What does a serological blood test show?
What does a serological blood test show? Diagnostic measures are the most important stage in the treatment of any disease. The success of treatment depends not only on the prescribed drugs, but also largely on how correctly the diagnosis was made.
In addition, the diagnosis prevents complications and comorbidities. Using a serological analysis of the patient's blood, the presence of antibodies and antigens is detected. The study helps to find many diseases, determine their phase and control the course of treatment.
What is serology?
Serology is the branch of immunology that studies the response of antigens to antibodies. This section of medicine deals with the study of blood plasma and its immunological characteristics.
Today, a serological blood test for antibodies is a reliable way to detect human immunodeficiency virus, hepatitis, brucellosis, STDs and other life-threatening diseases.We will understand in what cases it is prescribed.
Indications for appointment
Serological blood test is needed to identify the causative agent of the disease in case of difficulties in diagnosis.
To carry out this reaction, antigens of pathogens are introduced into the plasma, and then the process proceeds is studied by a laboratory technician. Alternatively, a reverse reaction is performed: antibodies are injected into the infected blood to determine the specific affiliation of the pathogen.
Scope of application
This study is used in various branches of medicine. Using this reaction, specific cells and antibodies are produced by the body in order to fight infections and viruses.
In addition, using the serological method is determined by the blood group of the person.
Such a serological examination of a blood test is used in gynecology for the diagnosis of sexually transmitted diseases. This method is also practiced for comprehensive examinations of pregnant women (detection of toxoplasmosis, HIV, syphilis, etc.). Passing this test is required when registering with the antenatal clinic.
In children, a serological reaction is used to confirm the diagnosis of so-called “childhood” diseases (chickenpox, measles, rubella, etc.) if the symptoms have no pronounced manifestations and it is impossible to detect the disease by analyzing the clinical indications.
Detection of sexually transmitted diseases
For venereologists, this testing is truly indispensable and allows you to make a diagnosis very accurately.
With a blurred clinical picture, a serological blood test for syphilis, giardiasis, ureaplasmosis, chlamydia, herpes and other diseases allows you to quickly detect the presence of antibodies.
Viral and infectious diseases
Serological analysis is actively used by gastroenterologists, hepatologists and infectious disease specialists for the diagnosis of viral hepatitis.
The therapist may also order this test to be performed in case of suspected infectious or viral diseases. In order to confirm the diagnosis, a serological analysis of blood for parasites is carried out in order to determine specific antibodies. This is done with encephalitis, brucellosis, allergic reactions.
Decoding a serological analysis of blood makes it possibledetermine the stage of the disease and answer the question of how necessary hospitalization at the moment. How to prepare?
Preparation for the analysis
Serological blood tests are done in state and commercial clinics. Preference should be given to the laboratory, which has modern equipment and qualified personnel.
Biological samples for research can be saliva and feces, but in most cases the patient’s venous blood is used. Blood for serological test taken from the cubital vein in a laboratory. Before taking the test, you should consult with your doctor about the preparation for this procedure.
To prepare for the delivery of the analysis for serological research, you need to follow a few simple rules.
The blood is passed in a calm state before eating, that is, on an empty stomach. Before this, you should not undergo other studies, such as x-rays, ultrasound, etc.
It is necessary to exclude the intake of antibacterial and some other drugs for several weeks before donating blood. Certain recommendations in this case depend on the disease for which the test is done.For example, a study on hepatitis involves the exclusion of fatty foods and alcohol 48 hours before the procedure.
Among the varieties of serological reactions there is a fluorescence reaction. According to this method, the reagent is used, highlighting the antibodies in the serum.
The formulation of a direct serological reaction involves the labeling of specific antibodies with a fluorescent substance. This reaction is the fastest and is carried out in one stage.
Another option for carrying out such an analysis is called indirect, or RNIF. It is carried out in two stages. At the first stage, antibodies are not labeled with fluorescent labels, and at the second stage, respectively, marked antibodies are used to identify antigens and antibodies. Glow occurs only after binding to a specific antibody occurs.
What does a serological blood test show? The result of the whole procedure is evaluated by a special device that analyzes the radiation power, reveals the shape and size of the object under study. The causative agents of infectious diseases are detected with the result, the reliability of which is 90-95%, depending on the type and stage of the pathology.
Linked immunosorbent assay
In these types of serological studies used unique stable reagents. Marked substances are glued to the desired antibodies. As a result, we get a qualitative or quantitative result.
If there are no marked markers, the result will be considered negative. If the presence of antibodies in biological samples is detected by a qualitative study, the result of the analysis is considered positive. In the quantitative determination of cell analysis gives a more accurate result.
Analyzing the indicators of the analysis (for example, the sum of the detected cells), the specialist determines whether the disease is at an early stage, in an acute stage, or if the chronic form of the pathology has worsened. In order to make a diagnosis, the doctor takes into account not only the data of serological research, but also the clinical picture of the disease.
Features of this test
Conducting this analysis is not always able to give a 100% certainty that a particular disease has been detected. It so happens that the results can be mixed and other procedures are required.
For example, during a brucellosis study, blood serum is monitored for self-delay without antigen. This significantly increases the reliability of testing. A test for brucellosis can be positive or negative, as well as in doubt.
When obtaining doubtful results that do not have an unambiguous interpretation, it is recommended to repeat the analysis. In addition, brucellosis can be identified as a result of blood cultures, examining the bone marrow and cerebrospinal fluid.
Pros of serological blood analysis
Diagnostic techniques using serological reactions are widely used in modern medical practice. This is especially done when determining viral and infectious pathologies.
The same analyzes are used in geographic screening and medical examinations to prevent the epidemiological spread of infection.
The advantages of the method include:
- High level of confidence.
- Prompt response and results. The results of RSK are known already after 24 hours. With a special situation, in a hospital, the analysis will be ready in a few hours.
- Controlling the development of the disease and the effectiveness of the therapy.
- Low cost and availability for patients.
Cons of the method
However, serological studies have their drawbacks.
These include the fact that the analysis should take into account the incubation period of the disease in order to get a more reliable picture.
For example, the definition of herpes simplex of the first or second type is possible only after 14 days from the moment of infection. The analysis for the presence of immunodeficiency virus is carried out after 30 days, after 90 days and six months after contact with an infected person.
Of course, the human factor can also affect the accuracy of the results: neglect of the rules of preparation for blood sampling or an error made by a laboratory assistant during the reaction.
According to statistics, an erroneous result can be obtained in 5% of cases. An experienced doctor in the examination of the patient, having studied the clinical picture, in most cases can calculate the error.