Question

Questions: 1. What are some sources of error to the manual differential (other than misidentifying a cell)? 2. Describe how a platelet estimate is done:

Answer 1

1.What are some sources of error to the Manual Differential?

The sources of error to the manual differential may vary from person to person and also depending on the skills of the person who is performing the count .The errors are classified in to three types ,they are

• Natural errors(it maybe caused due to any changes in the environment )
• Instrument error (It maybe caused due to mishandling of the instruments )
• Human error (It maybe caused due to human inability)

Sources of Errors maybe

• Errors in dilution
• Counting errors
• Calculating errors
• Improper or inadequate shaking of the pipettes
• Failure to wipe out the excess blood from pipettes
• Failure to adjust the microscope during counting the cells
• Improper and inadequate cleaning of the pipettes and the glass wares involved in the count .
• Failure to allow cells to settle in single plane .
• Volume estimating error.
• Non differentiating between the cells and the debris .
• Improper monitoring of errors
• Mathematical calculating errors .

These are some sources of errors during a manual differential.

2.Describe how a platelet estimate is done ?

Platelet estimates are the important part in the evaluation of the peripheral blood smear .It helps to ensure the accuracy of the automated platelet count and provide a analysis of blood smear quantitative analysis .So it is very important to estimate the platelet count .

To calculate the platelet count the following procedure to be done .

• The platelet estimate is performed under 100x oil immersion objective lens .
• A rough estimate can be done if there are 7 to 25 platelets per oil immersion field, proving the count of platelet is adequate which states that there are 200RBC’s per oil immersion field .
• If patient is anemic  the following formula is used to calculate the platelet estimate .It is calculated as

Average number of platelets in one field x total number of RBC ‘s

Number of RBC’s in all fields .

The estimation of the platelet count is a routine laboratory test which should be done a daily basis for the patients who are admitted in the health care settings.