What and where is the appendix?

Appendicitis means inflammation of the appendix. The appendix is a small pouch that comes off the gut wall at the start of the large intestine. Appendicitis is common. Typical symptoms include tummy (abdominal) pain and being sick (vomiting). These symptoms gradually get worse over 6-24 hours. Some people have less typical symptoms. The usual treatment is an operation to remove the inflamed appendix, and the aim is to do this before it bursts (perforates). A perforated appendix is a very serious condition.

What is appendicitis?

Appendicitis means inflammation of the appendix. The inflamed appendix becomes infected with germs (bacteria) from the intestine. The inflamed appendix gradually swells and fills with pus. Eventually, if not treated, the swollen appendix might burst (perforate). This is very serious, as the contents of the intestine then leak into the tummy (abdominal) cavity. This can cause a serious infection of the membrane that lines the abdomen (peritonitis), or a collection of pus (an abscess) in the abdomen. So, if appendicitis is suspected, early treatment is best before it bursts.

Who gets appendicitis?

Appendicitis is common and can affect anyone of any age. Teenagers and young adults are the most commonly affected. About 6 in 100 people in the UK have appendicitis at some time in their lives. Appendicitis is the cause of the most common tummy (abdominal) surgical emergency admission to hospital in the UK. It is slightly more common in men than in women. It is much more common in western countries. This is thought to be partly due to the western diet which is often low in fibre.

Symptoms of appendicitis include:

  • Abdominal pain, usually starting just above the belly button and then moving to the right lower side of the abdomen
  • Nausea
  • Vomiting
  • Abdominal swelling
  • Pain when the right side of the abdomen is touched
  • Low-grade fever
  • Inability to pass gas
  • Change in normal bowel pattern


The standard treatment is to remove the appendix. The surgery, called an appendectomy, should be done as soon as possible to reduce the risk of the appendix rupturing.