Anemia is due to a decrease in blood volume, an inability to produce new red blood cells, or a genetic condition. When looking at red blood cells under a microscope, the technologist looks for hypochromia, which is a decrease in the amount of hemoglobin in each cell. The red blood cells, which normally have a small area of pallor in the center will have a larger area of central pallor. In very severe cases of anemia the cells may appear as a rim of red around a large area of white. Even in the presence of a large amount of cells, if there is severe hypochromia, this correlates with a decrease in hemoglobin and anemic conditions.
The technologist will also observe the appearance of the red blood cells. Generally the cells are round, however, under some conditions the shape may be altered. If the cells are fragmented, there is possibly a condition in the body that is tearing the cells. This could be due to DIC or disseminated intravascular coagulation. In this disease, there is fibrin that is being formed in the body which interferes with the movement of blood cells through the capillaries. Some of the cells become torn as they move through vessels and appear like "helmets" because of the manner in which the cells are usually torn.
There are genetic conditions that can be identified and viewed by looking at cells under a microscope. Cells with a sickle like appearance are long and may be slightly curved. Red blood cells that appear like a target, with a central area of color surrounded by a circle of white around it giving the cells the appearance of a target. These result from a hemoglobin disease that is genetically based, liver disease or splenectomy.