rale

Rale is a medical term historically used to describe an abnormal lung sound heard with a stethoscope during auscultation. In modern practice, clinicians prefer the term crackle; rale is often considered outdated.

Rales are categorized as fine crackles and coarse crackles. Fine crackles are high-pitched and brief, usually heard in late inspiration, and are associated with interstitial processes such as pulmonary edema or fibrosis. Coarse crackles are lower in pitch, longer in duration, heard earlier in inspiration, and may reflect secretions or airways collapse, as seen in pneumonia or bronchitis.

They indicate involvement of small airways or alveolar spaces but are not diagnostic. Evaluation combines history, physical exam, imaging (chest X-ray or CT), and sometimes laboratory tests to establish a cause such as heart failure, infection, or interstitial lung disease. Rales may change with coughing depending on cause.

Because the term can be ambiguous and overlap with rhonchi or wheezes, crackles is the preferred term in contemporary medical literature. The term rale persists in older texts and in some clinical settings.