TB Testing

The TB skin test is also called the
Mantoux tuberculin skin test (TST)

A TB skin test requires two visits with a health care provider.
On the first visit the test is placed; on the second visit the health care provider reads the test.

Administering the TB skin test

• The TB skin test is performed by injecting a small amount of fluid (called tuberculin) into the skin on the lower part of the arm.
• A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm.
• The result depends on the size of the raised, hard area or swelling.
• 

  Reading the result of a TB skin test

  Positive skin test: This means the person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease.

  Negative skin test: This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.

  There is no problem in repeating a TB skin test. If repeated, the additional test should be placed in a different location on the body (e.g., other arm).