Final answer:
Rebound tenderness, diminished bowel sounds, and a rigid, boardlike abdomen are assessment findings that indicate the possible onset of peritonitis.
Step-by-step explanation:
Peritonitis is an inflammation of the peritoneum, the lining of the abdomen. It can occur due to a bowel obstruction or from bacterial infections in conditions such as appendicitis or diverticulitis. Assessment findings that indicate the possible onset of peritonitis include rebound tenderness, diminished bowel sounds, and a rigid, boardlike abdomen. Diarrhea and bradycardia are not typically associated with peritonitis.