Appendicitis is an inflammation of the appendix, a small worm-like pouch attached to the large bowel. It can happen at any age but most cases are between 8-25 years of age. It is rarely seen in children aged under two years. For young people, appendicitis is probably the most common cause of stomach pain requiring emergency surgery. In most cases, the specific reason for the inflammation is not known but it is sometimes caused by small pieces of hardened stool that get stuck in the appendix. The symptoms can be extremely variable but often take the following classic pattern. The first sign is usually a pain or discomfort in the centre of the abdomen. This pain comes and goes in waves and is often thought at first to be a simple stomach upset.

After a few hours, the pain becomes more noticeable and constant in the lower right part of the stomach. It is increased by movement or coughing. The patient often loses their appetite, feels sick, and vomits. The temperature is raised and the complexion becomes flushed. The breath may smell offensive.

In many instances, like appendicitis, a careful clinical examination is as good as or better than expensive high-tech tests.
Six aspects of the history exam and the presence of at least four of seven physical symptoms provided the best method for diagnosing appendicitis without the aid of surgical methods. Observation of right lower-quadrant pain, rigidity of the lower abdominal muscle wall and migration of pain from the left side to the right side of the abdomen are the three most prominent clinical findings that indicate a high probability of appendicitis.

Other clinical signs and symptoms that were found to be useful in accurately diagnosing appendicitis included pain before vomiting, irritation of the psoas muscle (found in the lower abdomen), fever, rebound tenderness, guarding (voluntary contraction of the abdominal muscle), no history of similar pain, rectal tenderness, anorexia, nausea and vomiting.

There is no one test that will diagnose appendicitis with certainty. Surgery is performed on the basis of the doctor's examination and results of the tests. Many diseases can cause the same symptoms as appendicitis which is why surgeons find a normal appendix in 3 out of 10 operations.

Surgical removal of the appendix (appendicectomy) is the recommended treatment and is usually performed under general anesthesia. In uncomplicated cases, a 2-3 day hospital stay is typical.

About one fifth of the patients who undergo surgery turn out to have a ruptured appendix. This increases the risk of peritonitis, a more wide spread and serious abdominal inflammation. Adhesions from postoperative scar tissue may develop and block or obstruct the bowel. Fortunately, this only happens in a small number of all patients. The condition usually occurs within three months of the operation.