Thin Blood Film Report

PRACTICAL REPORT : PREPARATION OF THIN SMEAR AND WRIGHT STAIN
Title : Thin Blood Film preparation and Wright’s Stain for Parasitological Examination
Aim : To prepare thin blood film for Wright’s stain
Introduction :
To date, stained blood films are the most reliable and efficient means for definitive diagnosis of nearly all blood parasites. They provide a permanent record and can be sent to a reference laboratory for consultation or verification of diagnosis. Ordinarily, when a laboratory tests for blood parasites, two types of blood films are prepared: a thin film and a thick film. These can be made on the same microscope slide, that is, with the thin film on one end of the slide and the thick film on the other, or they can be made on separate

The thin film can be stained within a few minutes and will afford a quick diagnosis of malaria if the patient has a high degree of parasite; the thick film can be stained in a few hours and will afford a diagnosis of lighter infection; and the combination film is stained several hours later when the blood has dried longer, thus resulting in a better differential stain. The combination film is then used to verify the quick diagnosis and is kept as the permanent record. This three-slide procedure can be used for detecting all blood parasites.
Wright’s stain can be used to stain thin blood films for detecting blood parasites, but it is inferior to Giemsa for staining thick films. The staining reaction is somewhat similar to that of Giemsa and is achieved by using buffered water with a pH of 6.8. The stain contains the fixative and stain in one solution.
Principle

A properly made thin film is consists of an unbroken layer of red blood cells with the 'tongue' of the film not touching the edge of the slide. The thin film is dried immediately by waving the slide from side to side or by holding it for a few seconds in front of a fan which ensures a good preservation of the shape of the cells.
Staining :
1. Air-dried films are placed on a level staining rack.
2. A pipette is used to cover the surface of the slide with stain, adding stain drop by drop.
3. The number of drops needed is counted to cover the surface. It left at staining rack for 1 to 3 min which is the optimal staining time to obtain correct color range and intensity as it will vary with each batch of stain.
4. The same number of drops of buffered water is added to the slide as it was used of stain for step V.B.2 and the stain is mixed with water by blowing on the surface of the fluid.
5. After 4 to 8 min, the stain from the slide is flood with buffered water. As precaution, do not pour the stain off before flooding or a precipitate will be deposited on the slide.
6. The underside of the slide is wiped to remove excess stain.
7. It is left to air dry in a vertical position.

Results/Observation:
Smears will be evaluated on the following