A blood smear test 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 systematic research in compliance with the algorithm.
In practice, it is far from always possible to obtain objective data in the framework of using hematological rapid diagnostics. A blood smear test allows you to relatively quickly refine and supplement the information received. This technique allows you to identify some elements that are not manifested in clinical automated studies, for example, a change in the red blood cell shape along with a shift in the leukocyte count to the left, that is, towards an immature neutrophil, or the presence of parasites. In some situations, this technique allows you to make a final diagnosis.
Research algorithm
He is as follows:
- Immediately after taking the material, blood must be quickly placed in a tube with an anticoagulant to maintain cell quality.
- Staining with blue methylene makes it possible to identify reticulocytes.
- The assessment is carried out on a thin layer of the smear with reading at the level of its braids under the microscope.
- By a systematic study of a blood smear is meant the APEL algorithm.
What is this analysis used for?
For such purposes:
- As part of the definition of violations of shape and size, as well as changes in the number of red blood cells, platelets, white blood cells and various types of blood elements (including any immature forms), along with their percentage ratio.
- For the diagnosis of various diseases associated with impaired education, functions or with excessive destruction of the shaped element.
- In order to track the formation of cells with the degree of their maturity in leukemia, after radiation treatment, as well as within the framework of hemoglobin formation disorders.
When is this study scheduled?
In the event that, according to the result of the general analysis and the leukocyte formula (which is prescribed according to the widest range of indications), a significant increase in the number of leukocytes, atypical or immature cells is detected, then a blood smear is necessary. Among other things, such a study is important to carry out in a number of such situations:
- Amid suspicion of a disease that affects the cells.
- When using drugs that can affect their production.
As part of the analysis of a blood smear, doctors, as a rule, use venous or capillary biological fluid.
Training
When collecting biomaterial with an average vein expansion diameter, blood should flow quickly into a test tube that contains an anticoagulant. Ethylene diamine tetraacetate is often used because it makes it possible to better preserve the test piece. True, in order to forestall various kinds of morphological degradation of cells, the time interval between taking fresh and well-homogenized biomaterial and preparing the preparation should be as short as possible.
Preparation of smears begins with the collection of a drop of blood (usually just one of the capillary tubes) on the edge of a microscope slide. Then it is smeared by means of a second glass element sliding on the first. A well-prepared smear at the end has the so-called "cat language", indicating that the sample was correctly performed and makes it possible to conduct a quality examination.
Coloring
Coloring is carried out by the standard method. Before this procedure, the blood smear made is dried in air by swaying a glass slide, which makes it possible to avoid the formation of an unpainted light zone in the center of red blood cells. Due to this, the erroneous interpretation of hypochromia is accordingly excluded.
There may be other coloring artifacts. For example, Wright staining provides a precipitate. This happens when the paint is not renewed after a certain period, the glass slide was in the staining solution for a long time or it was poorly washed. As a result, dye accumulation can be interpreted as the presence of parasites and bacteria in the blood. In addition, the stain of the smear with cell morphology can be changed as part of the contact of the slide with formalin vapor. Typically, samples are stained according to the Romanovsky method based on methylene blue and eosin.
The classic color of blood smears, as a rule, is significantly different from fast. Recently, such techniques have their advantages, since they are resistant to variations in the acidity of solutions and the formation of a depot of a substance. But, nevertheless, they are less effective in detecting polychromatophiles and poorly change the color of granules of basophils and mast cells.
In order to get a visual specific picture of reticulocytes, staining with new methylene blue is required. In plastic tubes, a blood drop is mixed with two NBM elements. The tube is left at room temperature for ten minutes. After mixing, a small drop is placed on a glass slide and smeared just like during a smear. Then the slide is quickly dried in air and examined under a microscope with a huge increase.
Systematic research
As part of the assessment, it is imperative to be guided by a single research framework. Microscopy of a blood smear, which is performed in one thin layer with roundness at the tip, thickens to its base. Cells are evaluated in a thin pattern, since a fat one carries little information. With a small increase, the edge of the smear, mainly its rounded end, is usually examined for the detection of an aggregate of platelets or atypical broad cells (lymphoblasts or dendritic elements).
The layer may have the shape of zigzags or pigtails, which allows one to observe quite clearly various blood cells as part of a directed study using the APEL algorithm, where A suggests other atypical elements with parasites, P stands for platelets, E stands for red blood cells, and L for white blood cells.
The study of blood smears is a fairly common technique that allows you to quickly diagnose various common violations. The main conditions for the effective application of this method is strict adherence to the smear study technique with systematic analysis in compliance with the procedure algorithm.
What do the results mean?
A change in blood smear does not always make it possible to make a diagnosis. Usually, this indicates the presence of a certain disease, which involves a subsequent examination with the aim of making an accurate diagnosis.
The feasibility of analysis
There is a fairly wide 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 with a number of pathologies, for example, with leukemia, immature analogues in the form of blasts can enter it. In some painful conditions, for example, with massive infections, characteristic impurities may appear in leukocytes, the cells themselves become atypical, as, for example, with infectious mononucleoses.
With a deficiency of iron or vitamin B 12 , with a congenital violation of hemoglobin synthesis, the properties and appearance of red blood cells can change. Excessive detection of such pathological cells in the smear makes it possible to suspect the pathology that caused them and assign an additional examination to the patient. A blood smear can be regularly prescribed to people with cancer of the bone marrow or lymph nodes as part of monitoring the dynamics and monitoring the effectiveness of therapy.