What is the expected outcome when administering an intradermal injection?

When administering an intradermal injection, the expected outcome is the presence of a wheel at the injection site. This occurs because intradermal injections are designed to deposit a small volume of medication into the dermal layer of the skin, which is just beneath the epidermis. The injection creates a localized reaction in which the fluid injected causes the skin to elevate, forming a small, raised area known as a wheel or bleb. This response indicates that the medication has been correctly administered and is typical for tests like tuberculosis skin tests, where a wheel formation is a desired response.

The formation of a wheel is an important clinical indicator that the injection was successful and has been recognized by the body as a foreign substance, potentially leading to an immune response. In contrast, other responses like immediate pain or swelling of the entire arm are not typical outcomes for this type of injection and could indicate complications or adverse reactions. A lack of reaction does not provide the clinician with valuable information about the injection's effectiveness.