What Is Purulent Sputum?

Purulent sputum is off-white, yellow or green, and opaque. It indicates the presence of large numbers of white blood cells, especially neutrophilic granulocytes. In asthmatics, the sputum may look purulent from the eosinophilic cells. Red coloration, uniform or streaky, is usually due to its mixture with blood.

What causes purulent sputum?

Purulent sputum contains pus, composed of white blood cells, cellular debris, dead tissue, serous fluid, and viscous liquid (mucus). Purulent sputum is typically yellow or green. It is seen in cases of bronchiectasis, lung abscess, or an advanced stage of bronchitis.

What color sputum indicates infection?

If you see green or yellow phlegm, it's usually a sign that your body is fighting an infection. The color comes from white blood cells. At first, you may notice yellow phlegm that then progresses into green phlegm.