Medical Surgical Tuberculosis #2

Question

The clinic nurse reads the client’s Mantoux test as positive. What does a positive Mantoux test indicate?

Answers

  1. The client is immune to tuberculosis.
    • Rationale:

      This answer is not correct because a mantoux test does not measure immunity, but rather the degree of hypersensitivity to tuberculin. A positive Mantoux test indicates that the client has been exposed to the Mycobacterium tuberculosis.

  2. The induration is at least 2 mm.
    • Rationale:

      This answer is not correct because an induration of 2 mm indicates a negative result. For a mantoux test to be considered positive, there must be an induration of at least 5 mm or greater.

  3. The client has an active case of tuberculosis.
    • Rationale:

      This answer is not correct because a positive TB skin test does not indicate active tuberculosis. In order for a diagnosis of active tuberculosis to be made, the client must have three positive sputum culture results.

  4. The client has been exposed to the Mycobacterium tuberculosis.
    • Rationale:

      This answer is correct because a positive Mantoux test means that the client has been exposed to the Mycobacterium tuberculosis. A diagnosis of latent tuberculosis may be made if the client has a positive TB skin test but further medical evaluation rules out active TB.

Overview

The focus of this question is correctly identifying the meaning of a positive TB skin test (Mantoux test). A positive TB skin test does not mean that the client has an active tuberculosis infection. Definitive diagnosis of TB is made with a series of sputum cultures. A positive Mantoux test indicates that the client has been exposed to the Mycobacterium tuberculosis.

Explanation

Learning Outcomes

A mantoux test (TB skin test) is a diagnostic tool used for identifying exposure to tuberculosis. A TB skin test is considered positive if 48-72 hours after the injection, there is a positive induration of at least 10 mm. However, a positive TB skin test does not mean that a client has active tuberculosis but rather it represents exposure to the Mycobacterium tuberculosis.

Test Taking Tip

It is essential to understand how definitive diagnosis of TB is made. This is a highly tested topic both in nursing school and on NCLEX.

Video Rationale