Blood film

The blood smear (English blood smear, blood film) is a method for the preparation of whole blood for microscopic examination. It is used for simple cytological or hematological assessment of the blood cells ( differential blood count ) and the detection of bacteria, filarial, plasmodia and other parasitic pathogens in peripheral blood.

If you give whole blood directly on a microscope slide, the density of red blood cells (erythrocytes) is usually so high that a differentiated assessment of white blood cells (leukocytes ) is not possible.

Technology

Using two slides. At first it brings at a distance of about 1 cm to one of the narrow edges of the drop of blood (see figure ). From the free side one approaches the edge of the second slide held at an angle this drop until he wins wide contact. Then it sweeps back in the other direction, so that the blood is thinned as a train without pressure. Thus, the blood cells are isolated and can be better assessed.

The smear is air dried, fixed, and can then be stained by the usual methods, such as the Giemsa stain or Pappenheim staining.

The normal blood smear is known in tropical medicine also known as " Slim Drops " to distinguish it from the so-called thick smear, in which a high density is desired to blood cells in the visual field of the microscope.

Staining techniques

• Pappenheim staining ( panoptic stain, May-Grunwald -Giemsa )
• Romanowsky staining
• Giemsa staining
• Wright stain
• Jenner staining
• Leishmania staining
• Field staining