Mantoux test - all the features of the method

The Mantoux test refers to diagnostic laboratory tests. It is performed in children for the purpose of prevention and early diagnosis of tuberculosis . Let us consider in more detail the method, the peculiarities of its conduction, and dwell on the evaluation of the results obtained.

Mantoux sample composition

The composition of the tuberculin sample is complex. The basis of the drug is tuberculin. It is made from a mixture of culture of mycobacteria of human and bovine type. Preliminarily, they are inactivated during the thermal treatment, then purified by ultraviolet and precipitated with trichloroacetic acid. The final stage of preparation is treatment of the mixture with ethyl alcohol and ether. These components play a preservative role.

In addition to the current base, tuberculin, the Mantoux test contains:

Mantoux test - when do?

It must be said that this sample suggests a response to the introduction of tuberculin into the body. At the injection site, a small inflammation focus is formed. Immediately its dimensions are evaluated after the procedure. The first Mantoux test is carried out 12 months after the birth of the crumbs. An early test, at 2 months, is permissible when BCG vaccination was not performed in the hospital.

Often, difficult births, fetal conditions do not allow the introduction of a vaccine. In such cases, before the formulation of BCG, a tuberculin test is preliminarily done, Mantoux. It allows you to exclude the infection of the child with a stick of Koch. After this, the study is conducted annually, 1 time. If the reaction to the introduction of tuberculin increases, the parents of the baby or his loved ones who are in contact with him, identified a stick of Koch , the sample is carried out 2-3 times a year.

Technique of Mantoux test

A special syringe is used to perform this test. The drug is injected intradermally, into the middle third of the inner surface of the forearm. Preliminary preparation is not required, it is carried out at any time. Doctors inform parents in advance that the child will be tested Mantoux, whose algorithm is as follows:

  1. A cotton wool soaked in an antiseptic treats the area of ​​administration.
  2. The needle is turned upwards, the skin is slightly stretched.
  3. The needle hole is completely inserted into the skin, lifting slightly upward and injecting the drug.
  4. After that, a small swelling is formed, which disappears after a few minutes.
  5. The dose of the drug in the Mantoux sample is 2 TE (tuberculosis units), which are contained in 0.1 ml.

Mantoux test results

After the Mantoux test is carried out, the result is evaluated after 72 hours. At the injection site, a papule is formed. Directly its size is of diagnostic importance. Externally, this compaction is rounded, towering above the surface of the skin. It is the result of the saturation of the skin with sensitized lymphocytes.

With a slight pressure on the papule, it acquires a whitish hue. Sample sizes are evaluated using a transparent ruler, with good lighting. It is installed transversely to the forearm. In doing so, calculate the size of the seal itself, not taking into account the red bezel. It is the result of the body's reaction to the introduction of the pathogen, is the norm. After the Mantoux test is carried out, the evaluation of the result in children is carried out exclusively by the pediatrician.

Negative Mantoux test

When an evaluation of the Mantoux test is performed, doctors rarely record a negative result. This is said if the size of the papule is not more than 1 mm or it is completely absent. He points out that the causative agent never entered the body earlier or the infection occurred 10 weeks ago, no more. This result may indicate a lack of vaccination for BCG in the maternity hospital.

Doubtful Mantoux test

The Mantoux test, the norm of which is described below, may have a dubious result. This is said at a papule size of 2-4 mm. Also, with such a reaction, only a slight redness is possible. The latter also occurs when the injection site comes into contact with water. A doubtful result requires a re-diagnosis in a short time, for an accurate result.

Positive Mantoux test

The tuberculin test is considered positive when the seal size is 5-16 mm. This result indicates the presence of active immunity to the causative agent of tuberculosis. Changing this reaction helps determine if a child has been infected before. In addition, a positive result is seen in children previously vaccinated with BCG. The following variants of the positive sample are distinguished:

The first positive reaction to tuberculin may indicate primary infection. However, even such a result is not used to make a diagnosis - it requires observation and repetition of the sample in a short time. In children 2-3 years of age, a positive Mantoux test can be regarded as a postvaccinal allergy, which requires careful, differential diagnosis.

The diagnosis of the "turn of the tuberculin test" - what is it?

The term "turn of a tuberculin test" is used to designate a situation in which a negative result of the study turns positive. In this case, the following characteristic signs, criteria that are used in the diagnosis are distinguished:

It is worth noting that the sample itself does not allow you to make conclusions about the transferred disease. In some cases, an increase in the pouch formed at the injection site is the result of an allergic reaction. To exclude a variant of infection, doctors conduct additional diagnostics after a while. Often, the bend of a tuberculin test in children indicates a history of tuberculosis over the past year.

Complications of tuberculin test

The tuberculin test of Mantoux is a procedure in which weakened cells of the pathogen are introduced into the body. Because of this, complications are possible. A frequent consequence of the introduction of tuberculin to children is an allergic reaction. Among other side effects, it is necessary to distinguish:

Mantoux test - contraindications

The Mantoux test in adults is not carried out because of its uninformativeness. It is not always possible for children. Like any drug, tuberculin has contraindications to use. If they are available, the research is postponed indefinitely. The Mantoux test is not possible when:

Alternative to the Mantoux sample

Due to the fact that the Mantoux test is not always possible, doctors use alternative methods of diagnosing tuberculosis. Among actively used:

Both methods involve taking a sample of venous blood for examination. So, when carrying out the immunogram, doctors determine how many cells are produced to fight the infection. The results assess the ability of the body to resist the pathogen. The disadvantage is the impossibility to establish a complete picture of the circumstances of infection, to determine the presence of the disease at the moment.

Suslov's test is based on the study of a blood sample in which tuberculin is added. After a while, the condition of the blood corpuscles is assessed under a microscope. The method does not have 100% informative value. He helps doctors only to guess the possible infection with a stick of Koch. Because of this, at the first opportunity, a Mantoux test is performed that can detect the disease.