The blood elements (including parasites, if any) are more concentrated (app. 30×) than in an equal area of a thin smear. Thus, thick smears allow a more efficient detection of parasites (increased sensitivity). However, they do not permit an optimal review of parasite morphology.
What is the disadvantage of preparing thick smears for bacterial smears?
Do NOT make your smear suspensions too thick. The dye will not penetrate well, and there will be far too many bacterial cells to see individual shapes and arrangements.
Why must a smear be made thin?
Why is it important to make the smear thin? thin smear, because the thickness will determine whether or not you can visualize individual cell morphology(form), their arrangements, or details regarding gram reaction or internal structure. … so that you can view individual cells by themselves rather than in a cluster.
What is the disadvantage of a thick smear over a thin smear when staining?
the disadvantages of: 1. thick blood film cannot identify the e.g. Plasmodium species because of dehemoglobinized of RBCs in thick smear. … thin blood film it depend of the thickness of thin smear of the blood film the quality of the smear it depend on the morphology and size of erythrocytes.What is the purpose of thick blood smear?
A thick blood smear is a drop of blood on a glass slide. Thick blood smears are most useful for detecting the presence of parasites, because they examine a larger sample of blood. (Often there are few parasites in the blood at the time the test is done.)
What are the errors to avoid when making a blood smear?
What are five errors to avoid when making a blood smear? Do not use dirty slides; do not use too large a drop of blood; do not delay in spreading the blood; do not apply too much pressure to the spreader slide; and do not dry the smears in a humid environment which will prolong the drying time.
What are the factors that affect the thickness and thickness of a blood smear?
The perfect quality smear is influ- enced by three factors: speed, angle and drop size. thinner the smear will be. The slower the slide is moved, the shorter and thicker the slide will be.
What if the smear you prepare becomes too dense?
2. What if the smear you prepare becomes too dense? When the smear becomes too dense it becomes harder for light to pass through which makes it har to see the shape and size of the organism. … Gram variability is when the organism you are staining is a mix of red (gram negative) and purple (gram positive).What are the advantages and disadvantages of using thick blood film in malaria parasites?
Thick blood film More sensitive by 30 times than thin films because: the blood is concentrated allowing a greater volume of blood to be examined and. malaria parasites are concentrated as the RBCs are lysed.
How does Giemsa stain work?Giemsa solution is composed of eosin and methylene blue (azure). The eosin component stains the parasite nucleus red, while the methylene blue component stains the cytoplasm blue. The thin film is fixed with methanol. De-haemoglobinization of the thick film and staining take place at the same time.
Article first time published onHow do you use Giemsa stain?
- On a clean dry microscopic glass slide, make a thin film of the specimen (blood) and leave to air dry.
- dip the smear (2-3 dips) into pure methanol for fixation of the smear, leave to air dry for 30seconds.
- Flood the slide with 5% Giemsa stain solution for 20-30 minutes.
Is it important that the smear is thick in order to ensure that the stain will be retained on the slide?
Water is applied to the slide before emulsifying cells from a solid medium. It is important that the smear is thick in order to ensure that the stain will be retained on the slide.
What is the purpose of the smear preparation?
The preparation of a smear is required for many laboratory procedures, including the Gram-stain. The purpose of making a smear is to fix the bacteria onto the slide and to prevent the sample from being lost during a staining procedure. A smear can be prepared from a solid or broth medium.
Is it better to have thin or thick blood?
For the heart and circulatory system, though, thinner, more watery blood might be better. Some tantalizing threads of evidence suggest that people with thicker (or more viscous) blood have higher chances of developing heart disease or having a heart attack or stroke.
What is difference between thin and thick film?
Thin film has a thickness in the order of 0.1 um (micrometer) or smaller, while thick film is thousands times thicker. However, the main difference is the method used to apply the resistive film onto the substrate. … Thin film is more accurate, has a better temperature coefficient and is more stable.
How do you adjust the thickness of a smear for high hematocrit?
