Blood smear
.jpg)
The blood smear (Engl. Blood smear , blood movie ) is a method for the preparation of whole blood for microscopic examination. It is used for simple cytological or hematological assessment of blood cells ( differential blood count ) as well as the detection of bacteria , filariae , plasmodia and other parasitic pathogens in the peripheral blood.
If whole blood is placed directly on a slide , the density of the red blood cells ( erythrocytes ) is usually so high that a differentiated assessment of the white blood cells ( leukocytes ) is not possible.
technology
Two slides are used. First, apply the drop of blood at a distance of about 1 cm from one of the narrow edges (see fig.). This drop is approached from the free side with the edge of the second inclined slide until it makes broad contact. Then you stroke back in the other direction so that the blood is thinned out like a train without pressure. As a result, the blood cells are scattered and can be better assessed.
The smear is air-dried, fixed and can then be stained with the usual methods , for example Giemsa staining or Pappenheim staining .
The normal blood smear is also referred to as "thin drop" in tropical medicine to distinguish it from the so-called thick drop , in which a high density of blood cells is desired in the microscope's field of view.
Dyeing techniques
- Pappenheim staining (panoptic staining, May-Grünwald-Giemsa)
- Romanowsky staining
- Giemsa stain
- Wright stain
- Jenner staining
- Leishmania staining
- Field staining
