What is the clinical significance of a PPD trial?

The PPD test is a tuberculin test, which is used as an auxiliary test for clinical tuberculosis and the detection of successful BCG vaccination in children. For the diagnosis of tuberculosis, the sensitivity is still very high beyond the processing of x-rays.

The induration of the PPD experiment is shown in the figure below

Suspicious: (t) Redness and induration are below in diameter.

Positive: (+ Redness and induration are redness and stool are redness and induration are above Zcin.) (+ Blisters or necrosis in addition to redness and induration.)

Precautions: Before the examination: It must be diluted to an appropriate concentration for ** test, so as not to cause systemic reactions or aggravate local reactions.

During the examination: should relax and eliminate anxiety and anxiety Unsuitable people: people with active tuberculosis.

Clinical significance. 1. It is used for diagnosis and differential diagnosis.

Tuberculin test plays an important role in the diagnosis and differentiation of tuberculosis in adolescents, children and the elderly, and is an important auxiliary examination method.

2. Provide a basis for BCG vaccination.

If the tuberculin test is positive, it indicates that the body has been infected with tuberculosis bacteria, and there is no need for BCG vaccination. Those who have a negative tuberculin test are eligible for BCG.

3. Provide a basis for measuring the immune effect.

Generally, a tuberculin test is done 3 months after BCG vaccination to find out whether the body develops immunity to BCG. If the tuberculin test is positive, it indicates that BCG vaccination has been successful, otherwise BCG vaccination needs to be repeated.

The above content reference:

Encyclopedia - Tuberculin test.

Encyclopedia - tuberculin intradermal test.

1) After BCG vaccination.

2) Elderly children with no obvious clinical symptoms but only a general positive reaction indicate that they have been infected with Mycobacterium tuberculosis.

3) Positive reactions in infants and young children, especially those who have not been vaccinated with BCG, mostly indicate that there are new tuberculosis foci in the body, and the younger the age, the greater the possibility of active tuberculosis.

4) Strong positive patients show active tuberculosis in the body.

5) When the reaction changes from negative to positive, or the intensity of the reaction increases from less than 10mm to more than 10mm, and the increase exceeds 6mm, it indicates a new infection.

Tuberculin test, also known as PPD test, refers to an intradermal test that diagnoses the type of hypersensitivity caused by Mycobacterium tuberculosis infection by intradermal injection of tuberculin and according to the condition of the injection site. Tuberculin is the cellular component of Mycobacterium tuberculosis, including pure protein derivatives (PPD) and old tuberculin (OT). This test is useful for diagnosing tuberculosis and measuring the body's non-specific cellular immune function.

Commonly used intradermal injection, dosage of PPD: the first test solution contains 1 100,000 times of dilution for the first time generally used, in order to prevent serious ** and systemic reactions. After routine disinfection, the test solution is injected into the skin of the flexor side of the forearm, and the results are observed for 48 72 hours, if the results of 48 hours are not clear, the results of 72 hours should prevail, pay attention to whether there is local induration, and do not take redness as the standard alone.