebrospinal fluid (CSF) sample when white blood cells (WBC) have been added?

Answer 30

* Use the formula: WBC added = WBC Blood x RBC CSF / RBC Blood.

Question 31

What is the shortcut method for calculating the white blood cell count (WBC) in cerebrospinal fluid (CSF) based on the number of red blood cells (RBCs)?

Answer 31

* Subtract 1 WBC for every 700 RBCs present in the CSF * For example, if there are 1,400 RBCs/uL and 100 WBCs/uL, the calculated WBC count is 98 WBCs/uL.