The History of Complete Blood Count Test: From Microscope to Machine

Complete blood count (CBC) test is one of the most common and important blood tests that measures the number and characteristics of different types of cells in the blood, such as red blood cells, white blood cells, and platelets. CBC test can help diagnose and monitor various diseases and conditions, such as anemia, infection, inflammation, bleeding, and cancer. But how did this test come to be? In this text, we will explore the history of CBC test from its origins in the 19th century to its modern developments in the 21st century.

The Origins of CBC Test: The Microscope Era

The history of CBC test begins with the invention of the microscope in the 17th century, which opened a new window to the microscopic world of living organisms. The first person to observe and describe blood cells under a microscope was Antonie van Leeuwenhoek, a Dutch scientist and inventor, who reported his findings in a letter to the Royal Society of London in 1674. He described red blood cells as “little globules” and white blood cells as “very small animalcules”. However, he did not measure or count them.

History of complete blood count test

The first attempt to measure and count blood cells was made by Karl Vierordt, a German physiologist, who invented a device called a hemocytometer in 1852. A hemocytometer is a glass slide with a grid etched on it, which allows counting the number of cells in a known volume of blood. Vierordt used his device to measure the number of red blood cells and white blood cells in healthy and diseased people. He also introduced the concept of hematocrit, which is the ratio of red blood cell volume to total blood volume.

The next milestone in the history of CBC test was the development of staining techniques, which allowed distinguishing different types of blood cells based on their color and shape. The most influential staining technique was the Romanowsky stain, which was invented by Dmitri Romanowsky, a Russian physician, in 1891. The Romanowsky stain consists of a mixture of methylene blue and eosin, which colors different types of white blood cells differently. For example, neutrophils are stained pink, eosinophils are stained red, basophils are stained blue, lymphocytes are stained purple, and monocytes are stained gray. The Romanowsky stain also colors red blood cells red and platelets purple.

Using the microscope, the hemocytometer, and the staining techniques, scientists and doctors were able to perform manual CBC tests by counting and classifying different types of blood cells under a microscope. However, this method was time-consuming, labor-intensive, and prone to errors. Therefore, there was a need for more automated and accurate methods of CBC testing.

The Evolution of CBC Test: The Machine Era

The history of CBC test entered a new era with the invention of machines that could measure and count blood cells automatically. The first machine that could measure hematocrit was invented by Otto Zillessen, a German engineer, in 1906. His machine used centrifugal force to separate red blood cells from plasma and then measured their volume using a photometer. Later versions of his machine could also measure hemoglobin concentration using a colorimeter.

The first machine that could count blood cells was invented by Wallace Coulter, an American engineer, in 1953. His machine used the principle of electrical impedance, which means that the resistance of a fluid changes when a particle passes through a small aperture. By measuring the change in resistance, the machine could count and size the particles. Coulter applied his machine to count red blood cells and white blood cells in blood samples. He also developed a method to differentiate white blood cells based on their size and shape using a histogram. His machine was called the Coulter counter and became widely used in clinical laboratories.

The next generation of machines that could count blood cells was based on the principle of flow cytometry, which means that the cells are illuminated by a laser and their optical properties are measured by detectors. By using different wavelengths of light and different types of detectors, the machines could measure various parameters of blood cells, such as hemoglobin concentration, cell volume, cell shape, cell surface markers, and cell internal structures. The first machine that used flow cytometry to count blood cells was invented by Louis Kamentsky, an American biophysicist, in 1965. His machine was called the Cytofluorograph and could measure fluorescence and light scattering of cells stained with fluorescent dyes.

The modern machines that can perform CBC test are based on the combination of electrical impedance, flow cytometry, and other technologies, such as optical microscopy, digital imaging, and artificial intelligence. These machines can measure and count different types of blood cells with high accuracy and speed, as well as provide additional information about their morphology and function. Some examples of these machines are Sysmex XN-Series, Abbott Alinity hq, and Beckman Coulter DxH 900.

pathologist analyse blood cells

But now there are digital microscopes that combine the advantages of traditional microscopy and automated systems.

How Celly digital microscope works

Celly CBC test works by combining the technologies of digital microscopy, image analysis, artificial intelligence, and cloud computing. The process of Celly CBC test consists of the following steps:

  • Sample preparation. A blood sample is collected from a patient and stained with a special dye that colors different types of blood cells differently. The stained blood sample is then placed on a glass slide and inserted into a Celly analyzer.
  • Image acquisition. The Celly analyzer uses an iPhone camera to capture high-resolution images of the blood cells on the slide. The images are then transferred to a computer or a cloud server for further processing.
  • Image analysis. The computer or the cloud server uses artificial intelligence algorithms to analyze the images and identify, classify, and count different types of blood cells. The algorithms use various features of the blood cells, such as size, shape, color, and internal structures, to distinguish them from each other. The algorithms also detect any abnormal or immature cells that may indicate a disease or a condition.
  • Result presentation. The results of the image analysis are presented in a graphical and numerical format on a screen or a report. The results include the total number and percentage of each type of blood cell, as well as other cell parameters. The results also show any abnormal or immature cells that were detected by the algorithms.
  • Result validation. The results of the image analysis are validated by a human operator, who can review the images and the results on a screen or a report. The operator can confirm, modify, or reject the results based on their expertise and judgment. The operator can also add comments or annotations to the results.

Benefits of Celly CBC Test

Celly CBC test has several benefits over traditional manual or automated methods of CBC testing, such as:

  • Accuracy and consistency. Celly CBC test uses artificial intelligence algorithms that are trained on large databases of blood cell images from different sources and conditions. These algorithms can recognize and classify different types of blood cells with high accuracy and consistency, regardless of the variations in staining quality, slide preparation, image quality, or operator skill.
  • Speed and efficiency. Celly CBC test can process hundreds of blood tests per day, which is much faster than manual microscopy. This reduces the turnaround time and improves the workflow of the laboratory.
  • Ease and convenience. Celly CBC test does not require any special skills or training to operate. The operator only needs to insert the slide into the analyzer and review the results on a screen or a report. The operator can also access the results remotely via cloud computing or mobile devices.
  • Quality and safety. Celly CBC test reduces the exposure to biohazardous materials and human errors that may occur during manual or automated methods of CBC testing. The analyzer also has built-in quality control features that monitor the performance and calibration of the system.


CBC test is a vital blood test that has a long history of development and innovation. From the microscope era to the machine era, CBC test has evolved from a manual and tedious method to an automated and sophisticated one. CBC test can provide valuable information about the health status and disease conditions of patients, as well as contribute to the advancement of medical science and technology.