The right forearm of a client who had a purified protein derivative (PPD) test for tuberculosis is reddened and raised about 3mm where the test was given. This PPD would be read as having which of the following results?
A. Indeterminate
B. Needs to be redone
C. Negative
D. Positive
Correct Answer: C. Negative
This test would be classed as negative. A 5 mm raised area would be a positive result if a client was HIV+ or had recent close contact with someone diagnosed with TB. If the patient is at a high risk of developing an active infection, a repeat test is recommended after an initial negative test to rule out the possibility of missing a case. However, a decision is made based on the risk factors.
Option A: Indeterminate isn’t a term used to describe results of a PPD test. It is a time-sensitive test. Tests that are read late are not accurate as they tend to under-estimate the size of the skin reaction. Therefore, the reliability of the test is compromised, and the results are doubtful.
Option B: To avoid this, repeat testing is recommended if the reaction is not read on time. The second test can be administered as soon as possible. However, if repeated, the test should preferably be performed within 7 days of the initial test to avoid boosting effect.
Option D: If the PPD is reddened and raised 10mm or more, it’s considered positive according to the CDC. If the infection risk is very high, the PPD test need not be repeated. The positive PPD test is usually followed by TB symptom assessment, physical exam, and chest radiograph.
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