Which of the following is a sign of peritoneal irritation?

Rebound tenderness is a classic sign of peritoneal irritation, which occurs when the abdominal lining (peritoneum) becomes inflamed or irritated, often due to conditions such as appendicitis or peritonitis. This sign is assessed by gently pressing down on the abdomen and then quickly releasing the pressure. If there is pain upon release rather than application of pressure, this indicates irritation of the peritoneum. The presence of rebound tenderness suggests that the underlying tissues in the abdomen are inflamed, making it a significant finding in clinical assessment.

The other options—excessive urination, a regular heart rate, and clear lung sounds—do not indicate peritoneal irritation and are associated with different physiological conditions or variations. Excessive urination may suggest renal or metabolic issues, a regular heart rate points to stable cardiac function, and clear lung sounds generally indicate no respiratory distress or problems. None of these signs provide information about peritoneal inflammation or irritation.