Appendicitis is inflammation of the appendix.

The appendix is a small, finger-shaped tube projecting from the large intestine near the point where it joins the small intestine. The appendix may have some immune function, but it isn't an essential organ.

Except for trapped hernias, appendicitis is the most common cause of sudden, severe abdominal pain and abdominal surgery in the United States. Appendicitis is most common between the ages of 10 and 30.

The cause of appendicitis isn't fully understood. In most cases, a blockage inside the appendix probably starts a process in which the appendix becomes inflamed and infected. If inflamrmation continues without treatment, the appendix can rupture. A ruptured appendix spills bacteria-laden intestinal contents into the abdomen, causing peritonitis, which may result in a life-threatening infection. A rupture also may cause an abscess to form. In a woman, the ovaries and fallopian tubes may become infected, and the resulting blockage of the tubes may cause infertility. A ruptured appendix also may allow bacteria to infect the bloodstream-a life-threatening condition called septicemia.

Symptoms

Less than half of the people with appendicitis have the combination of characteristic symptoms: nauses, vomiting, and excruciating pain in the lower right abdomen. Pain may begin suddenly in the upper abdomen or around the navel; then nausea and vomiting develop. After a few hours, the nausea passes, and the pain shifts to the right lower portion of the abdomen. When a doctor presses on thìs area, it's tender, and when the pressure is released, the pain may increase sharply-a symptom called rebound tenderness. A fever of 100° to 101° F. is common.

Pain, particularly in infants and children, may be general rather than confined to the right lower portion of the abdomen. In older people and in pregnant women, the pain is usually less severe, and the ares is less tender.

If the appendix is ruptured, pain and fever may become severe. Worsening infection can lead to shock.

Diagnosis and Treatment

A blood test shows a moderate increase in the white blood cell count in response to the infection. Usually, in the early stages of appendicitis, most tests-- including X-rays, ultrasound scanning, and computed tomography (CT) --are essentially useless.

Typically, a doctor bases the diagnosis on the physical examination findings. To avoid a rupture of the appendix, abscess fornation, or inflammation of the lining of the abdominal cavity (peritonitis), a doctor perforns surgery immediately.

In nearly 15 percent of the operations for appendicitis, the appendix is found to be normal. However, delaying surgery until a doctor is certain of the cause of the abdominal pain can be fatal: An infected appendix can rupture less than 24 hours after symptoms begin. Even when appendicitis isn't the cause, the appendix is usually removed. Then the surgeon examines the abdomen and tries to determine the true cause of the pain.

With an early operation, the chance of death from appendicitis is very low. The person can usually leave the hospital in 2 or 3 days, and convalescence is normally quick and complete.

For a ruptured appendix, the prognosis is more serious. Fifty years ago, a rupture often was fatal. Antibiotics have lowered the death rate to nearly zero, but repeated operations and a long convalescence may be necessary.

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