What are crackles or rales?

• A. Harsh crowing adventitious breath sounds caused by obstruction.
• B. Adventitious breath sounds that indicate fluid in the airways.
• C. Snoring-like adventitious breath sounds due to mucus.
• D. High-pitched whistling.

Answer: (B)

Crackles, or rales, are brief, discontinuous popping sounds heard on inspiration. They occur when small airways or alveoli that have been collapsed or filled with fluid suddenly reopen as air moves through them, so they reflect the presence of fluid in the lungs. This is commonly seen with conditions like pulmonary edema, pneumonia, or atelectasis. You can contrast them with other adventitious sounds: stridor is a harsh crowing sound from upper airway obstruction, rhonchi are snoring-like noises from mucus in larger airways, and wheezes are high-pitched whistling from narrowed airways. So crackles best fit the description of adventitious breath sounds indicating fluid in the airways.