Which one of the following is an intradermal test?

RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Fundamental of Nursing

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-1)

Explanation

The MT test, also known as the Mantoux test or Tuberculin Skin Test (TST), is a standard method for screening for tuberculosis (TB).
The procedure involves injecting a small amount (0.1 mL) of Purified Protein Derivative (PPD) into the dermis, which is the layer of skin just below the epidermis.
This intradermal injection is designed to elicit a delayed-type hypersensitivity reaction in individuals who have been previously sensitized to Mycobacterium tuberculosis.
A positive reaction, indicated by a firm, raised area called an induration, suggests a TB infection (latent or active).

Option B: The Allen test is a physical assessment, not an injection. It evaluates collateral blood flow to the hand by compressing the radial and ulnar arteries.
Option C: The Tourniquet test is a clinical sign assessment that uses a blood pressure cuff to check for capillary fragility. It does not involve any injection.
Option D: This option is incorrect because the Allen test and Tourniquet test are not intradermal procedures. Only the MT test fits the description.

Visual 1: Diagram: A cross-section of the skin showing the correct 5-15 degree angle for an intradermal injection, with the needle tip entering the dermis to form a wheal.
Visual 2: Image Series: A comparison of a positive Mantoux test (significant, palpable induration) versus a negative test (no induration) to aid in visual assessment and accurate reading.
Visual 3: Flowchart: Steps for performing the Allen test, showing hand compression and observation of color return.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Identification of intradermal diagnostic tests as background academic context rather than a clinical decision trigger.
Correct administration technique is critical for the Mantoux test. If the PPD is injected too deeply (subcutaneously), it can lead to a false-negative result, potentially delaying the diagnosis and treatment of tuberculosis.
Nurses are primarily responsible for accurately reading the test result by measuring the diameter of the induration (not the redness) 48-72 hours post-injection and documenting it correctly as per institutional and national guidelines (e.g., NTEP in India).
What if? If a patient is severely immunocompromised (e.g., advanced HIV, on high-dose steroids), they may not be able to mount an immune response, leading to a false-negative Mantoux test even if they have active TB. In such cases, an Interferon-Gamma Release Assay (IGRA) blood test or other diagnostic methods should be considered.

How to Approach the Question

First, define the key term in the question: 'intradermal test'. This is an injection given into the dermis, the layer of skin just beneath the surface.
Next, evaluate each option based on this definition.
Recall or deduce the purpose and procedure for each test. The MT test is a skin test for TB. The Allen test checks blood flow in the hand. The Tourniquet test checks for capillary bleeding.
Identify that only the MT test involves an injection into the skin layer.
Eliminate the other options as they are physical assessments or involve pressure application, not intradermal injection.
Conclude that the MT test is the only correct answer.

Concept Tested & Keywords

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