A nurse administers a purified protein derivative skin test. Which action by the student requires follow-up?

• A. Inserts the needle bevel up at a 15-degree angle
• B. Instructs the client that the test will be read in 48-72 hours
• C. Selects a site 3 to 4 finger widths below the antecubital space
• D. Administers the test using a 20-gauge needle, 2 inches long

Answer: (D)

The main idea tested is how to correctly perform a purified protein derivative skin test (Mantoux test) intradermally. This test requires a small-gauge, short needle to deliver about 0.1 mL of tuberculin just under the epidermis to form a tiny bleb. Proper technique includes inserting bevel up at a shallow angle so the needle stays in the dermal layer, selecting the inner forearm about 3–4 finger-widths below the elbow, and reading the reaction 48–72 hours later. Using a needle that is too large and long, such as a 20-gauge needle that’s 2 inches, risks delivering the substance deeper than the dermis (potentially intramuscular), which can alter the test result and cause unnecessary injury. That action requires correction and follow-up to ensure the intradermal delivery is performed with an appropriate needle size and depth.