NHA Certified Clinical Medical Assistant (CCMA)Foundational Knowledge and Basic ScienceHard
A medical assistant is preparing a patient for a tuberculosis (TB) skin test (Mantoux test). Which of the following is the correct route and angle for administering this injection?
- AIntravenous, 25-degree angle
- BIntramuscular, 90-degree angle
- CSubcutaneous, 45-degree angle
- DIntradermal, 10-15-degree angle
Show answer & explanationAnswer & explanation
Correct answer: D. Intradermal, 10-15-degree angle
The Mantoux test requires an intradermal injection, meaning the medication is injected into the dermis layer of the skin. This is achieved using a very shallow angle of 10-15 degrees to create a visible wheal.
Why the other options are wrong
- A. Intravenous injections are given directly into a vein, typically at a 25-degree angle, and are not used for TB skin tests.
- B. Intramuscular injections are given into the muscle at a 90-degree angle, not for TB tests.
- C. Subcutaneous injections are given into the fatty tissue below the skin at a 45-degree angle, not for TB tests.
Intradermal Injection
An injection administered into the dermis (the layer of skin just below the epidermis), typically used for allergy testing, TB testing, and local anesthetics.
- Angle of administration: 10-15 degrees.
- Forms a small wheal (bleb) on the skin surface.
- Smallest volume of injection among common routes.
Memory trick: ID: 'Into Dermis' at a 'Dinky' 10-15 degrees.