What is a hallmark sign of peritonitis?

A hallmark sign of peritonitis is a rigid board-like abdomen. This symptom occurs due to inflammation of the peritoneum, which causes the abdominal muscles to contract involuntarily as a protective mechanism. As a result, the abdomen becomes tense and firm, resembling a rigid board. This sign is significant because it indicates irritation or inflammation in the abdominal cavity, which can be due to various underlying conditions, such as infection from appendicitis or perforation of the bowel. Recognizing this sign is crucial for diagnosis and timely intervention in patients suspected of having peritonitis.