When administering purified protein derivative (PPD) for suspected tuberculosis, what should the nurse ensure during the injection?

When administering purified protein derivative (PPD) for suspected tuberculosis, it is essential that the injection produces a wheal on the skin. This localized swelling, or wheal, indicates that the PPD has been correctly administered intradermally, which is the preferred route for this test. The formation of the wheal is a sign that the epidermis and the upper layers of the dermis have been appropriately penetrated. This reaction occurs because the PPD is provided in a small volume, typically 0.1 mL, which is intended to be injected into the intradermal layer, causing a localized response that can be read for interpretation typically 48 to 72 hours later.

Administering the injection into the muscle or into a large volume can lead to complications and an inaccurate reading, as the PPD must remain in the dermal layer to stimulate the correct immune response. Massaging the site is also contraindicated, as it could disperse the PPD, altering the local reaction and affecting the test results. Thus, ensuring a wheal formation is crucial for accurate tuberculosis screening.