Blumberg's sign is

Positive Blumberg's sign or rebound tenderness or Release sign is indicative of peritonitis which can occur in diseases like appendicitis, perforated peptic ulcer and may occur in ulcerative colitis with rebound tenderness in the right lower quadrant etc. Rebound tenderness on abdominal palpation is d/t the fact that the parietal peritoneum which has already been inflamed due to the presence of underlying inflamed organ also springs back along with the abdominal muscles. < p> Reference : page 458 A manual on clinical surgery Das 10th edition