Rovsing's sign is positive when palpation of the left lower quadrant causes pain in the right lower quadrant, indicating irritation of the parietal peritoneum. This sign is most specific for appendiceal inflammation due to the anatomical location of the inflamed appendix in the right iliac fossa. The transmitted pressure across the peritoneal cavity from the left side elicits pain where the appendix is inflamed, helping to differentiate appendicitis from other causes of abdominal pain. It is therefore a useful clinical tool in diagnosing acute appendicitis in the surgical setting.

Reference: Bailey & Love’s Short Practice of Surgery, 27th Edition.