Principles of Automated Hematology Quiz

When were the first counting chambers (hemacytometers) devised for viewing and counting cells using a microscope?

What method was used by W. H. Coulter's device to count blood cells?

Who patented a device that counted blood cells using the method of electrical impedance?

What did the researchers do to improve and standardize the hemacytometers?

What was added later to the hematology instruments after performing RBC and WBC counts?

What is the method used by the first hematology instruments to count blood cells?

What is the coefficient of variation (CV) for reliable instrument counts?

How are blood cells counted by electrical impedance?

Which technology was the only automated cell-counting method until the 1970s?

What was the problem with the first electrical-impedance cell counters?

How were accuracy and precision improved in electrical-impedance technology?

What information is typically displayed on a screen in a graph called a histogram?

What does electrical impedance measure when blood cells pass through an aperture?

What does light-scatter cell-counting technology measure?

How is electrical current conducted in electrical-impedance cell counting?

What does Coulter's principles form the basis for?

History of Hematology Instruments

First counting chambers (hemacytometers) were devised for viewing and counting cells using a microscope in the late 19th century.
W.H. Coulter's device counted blood cells using the method of electrical impedance.

Improvements in Hemacytometers

Researchers improved and standardized hemacytometers by adding a grid pattern, which helped to accurately count cells.
Later, platelet counting was added to hematology instruments after performing RBC and WBC counts.

Counting Methods

Early hematology instruments counted blood cells using the electrical impedance method.
Electrical impedance measures the changes in electrical current when blood cells pass through an aperture.
In electrical-impedance cell counting, blood cells interrupt the electrical current, which is then measured.

Instrument Accuracy and Precision

Reliable instrument counts have a coefficient of variation (CV) of <2%.
Accuracy and precision were improved in electrical-impedance technology by using more advanced electronics and improved aperture designs.

Limitations and Advances

The first electrical-impedance cell counters had a problem with clogging, which was later improved.
Until the 1970s, electrical impedance was the only automated cell-counting method.
Later, light-scatter cell-counting technology was developed, which measures the scatter of light by cells.
Coulter's principles form the basis for modern cell-counting instruments.

Data Analysis and Display

A histogram graph typically displays the distribution of cell sizes and counts.
Electrical impedance measures the changes in electrical current, which are proportional to cell size and volume.

Test your knowledge of the principles of automated hematology with this quiz. Explore the history of blood study, from William Harvey's observations to the development of counting chambers for cell analysis.