Which exudate color is indicative of infection?

• A. Serous drainage
• B. Catarrhal drainage
• C. Sanguineous drainage
• D. Purulent drainage

Answer: (D)

Purulent drainage signals infection because pus is made up of bacteria, dead neutrophils, and cellular debris, giving it a thick, opaque appearance that is often yellow or green. This color and consistency reflect an active bacterial infection and the body’s immune response. Noninfectious inflammatory fluids tend to be serous (clear and watery) or sanguineous (blood-tinged), or simply mucus in catarrhal drainage. So the presence of purulent drainage is the hallmark of infection.