How to Read TB Skin Test

In the earlier article we have already read about what is TB Skin Test and what to do in such circumstances. In this article I am going to show you how to read the TB Skin Test. This will help you to have an idea to read the test report of TB Skin Test. But be careful and trust only on the doctor where you’ve done the test and do as per the suggestion given to you by the doctor.

What is the Method to Read TB Skin Test?

Here reading a TB Skin test means inspecting the thickened area of the skin reaction. This small local area is termed as Induration. Remember Induration is the key to detect and not the red area that comes over there or the brushing.

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Also Skin test should be read somewhere between 2-3 days (48-72 hours) after the injection was done at the doctor’s clinics. At this time this area, termed as Induration is maximum.

Test read after 72 hours may lead to inaccurate results and will tend to incorrect estimation of the size of the Induration. So it is always suggestible to avoid such occurrences.

How TB Skin Tests are interpreted:

As we discussed above, the basis of reading the TB Skin test is the presence or absence of Induration. The diameter of Induration should be measure correctly. It should be measured perpendicularly to the long axis of the forearm. This should be measured in millimeter. You can estimate the criticality of this measurement by its unit itself.

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A tuberculin reaction can be divided as Positive or Negative. This is been considered as a healthy person has Induration greater than 15 mm.

For normal people an Induration greater than or equal to 15 mm is considered as positive. But this 15 mm is not fixed for the entire group of people and in all the cases. For example-

• An Induration of 5 mm is considered as positive for HV infected people.

• Induration of 10 mm is considered as positive for children less than 4 years.

So proper care should be taken care of while reading TB Skin Test.

Also a Negative TB Skin test result doesn’t guarantee that person is free of Tuberculosis. So take the suggestion of the good doctor.

The below flow diagram is depicting the two step Tuberculin Skin Testing.

Conclusion

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I hope this article on How to Read TB Skin Test will help you to understand the TB Skin Test report carefully. With this you can get an idea about the issue and can take the quick precaution.

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