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What is appendicitis?

Appendix is a thin, tube or worm shaped structure that protrudes from the first portion of the large bowel (cecum) . The function of the appendix is unknown. In young people it contains a large number of lymphoid follicles (cluster of cells of the immune system involved in fighting infection and disease). This suggests that the function of the appendix is to do with the immune response to disease and infection. After adolescence, these follicles deteriorate . Appendicitis is where that appendix becomes inflamed.

The inflamed appendix can rapidly become infected. Appendicitis is almost always acute (sudden onset) and represents a surgical emergency since the inflamed appendix may burst (perforation) causing life threatening infection of the abdominal cavity (peritonitis)1,2.


Appendicitis is extremely common condition that affects approximately 250,000 people per year in the United States . Appendicitis is the most common cause of emergency abdominal surgery in infancy and childhood. It is more common in males than in females and occurs mostly in late teens and early twenties (peak 10-19 years of age). Appendicitis is generally uncommon in very young children and in the elderly2,3.

Cause of disease

In majority of patients with acute appendix (approximately 70%) there is obstruction of the lumen of the appendix (cavity within the appendix)2. This is most commonly due to calcified faeces (fecalith) although other causes include fibrous bands (scar tissue), tumours, parasites and foreign bodies , . Uncommonly, swelling of the lymphoid follicles in response to infection may be the cause of obstruction2. In approximately one third of patients, the lumen is not obstructed and only generalised inflammation is present2.

If not treated at this stage, the appendicitis progresses. The blood supply to the appendix is compromised by the bacterial infection in the wall of the appendix and by distension (stretching) of the lumen and wall of the appendix by pus or gas. This can lead to gangrene and perforation (rupture) of the appendix2, . The time period between appendicitis and gangrene and perforation is about 24 hrs although the time period varies considerably6.


There are also several complications of appendicitis. These include perforation, peritonitis, abscesses, pylephlebitis (infection of the deep veins of the body) and death6.

  1. Perforation is due to inflammation. Perforation occurs in approximately 50% of patients under 10 and over 50 before having surgery to remove the appendix (appendectomy)1,6.
  2. Peritonitis - This refers to infection of the abdominal cavity. Localised peritonitis indicates very small perforation of the appendix whereas spreading peritonitis indicates large-scale perforation of the appendix into the abdominal cavity. This is an emergency situation and in untreated patients can lead to death1,6
  3. Appendiceal abscess - An abscess is an infected area with pus that can cause swelling and destroy tissue. When perforation occurs, bacteria leaks out into the abdominal cavity and becomes walled off by adjacent organs forming these abscesses1,6.


Acute appendicitis can have a wide verity of presentations. It may be similar to almost any other acute abdominal condition and in turn acute appendicitis may be mimicked by a number of other conditions2, . The symptoms and signs of appendicitis often occur in a particular order and often is the only way a reliable diagnosis is made7.

Typically, the illness begins with a vague abdominal discomfort followed by slight feeling of nausea, loss of appetite and indigestion Initially the pain originates around the belly button or just below the breastbone. Here the pain is persis

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