Serological tests: types of procedure, indications for conduction, contraindications

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Infectious diseases initiate the production of antibodies in the blood of a sick person. This is how the body's immune defense works.

Determination of the presence of antibodies to a specific virus or bacteria makes it possible to know about the onset of the disease before its main symptoms appear. Today, serological and bacteriological research gives the most complete picture. Therefore, we'll talk in this article about the analysis for serological research.

What is a serological study of

Methods of studying biological materials of humans and animals that can detect antibodies or antigens that produce an organism in the form of a protective reaction in the fight against infections are called serological studies. Such methods are used to determine the causative agent of infection, and also with the aim of:

  • blood group determination,
  • study of immunity through the determination of its humoral level,
  • determination of tissue antigens.

To whom the serological examination of blood for parasites, HIV, syphilis, antibodies, typhoid, on the markers of infectious diseases is prescribed, read below.

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To whom it is prescribed

Studies are recommended for patients to establish a diagnosis for a wide range of infectious diseases. Serological tests are performed in determining the blood group, as well as to determine the effectiveness of treatment.

Why do it

The method is valued by specialists as a way to make a qualitative diagnosis of the disease.

  • If the patient is at the stage of the disease, then repeated studies are recommended to be carried out at intervals of about a week to observe the effectiveness of the treatment used.
  • Often serological tests are used to determine which pathogen caused the disease after the patient has suffered it.

Types of procedure

Methods of serological testing are based on various reactions:

  • Neutralization reaction relies on the property of antibodies of the immune serum to act as a neutralizing agent for toxins or microorganisms themselves, preventing their damaging effect.
  • The agglutination reaction , which in turn is subdivided into such subspecies:
    • direct reactions - they are used in the study of serum for the presence of antibodies. In the studied composition, the killed microbes are injected and, if a precipitate appears in the form of flakes, this means that the reaction is positive for this type of microbes;
    • the reaction of indirect haemagglutination is made by introducing into the blood serum of red blood cells, on which antigens are adsorbed;these agents come into contact with the same kind of antigens present in the blood serum, as a result of which a scalloped precipitate falls out.
  • Complement reaction is used to detect infectious diseases. The method is realized through complement activation and observation of the occurring reactions in the investigated medium.
  • The precipitation reaction is accomplished by layering the antigen solution onto a liquid medium - the immune serum. Antigen for this method is used soluble. The reaction is that the antigen-antibody complex undergoes precipitation;the resulting precipitate is called precipitate.
  • The reaction using labeled antigens and antibodies is based on the fact that microbes or tissue antigens treated in a certain way receive the ability to emit light under the action of ultraviolet rays. The method is used not only for the diagnosis of antigens, but also for the determination of drugs, enzymes, hormones.

Contraindications for carrying out

Due to the fact that the method consists in studying the patient's biological material, it can not affect a person negatively. Therefore, there are no contraindications to use.

How to conduct a serological study, we will discuss below.

Indications for the

The method is used to determine the causative agent of infection, including in such diseases:

  • cytomegalovirus infection,
  • HIV infection,
  • herpes,
  • toxoplasmosis,
  • inflamed parotid lymph nodes,
  • labyrintopathy,
  • sexually transmitted infections;
  • diphtheria,
  • Epstein-Barr virus,
  • herpes zoster,
  • serum sickness,
  • presence of Staphylococcus aureus in the ears;
  • brucellosis,
  • infectious dermatitis,
  • bullous otitis media,
  • blastomycosis,
  • staphylococcal infections,
  • hepatitis.

The method is also used to detect such diseases:

  • opisthorchiasis,
  • amoebiasis,
  • cysticercosis,
  • giardiasis,
  • pneumonia.

Preparing for the

procedure No special preparation is required for the procedure. One condition should be observed: blood sampling is done on an empty stomach.

The algorithm for sampling( collection) of blood( material) for a serological test is described below.

Conducting the

analysis Blood sampling is made from the ulnar vein. In order for the study to work out, the blood is not collected by a syringe, but by gravity. A needle is inserted into the vein without a syringe and up to 5 ml of blood is collected into the tube.

During the procedure, the patient experiences a slight discomfort during the insertion of the needle into the vein. The following actions do not cause any concern.

The interpretation of the results of a serological blood test is described below.

Interpretation of results

The results obtained should be considered in conjunction with the clinical picture of the disease, an examination of the alleged diagnosis using several tests. This is due to the fact that the studies have a specific character and sometimes do not have absolute sensitivity to infectious diseases.

The price of a comprehensive blood serology test is described below.

The average cost of the procedure

What price of the procedure will depend on the type of study. It consists of the cost of the product of analysis and the cost of antibodies to a particular causative agent of the disease. The average cost of the procedure is within 700 rubles.

Serological reactions are described in the video below:

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