A nurse is assessing a client who received a Mantoux skin test 72 hours ago for tuberculosis screening. Which of the following findings indicates a positive test result?

Choice A reason: A blister-like area is not indicative of a positive Mantoux test, which shows induration; blisters suggest irritation. Assuming blisters are positive risks misdiagnosis, potentially missing tuberculosis exposure, critical to avoid in ensuring accurate screening and follow-up in clients tested for TB. Choice B reason: Ecchymosis (bruising) is not a positive Mantoux result; induration indicates exposure. Assuming ecchymosis is positive risks incorrect interpretation, potentially overlooking tuberculosis risk, critical to prevent in ensuring proper screening, diagnosis, and follow-up for clients undergoing TB skin testing. Choice C reason: A cool, blanched area suggests no reaction, not a positive Mantoux test, which requires induration. Assuming blanching is positive risks missing exposure, critical to avoid in ensuring accurate tuberculosis screening, guiding appropriate diagnostic follow-up, and protecting client and public health. Choice D reason: An elevated, hardened area (induration) at 72 hours indicates a positive Mantoux test, suggesting TB exposure, requiring further evaluation. This is critical for accurate screening, ensuring timely diagnosis, preventing disease spread, and guiding follow-up in clients tested for tuberculosis exposure.