TB Test Practice and Application 2

Question 1

A TST is placed on a patient who received BCG vaccination as a child. The induration measures 12 mm. What is the correct interpretation?

Accepted Answer

Disregard BCG history; 12 mm is positive for a standard-risk person

Answer

In the US, BCG history is generally disregarded when interpreting TST because BCG is not routinely used and its effect wanes; 10 mm or more is positive for most standard-risk adults.

Question 2

Which anatomical site is the standard location for placing a TST (Mantoux test)?

Accepted Answer

Volar surface of the forearm

Answer

The Mantoux TST is injected intradermally on the volar (inner) surface of the forearm, 2–4 inches below the elbow.

Question 3

A healthcare worker's TST shows 9 mm induration. She has no known risk factors. How should this result be classified?

Accepted Answer

Negative, because the threshold for healthcare workers is 10 mm

Answer

For healthcare workers without additional risk factors, 10 mm or more is the positive threshold; 9 mm is therefore negative.

Question 4

What is the recommended needle gauge for administering a Mantoux tuberculin skin test?

Accepted Answer

26–27 gauge

Answer

A short, 26–27 gauge needle with a short bevel is recommended to ensure proper intradermal injection.

Question 5

After correctly placing a TST, the nurse observes no bleb (wheal) at the injection site. What action is most appropriate?

Accepted Answer

Repeat the test immediately at a site at least 2 inches from the first

Answer

If no bleb forms, the injection was likely subcutaneous rather than intradermal, and the test must be repeated at a different site.

(TB Test) Tuberculosis Test Certification Practice Test

(TB Test) Tuberculosis Test Certification Practice Test

TB Test Practice and Application 2