A nurse is preparing to administer an injection to a patient who requires a small volume of medication for allergy testing. Considering the characteristics of different injection routes, which action should the nurse prioritize to ensure the correct technique for this intradermal injection and accurate results?

A. Use a transdermal patch to apply the medication over a hairless skin site for continuous absorption is incorrect because transdermal administration provides systemic, slow, continuous absorption, which is not appropriate for allergy testing. Allergy testing requires localized, controlled exposure to a very small amount of allergen within the dermis, not transdermal absorption through a patch. B. Deliver the medication intramuscularly at a 90° angle into a large muscle to allow rapid absorption of the medication is incorrect because intramuscular (IM) injections deliver medication deeply into muscle tissue, where it is absorbed quickly into systemic circulation. This route would not allow the localized skin response needed for diagnostic allergy testing and could cause systemic reactions, making the results invalid and unsafe. C. Administer the medication subcutaneously at a 45° angle into the fatty tissue to promote slow absorption is incorrect because subcutaneous injections deposit medication into adipose tissue beneath the dermis. This route still results in systemic absorption and will not stimulate the localized, visible wheal (bleb) required to evaluate hypersensitivity reactions. A subcutaneous injection will not produce accurate allergy test results. D. Inject the medication intradermally at a 10–15° angle and observe for a small bleb formation on the skin is correct because intradermal injections place the medication directly between the epidermis and dermis, where immune cells can react locally. This creates a controlled environment for observing skin hypersensitivity. A small bleb or wheal confirms correct placement in the dermis and is essential for accurate interpretation of allergy tests such as tuberculin or allergen sensitivity testing. Maintaining the proper angle (10–15°) ensures shallow placement and reduces the risk of injecting too deeply, which would invalidate the test.