Rebound tenderness is elicited by palpating slowly and deeply over a viscus and then suddenly releasing the palpating hand. If rebound tenderness is positive then the patient experiences pain. The sign is explained by the fact that gradual stretching of the abdominal wall by deep palpation followed by sudden release of this pressure stimulates the parietal peritoneum which, if inflamed, produces pain. Rebound tenderness is not always a reliable sign and should be interpreted with caution, particularly in those patients with a low pain threshold.
Rebound tenderness is commonly done as part of physical examination of a patient of appendicitis. Rebound tenderness is also named positive Blumberg’s sign.
While reading about appendicitis on wikipedia.com i found out that the definition of Blumberg’s sign is given wrong over there. According to wikipedia (on 7th May, 2010) Blumberg’s sign due to inflammed vermiform appendix is:
Palpation of the left iliac fossa, followed by sudden release causes contralateral (right iliac fossa) rebound tenderness.
Which is obviously not so. It is even technically incorrect as rebound phenomenon occurs on the ipsilateral side and not the contralateral.I have submitted the correction in the wikipedia article regarding Blumberg’s sign mistake. Hopefully they will approve it.
The positive blumberg’s sign or rebound tenderness is indicative of peritonitis (inflammation of peritoneum). Which means that blumberg sign can be positive for any disease condition inside the abdominal cavity which leads to peritonitis such as appendicitis (inflammation of appendix). In appendicitis the blumber’s sign or rebound tenderness will be positive in right iliac fossa of the patient (and on the left in case of citus inversus).