Certified Medical Assistant (CMA AAMA)PharmacologyEasy
A medical assistant is preparing to administer 0.25 mL of purified protein derivative (PPD) for a tuberculin skin test. Which of the following sites is the most appropriate for this injection?
- AUpper outer arm
- BVastus lateralis
- CDeltoid muscle
- DVentral forearm
Show answer & explanationAnswer & explanation
Correct answer: D. Ventral forearm
Tuberculin skin tests are administered intradermally, and the ventral forearm is the preferred site due to its accessibility, lack of hair, and thinner skin, which allows for easier observation of the reaction.
Why the other options are wrong
- A. Upper outer arm is a common site for subcutaneous and intramuscular injections, but not for intradermal PPD.
- B. Vastus lateralis is an intramuscular site, inappropriate for PPD.
- C. Deltoid muscle is an intramuscular site, inappropriate for PPD.
Intradermal Injection Site
Intradermal injections are given into the dermal layer of the skin, just below the epidermis. The ventral forearm is the most common site due to its thin skin and easy visibility for reaction assessment.
- Common for allergy tests and PPD (TB) tests.
- Small volume (0.01-0.1 mL) is injected.
- Forms a wheal or bleb on the skin surface.
Memory trick: Many Routes, Many Spots