The classic auscultatory finding in acute pericarditis is a high-pitched, scratchy pericardial _____.

The blank is **friction rub**. The lecture describes the pericardial friction rub as the classic finding in acute pericarditis and characterizes it as a high-pitched, scratchy sound. Its presence supports pericardial inflammation, although its absence does not by itself exclude the diagnosis. In larger effusions, muffled heart sounds may be more prominent, so examination findings can vary with the amount of fluid. **Key takeaway:** A scratchy pericardial friction rub is the classic auscultatory sign of acute pericarditis. **Glossary:** **Auscultatory**: detected by listening, usually with a stethoscope. **Muffled heart sounds**: heart sounds that are less distinct than usual.