How many times is a spirometry test typically performed to assess lung function?

• A. 4
• B. 1
• C. 3
• D. 2

Answer: (C)

Spirometry depends on getting consistent, repeatable results, because how hard and how long a person exhales can vary with effort and technique. Repeating the test with multiple, acceptable maneuvers lets the clinician confirm that the measurements are reliable. In practice, three acceptable efforts are performed to ensure reproducibility; the best two efforts should be close in value, which helps confirm the true lung function rather than a one-off result. If only one or two attempts were done, a misplaced effort or poor technique could skew the results. More attempts may be needed only if the initial efforts aren’t acceptable, but three is the typical number.