Sputum examination is the major screening tool for pulmonary tuberculosis. False negatives indicate a limitation in which test characteristic?

• A. Effectiveness
• B. Efficacy
• C. Specificity
• D. Sensitivity

Answer: (D)

The key measure here is sensitivity—the test’s ability to correctly identify people who have the disease. In screening, high sensitivity means few false negatives, so most true cases are detected. When sputum examination yields false negatives, it shows a limitation in sensitivity because some individuals with pulmonary tuberculosis are not identified by the test.

Specificity, by contrast, relates to correctly ruling out those without the disease, so false positives would indicate low specificity. Effectiveness and efficacy are not characteristics of a diagnostic test’s accuracy; they refer to how well an intervention works in real-world use or under ideal conditions, not to a test’s ability to detect disease. Thus, false negatives point to limited sensitivity.