In tuberculin skin test (mountex test), endurance of erythema or result interpretation should be done in?

NORCET 3 - 2022 (Shift-2)

Medical & Surgical Nursing

Easy

Appeared in: NORCET 3 - 2022 (Shift-2)

Explanation

The Mantoux test measures a delayed-type hypersensitivity reaction to tuberculin antigens.
This immune reaction typically begins 5-6 hours after injection but takes 48 to 72 hours to reach its maximum induration (firm swelling).
Reading the test within this specific window is critical for accuracy and to avoid false-negative results.
The result is based on the diameter of the induration, not the erythema (redness).

Option A: Reading the test at 24 hours is too early. The delayed-type hypersensitivity reaction has not yet fully developed, which would likely result in a false-negative reading.
Option C: This is far too soon to read the test. At 12 hours, the specific cell-mediated immune response measured by the test has barely begun.
Option D: This option is imprecise and potentially misleading. While the test is read at a time that is less than 72 hours, this option also includes incorrect early time points like 12 or 24 hours. The standard of care requires the specific 48-72 hour window.

Visual 1: Diagram - An illustration showing a forearm with a positive Mantoux test result. It should clearly label the induration and erythema, with a ruler measuring the transverse diameter of the induration.
Visual 2: Infographic - A chart summarizing the interpretation of the Mantoux test, showing the different induration size cutoffs (≥5 mm, ≥10 mm, ≥15 mm) and the corresponding patient risk groups for each cutoff.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The concept tested is the correct procedure for interpreting the Tuberculin Skin Test (Mantoux test), specifically the timing for reading the result as background academic context rather than a clinical decision trigger.
A nurse's primary role includes administering the PPD, instructing the patient on when to return for the reading, and accurately measuring and documenting the result.
Patient education is crucial. The nurse must explain that the test needs to be read in 2-3 days and that it is the hardened, raised area that will be measured, not just the redness.
A positive test does not necessarily mean active TB disease; it indicates that the person has been infected with TB bacteria. Further tests like a chest X-ray and sputum sample are needed to diagnose active TB.

How to Approach the Question

First, identify the core of the question: it asks for the specific time frame for reading a Mantoux test.
Recognize that this is a factual recall question based on a standard clinical procedure.
Evaluate the options. Notice that '12 hours' and '24 hours' are likely too short for a 'delayed' hypersensitivity reaction.
Compare '48-72 hours' and '<72 hours'. The option '48-72 hours' provides a specific, actionable window, which is typical for medical protocols. '<72 hours' is vague and less precise.
Select '48-72 hours' as it represents the standard, evidence-based time frame for maximal reaction and accurate interpretation.

Concept Tested & Keywords

Concept Tested: The concept tested is the correct procedure for interpreting the Tuberculin Skin Test (Mantoux test), specifically the timing for reading the result.
Stem keywords: tuberculin skin test, mountex test, result interpretation
Lead-in keywords: should be done in
Negative lead-in flag: false

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