Blood Smear Preparation PDF
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This document provides a comprehensive guide on blood smear preparation. It covers the principles, requirements, procedure, and common causes of poor preparation. The document also includes a discussion of some biological factors affecting the quality of the blood smear.
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Blood Smear Preparation M LT P R A C T I C A L H E M AT O L O G Y LAB NO. …………….. 2 N D S TA G E Principle Smears are prepared by placing a drop of blood on a clean glass slide and spreading the drop using another...
Blood Smear Preparation M LT P R A C T I C A L H E M AT O L O G Y LAB NO. …………….. 2 N D S TA G E Principle Smears are prepared by placing a drop of blood on a clean glass slide and spreading the drop using another glass slide at an angle. The slide is then stained and observed microscopically. Requirements for Proper Smear Preparation: 1) Perfectly clean glass slides and (or) coverslips 2) Proper size blood drop. Procedure: 1. Place a 2-3 mm drop of mixed whole blood about 1 cm from the right side of frosted area of the slide. 2. Grasp a second slide (spreader slide) in the right hand between thumb and forefinger. 3. Place the spreader slide onto the lower slide in front of the blood drop, and pull the slide back until it touches the drop. 4. Allow the blood to spread by capillary action almost to the edges of the lower slide. Cont. 5. Push the spreader slide forward at approximately a 30- 40° angle, using a rapid, even motion. The weight of the spreader slide should be the only weight applied. Do NOT press down. Perform this step quickly. The drop of blood must be spread within seconds otherwise the cell distribution will be uneven. A thin film of blood in the shape of a bullet or tongue with a feathered edge will remain on the slide. 6. Label the frosted edge with patient name, ID# and date. 7. Allow the blood film to air-dry completely before staining. Procedure Note Characteristics of a Good Smear 1. Thick at one end, thinning out to a smooth rounded feather edge or as tongue form. 2. Should occupy 2/3 of the total slide area. 3. Should not touch any edge of the slide. 4. Should be margin free, except for point of application. Cont. As soon as the drop of blood is placed on the glass slide, the smear should be made without delay. Any delay results in an abnormal distribution of the white blood cells, with many of the large white cells accumulating at the thin edge of the smear. Rouleaux of the red blood cells and platelet clumping may also occur. Cont. The thickness of the spread when pulling the smear is determined by a. The angle of the spreader slide (the greater the angle, the thicker and shorter the smear). b. Size of the blood drop. c. Speed of spreading. Example 1. If the hematocrit is increased, the angle of the spreader slide should be decreased. 2. If the hematocrit is decreased, the angle of the spreader slide should be increased. Cont. Although this is the easiest and the most popular methods for producing a blood smear, it does not produce a quality smear, for example; the WBCs are unevenly distributed and RBC distortion is seen at the edges. Smaller WBCs such as lymphocytes tend to reside in the middle of the feathered edge. Large cells such as monocytes, immature cells and abnormal cells can be found in the outer limits of this area. Common causes of a poor blood smear: a. Drop of blood too large or too small. b. Spreader slide pushed across the slide in a jerky manner. c. Failure to keep the entire edge of the spreader slide against the slide while making the smear. d. Failure to keep the spreader slide at a 30° angle with the slide. e. Failure to push the spreader slide completely across the slide. f. Irregular spread with ridges and long tail: Edge of spreader dirty or chipped; dusty slide g. Holes in film: Slide contaminated with fat or grease h. Cellular degenerative changes: delay in fixing, inadequate fixing time or methanol contaminated with water. Biologic causes of a poor smear 1. a. Cold agglutinin - RBCs will clump together. Warm the blood at 37° C for 5 minutes, and then remake the smear. 2. b. Lipemia - holes will appear in the smear. There is nothing you can do to correct this. 3. c. Rouleaux - RBC’s will form into stacks resembling coins. There is nothing you can do to correct this.