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Quick GuideBacterial Infections 101: Types, Symptoms, and Treatments
How is the tuberculosis skin test administered?
The standard recommended tuberculin test, known as the Mantoux test, is administered by injecting a 0.1 mL of a liquid containing 5 TU (tuberculin units) of PPD into the top layers of skin (intradermally, immediately under the surface of the skin) of the forearm. The use of a skin area that is free of abnormalities and away from veins is recommended. The injection is typically made using a 27-gauge needle, and a tuberculin syringe. The tuberculin PPD is injected just beneath the surface of the skin. A discrete, pale elevation of the skin (a wheal) 6 mm-10 mm in diameter should be produced when the injection is done correctly. This wheal or "bleb" is generally quickly absorbed. If it is recognized that the first test was improperly administered, another test can be given at once, selecting a site several centimeters away from the original injection.