How is a blood-type test conducted?

A blood-type test is conducted by mixing blood with specific antibodies that react with particular antigens present on the surface of the red blood cells. This process can lead to agglutination, which is the clumping of cells, indicating the presence or absence of certain blood type markers (A, B, AB, or O). This reaction provides the necessary information to determine an individual's blood type.

The approach focuses on how the blood cells react to the introduced antibodies, making it a direct and efficient method for identifying blood types used in transfusions and forensic investigations. Furthermore, this method is based on known immunological responses, ensuring accuracy in results.

Other approaches, such as analyzing the size of blood cells or observing blood under a microscope, lack the specificity required for blood typing. Measuring blood viscosity pertains to the thickness of the blood and does not provide information about the antigen-antibody interactions that define blood types.