A tuberculin skin test (TST) is a screening test that is an injection of a small amount of testing fluid (tuberculin PPD) into the inner surface of the forearm. After you receive a TST, you will need to return in 2 to 3 days, so the nurse can check your arm to read your test.
The nurse will look and feel for any measurable swelling in the area of the injection. The most common reasons adults may need a TST are for employment exams or school requirements.