Basic Investigations in Haematology Lecture 3 - Total White Cell Count Flashcards

A set of flashcards on Total White Blood Cell Count (WBC) and differentials.

Significance of Total WBC Count and differentials includes __.

Monitor treatments (especially those that can cause leucopaenia), investigate unexplained fever, infections, monitor disease progression/severity or remission.

It is important to do __ when WBC counts are high.

A WBC differential count

Lysis of red blood cells in WBC count is produced by an __.

Acid solution

The total white cell count includes any __ which may be present.

Nucleated red cells

The true white cell count is obtained after __.

Blood film examination

A correction of WBC count is done if the amount of nucleated red blood cells is __.

≥10%

In principle of WBC test, WBCs are diluted in __.

An acid reagent

In the principle of WBC test, non-nucleated blood cells are __.

Haemolyzed

The cells are counted microscopically using __.

Improved Neubauer ruled counting chamber (haemocytometer)

WBC diluting fluid is also known as __.

Turk’s fluid

Turk’s fluid is a weak acid solution that contains __.

Glacial acetic acid solution

__ is added to Turk’s fluid to stain the nucleus of white cells.

Gentian violet

Glacial acetic acid is __.

A corrosive chemical with an irritating vapour

Handle glacial acetic acid in __.

Well ventilated room

__ venous or capillary blood is required for the WBC test.

EDTA anticoagulated

__ anticoagulated blood must not be used for WBC test.

Heparin or sodium citrate

The WBC count should be performed __ (blood should not be refrigerated).

Within 6 hours

The counting chamber recommended for cell counts is __.

Metalized surface (‘Bright-line’) double cell Improved Neubauer ruled chamber

__ are less expensive but not recommended.

Non-metalized haemocytometers

The chamber grid has an area of __.

9 mm2

The depth of the chamber is __.

0.1 mm

Other equipment required for WBC count includes tally counter, pipettes/calibrated capillary tubes and __.

Counting chamber cover glass

Measure __ of diluting fluid and dispense it into a small tube.

0.38 ml

Add __ of well-mixed EDTA anticoagulated venous blood to the diluting fluid.

0.02 ml

Press down on each side of the cover glass until __ are seen.

Rainbow colours (Newton’s rings)

Using a capillary tube, pipette, or bulb pipette held at an angle of about __, fill one of the grids of the chamber with the sample.

450

Leave the chamber undisturbed for __ to allow time for the white cells to settle.

2 minutes

Using the __ objective with the condenser iris closed sufficiently to give good contrast, focus the rulings of the chamber and white cells.

10x

Count the cells in the __ of the chamber.

Four large corner squares

After performing the count, before the sample dries, dismantle the chamber, __.

Wash and dry it

Absolute WBC count of each cell is given by __.

Percentage Diff count :X TWBC / 100

NORMAL WBC VALUES for ADULTS(CAUCASIANS) is __.

4.0 – 10.0 x 109/L

NORMAL WBC VALUES for AFRICANS is __.

2.6 – 8.3 x 109L

NORMAL WBC VALUES for PREGNANT WOMEN is __.

Up to 15 x 109/L

D in the formula of calculation stands for __.

Diluting factor

Whenever possible perform WBC counts in __.

Duplicate

The difference between the two counts (as a percentage of the mean) should not be more than __.

20%

When the difference between the two counts (as a percentage of the mean) is more than 20%, __.

Repeat the counts

For low WBC counts, after performing the calculation you have to __.

Divide the results by 2

For high WBC counts, after performing the calculation you have to __.

Multiply the results by 2

When more than 10 nucleated red blood cells (RBCs) per 100 WBC are present in the blood film, __.

Correct the WBC count

Incorrect measurement of blood is due to __.

Poor technique or using a wet or chipped pipette

Source of error when using anticoagulated blood is __.

Not mixing the blood sufficiently or not checking the sample for clots

A source of error in manual WBC counts is __.

Not checking whether the chamber and cover glass are completely clean

A source of error in manual WBC counts is __.

Over-filling a counting chamber or counting cells when the sample contains air-bubbles

A source of error in manual WBC counts is __.

Not allowing enough time (2 minutes) for the cells to settle in the chamber

A source of error in manual WBC counts is __.

Using too intense a light source or not reducing the iris diaphragm sufficiently to give good contrast

A source of error in manual WBC counts is __.

Not completing counting of the cells before the sample begins to dry in the chamber

A source of error in manual WBC counts is __.

Not correcting a count when the sample contains many nucleated RBCs

Significance of test is to __.

Monitor treatments

Significance of test is to __.

Investigate unexplained fever

Significance of test is to __.

Investigate infections

Significance of test is to __.

Monitor disease progression/severity

Significance of test is to __.

Monitor remission

Blood is diluted with a fluid that __.

Lyses the red cells

Blood is diluted with a fluid that does not lyse the __.

Nucleated red cells

WBC diluting fluid contains __.

Glacial acetic acid

Gentian violet stains the __.

Nucleus of white cells

Glacial acetic acid is a __ chemical.

Corrosive

Glacial acetic acid has __.

Irritating vapour

Use __ anticoagulated blood.

EDTA

Use a __ counting chamber.

Bright-line

__ haemocytometers are not recommended.

Non- metallized

Use a __ during equipment.

Tally counter

Measure __ of diluting fluid.

0.38 ml

Add __ of blood.

0.02 ml

Make sure the central grid areas are __.

Clean and dry

Press down until __ are seen.

Newton’s rings

Allow time for the white cells to be __.

Settled

Use the __ when focusing the cells.

10x objective

Focus the cells until they appear as __.

Black dots

Count the cells in the __.

Four large corner squares

__ are also counted in blood film.

Nucleated RBcs/Normoblasts

Incorrect measurement of blood due to __.

Poor technique

Check the sample for __.

Clots

Avoid using a __ pipette.

Wet

Avoid counting cells with __.

Air bubbles

__ increases with the number of cells counted.

Precision

When the difference is more than 20%, it is termed __.

Coefficient of variation