CAVIT Direct Care Worker Fundamentals Practice Exam

Which of the following indicates a positive result in a TB skin test?

1. Induration more than 10mm

2. Redness without swelling

3. Swelling without pain

4. Any reaction within 48 hours

The correct answer is: Induration more than 10mm

A positive result in a tuberculosis (TB) skin test, also known as the Mantoux test, is indicated by the presence of induration, which is a hard, raised area at the injection site. For individuals considered to be at risk, an induration measuring more than 10 mm is interpreted as a positive reaction. This measurement indicates that the body's immune system has reacted to the proteins injected during the test, suggesting that the person may have been exposed to the TB bacteria. While other reactions to the skin test can occur, such as redness or swelling, they do not hold the same significance in determining a positive result. Specifically, redness without swelling does not indicate a positive response, as the induration must be present for a valid interpretation. Similarly, swelling without pain or any reaction noted within the first 48 hours is not definitive for a positive test; what matters is the measurement of the induration specifically after the prescribed time frame. The focus on induration over a specific measurement helps healthcare providers accurately assess the likelihood of TB infection, guiding further testing or treatment as necessary, depending on a person’s risk factors and medical history.