Blood smear examination is a fairly common method that allows you to quickly diagnose many common disorders. The main conditions for the effective use of this diagnostic method are strict adherence to the smear preparation technique and a systematic study in compliance with the algorithm.
In practice, it is far from always possible to obtain objective data within the framework of using hematological rapid diagnostics. The study of a blood smear makes it possible to relatively quickly clarify and supplement the information received. This technique allows you to identify some elements that do not appear during clinical automated studies, for example, a change in the erythrocyte shape along with a shift in the leukocyte index to the left, that is, towards an immature neutrophil, or the presence of parasites. In some situations, this technique allows a definitive diagnosis.
Research algorithm
He's next:
- Immediately after sampling, blood must be quickly placed inanticoagulant tube to maintain cell quality.
- Methylene blue stain allows identification of reticulocytes.
- Evaluation is carried out on a thin layer of a smear with a reading at the level of its pigtails under a microscope.
- By conducting a systematic examination of a blood smear, the APEL algorithm is meant.
What is this analysis used for?
For such purposes:
- As part of determining irregularities in shape and size, as well as changes in the number of red blood cells, platelets, white blood cells and various types of blood cells (including any immature forms) along with their percentage.
- For the diagnosis of various diseases associated with impaired education, functions or excessive destruction of the shaped element.
- To track the formation of cells with their degree of maturity in leukemia, after radiation treatment, and also as part of a disorder in the formation of hemoglobin.
When is this study ordered?
In the event that, according to the result of the general analysis and the leukocyte formula (which is prescribed for the widest range of indications), a significant increase in the number of leukocytes, atypical or immature cells is detected, then a blood smear should be taken. Among other things, such a study is important to carry out in a number of such situations:
- Against a background of suspected disease that affects cells.
- When using drugs that can affect their production.
As part of theblood smear analysis, physicians usually use venous or capillary biological fluid.
Preparation
When sampling a biomaterial with an average diameter of a vein expansion, blood should flow quickly into a test tube that contains an anticoagulant. Ethylenediaminetetraacetate is often used because it makes it possible to better preserve the shaped element under study. True, in order to prevent various kinds of morphological cell degradation, the time interval between taking a fresh and well-homogenized biomaterial and preparing the preparation should be as short as possible.
Preparation of smears begins with taking a drop of blood (usually just one from the capillary tube) on the edge of a microscope slide. It is then smeared by means of a second glass element sliding over the first. A well-prepared smear has a so-called "cat tongue" at the end, indicating that the sample was performed correctly and makes it possible to conduct a high-quality examination.
Coloring
Coloring is carried out by the standard method. Before this procedure, the prepared blood smear is dried in air by shaking the glass slide, which makes it possible to avoid the formation of an unstained light zone in the center of the erythrocytes. Due to this, the erroneous interpretation of hypochromia is accordingly excluded.
There may be other coloring artifacts. For example, Wright's stain provides a precipitate. This happens whenthe paint was not renewed after a certain period, the glass slide was in the staining solution for a long time or was poorly washed. As a result, the accumulation of the dye can be interpreted as the presence of parasites and bacteria in the blood. In addition, the staining of a smear with cell morphology can be changed by contacting the slide with formalin vapor. Samples are usually stained according to the Romanovsky method based on methylene blue and eosin.
Classic coloration of blood smears, as a rule, differs significantly from fast. Recently, such methods have their advantages, since they are resistant to variations in the acidity of solutions and the formation of a substance depot. But, nevertheless, they are less effective in detecting polychromatophiles and do not change the color of granules of basophils and mast cells.
In order to obtain a visual specific picture of reticulocytes, staining with new methylene blue is required. In plastic test tubes, a blood drop is mixed with two NBM elements. The tube is left at room temperature for ten minutes. A small drop after mixing is placed on a glass slide and smeared in the same way as during a smear. The slide is then quickly air-dried and examined under a microscope at high magnification.
Systematic study
As part of the evaluation, it is extremely important to be guided by a single research scheme. Microscopy of a blood smear that is performedone thin layer with a rounded tip, thickens towards its base. Cells are evaluated on a thin drawing, as a thick one carries little information. At low magnification, the marginal part of the smear, mainly its rounded end, is usually examined for the detection of platelet aggregates or atypical wide cells (lymphoblasts or dendritic elements).
The layer may have a zigzag or pigtail shape, which allows you to clearly observe various blood cells in an APEL directed study, where A suggests other atypical elements with parasites, P indicates platelets, E indicates erythrocytes, and L about white blood cells.
Blood smear examination is a fairly common technique that allows you to quickly diagnose various common disorders. The main conditions for the effective application of this method are strict observance of the smear examination technique with a systematic analysis in compliance with the procedure algorithm.
What do the results mean?
A change in a blood smear does not always make it possible to make a diagnosis. Usually this indicates the presence of a certain disease, which implies a subsequent examination in order to make an accurate diagnosis.
Rationale for analysis
There is a fairly large range of diseases, and at the same time disorders, against which the properties of cells that circulate in the bloodstream can change. Normally, only mature elements penetrate into this biomaterial from the bone marrow,but in a number of pathologies, for example, in leukemia, immature analogs in the form of blasts can get into it. In some disease states, for example, with massive infections, characteristic impurities may appear in leukocytes, the cells themselves become atypical, as, for example, in infectious mononucleosis.
With a deficiency of iron or vitamin B12, with a congenital disorder of hemoglobin synthesis, the properties and appearance of red blood cells may change. The detection of such pathological cells in an excessive amount in a smear makes it possible to suspect the pathology that caused them and prescribe an additional examination to the patient. A blood smear can be regularly prescribed to people with oncological diseases of the bone marrow or lymph nodes as part of monitoring the dynamics and monitoring the effectiveness of therapy.
