A sputum test analyzes a sample of the mucus or phlegm that you cough up to check for bacteria or other causes of congestion and chronic cough.
Ordinarily, the sputum sample comprises any mucus that you cough up. If you are unable to raise enough sputum, your physician may use a bronchoscope to collect a sample.
Sputum Induction (PDF)
This test helps your healthcare provider find out whether the buildup of phlegm in your lungs is caused by bacteria, fungi or another microorganism.