Working with Blood with High Hematocrit Levels You must push more slowly to ensure that the blood spreads far enough down the slide. Using a larger drop size can help get enough blood to spread the desired two-thirds to three-fourths of the length of the slide. You can also change the angle of the pusher slide.
What could affect the quality of a smear?
If the smear is overheated during heat fixing, the cell walls will rupture. Concentration and freshness of reagents may affect the quality of the stain. Washing and drying of the smear between steps should be consistent. Excess water left on the slide will dilute reagents, particularly Gram’s iodine.
Why is thick blood film not fixed?
Thick films are a concentration method. … Thick films should not be fixed with methanol (or direct heat). During the aqueous staining procedure the unfixed RBC lyse, leaving the remains of WBC and any malaria parasites present behind. If thick films are fixed before staining they will be too dense to examine.
How do you adjust the thickness of a blood smear?
Thick smear • Use smaller drop of blood. Decrease the angle of the spreader slide. Increase the speed of the spreader slide. Thin smear • Use a larger drop of blood.
Whats the advantage of a blood smear compared to a CBC?
Unlike automated tests (such as a CBC), a technician or healthcare provider looks at a blood smear under the microscope in order to detect a wide range of changes that give clues to underlying diseases.
Why is a good blood smear necessary for accurate counts?
From the clinical standpoint, blood smear examination serves 3 important objectives. First, it serves as a quality control tool in verifying the results generated by the automated analyzers. Second, it allows for identification of abnormal/immature/atypical cells, if present.
What if malaria test is negative?
If your results were negative, but you still have malaria symptoms, you may need retesting. The number of malaria parasites can vary at times. So your provider may order blood smears every 12-24 hours over a period of two to three days. It’s important to find out whether you have malaria so you can get treated quickly.
How is malaria prevented?
- Apply mosquito repellent with DEET (diethyltoluamide) to exposed skin.
- Drape mosquito netting over beds.
- Put screens on windows and doors.
- Treat clothing, mosquito nets, tents, sleeping bags and other fabrics with an insect repellent called permethrin.
Why heparin and citrate is not recommended to use for the preparation of peripheral blood film?
Heparin (green top tube) is not recommended as an anticoagulant for cell counts, because the cells clump in heparin, invalidating counts. Citrate (blue top tube) is not recommended due to the dilution of the blood by the liquid citrate.
Why is it important not to use thick or dense bacterial smears?
Why is it important not to use thick or dense bacterial smears? The cells will be too concentrated, making it difficult to visualize individual cells and to determine cellular morphology. The stain may not be able to penetrate a thick smear.
Why would gram-positive appear gram-negative?
If the decolorizing agent is applied on the cell for too long time, the Gram-positive organisms to appear Gram-negative. Under-decolorization occurs when the alcohol is not left on long enough to wash out the CV-I complex from the Gram-negative cells, resulting in Gram-negative bacteria to appear Gram-positive.
What happens if you over Decolorize in the Gram stain procedure?
Over-decolorizing will lead to an erroneous result where gram-positive cells may stain pink to red indicating a gram-negative result, and under-decolorizing will lead to an erroneous result where gram-negative cells may appear blue to purple indicating a gram-positive result.
What is smear study?
A blood smear is a blood test used to look for abnormalities in blood cells. The three main blood cells that the test focuses on are: red cells, which carry oxygen throughout your body. white cells, which help your body fight infections and other inflammatory diseases.
Which stain is used for Pap smear?
Papanicolaou stain (also Papanicolaou’s stain and Pap stain) is a multichromatic (multicolored) cytological staining technique developed by George Papanicolaou in 1942. The Papanicolaou stain is one of the most widely used stains in cytology, where it is used to aid pathologists in making a diagnosis.
What is the use of the Giemsa stain in immunology?
It is used to stain the blood cells of hematopoietic tissues. It can also be applied to all tissue sections in which the presence of microorganisms is suspected.
Why Giemsa stain is used for malaria?
It can be used to study the adherence of pathogenic bacteria to human cells. It differentially stains human and bacterial cells purple and pink respectively. It can be used for histopathological diagnosis of the Plasmodium species that cause malaria and some other spirochete and protozoan blood parasites.
