For a patient with acute abdominal pain, which physical exam finding would suggest peritonitis?

Rebound tenderness is a classic physical exam finding that suggests peritonitis. This occurs when there is irritation of the lining of the abdominal cavity, which often happens due to infection, inflammation, or other significant conditions affecting the abdomen. When a clinician applies pressure to the abdomen and then suddenly releases it, a patient with peritonitis may experience increased pain upon release, known as rebound tenderness. This response indicates that the abdominal wall and underlying peritoneum are inflamed, which is a hallmark sign of peritonitis.

In contrast, normal bowel sounds would typically suggest that the intestines are functioning properly, while a palpable abdominal mass might indicate another issue, such as an obstruction or an organomegaly, but does not specifically point to peritonitis. Pain relief when supine could suggest a different condition, where certain positions alleviate discomfort, rather than indicating peritonitis, which usually causes consistent and pronounced pain regardless of position.