During PPD testing, which statement describes the correct technique to perform the test?

• A. Ensure the wheel forms
• B. Point the bevel of the needle downward
• C. Massage the area after the injection
• D. Use a 22 gauge, one-inch needle

Answer: (A)

The key idea is that tuberculin skin testing must be done intradermally so the antigen sits in the dermis and forms a small bleb, or wheel, at the site. That wheal indicates the injection was placed correctly in the dermal layer. To achieve this, the needle is used with the bevel oriented up so the injection deposits just beneath the skin surface and creates the characteristic wheal. Poking with the bevel downward would tend to place the material deeper and fail to produce the proper wheal. Avoid massaging the area after the injection, since rubbing can spread the antigen and alter the reading. And using a larger gauge and longer needle, like a 22-gauge, one-inch needle, increases the chance of going deeper than the dermis and is not appropriate for intradermal delivery.