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What is appendicitis?

Appendicitis is a painful inflammation or swelling of the appendix, a 5-10 cm tube of tissue connected to the large intestine.

Appendicitis is a medical emergency and a person should be taken to A&E as soon as possible by car or by ambulance.

The appendix doesn’t seem to do anything useful, and the treatment for appendicitis is an operation to remove the appendix, as the body can live without it.

Around 1 in 13 people in the UK will get appendicitis at some point in their lives. It is more common in men than it is in women, usually occurring between the ages of 10 and 20.

Left untreated, an inflamed appendix can burst or perforate, spilling infectious materials into the abdominal cavity. This can lead to peritonitis, a serious inflammation of the abdominal cavity's lining (the peritoneum) that can be fatal unless it is treated quickly with antibiotics.


Sometimes a pus-filled abscess (an infection closed off from the rest of the body) forms outside the inflamed appendix. Scar tissue then "walls off" the appendix from the rest of the abdomen, preventing infection from spreading. 

An abscess may be detected on an ultrasound examination or CT scan. If symptoms settle, this may make it possible to delay or avoid surgery.

What causes appendicitis?

Appendicitis occurs when the appendix becomes blocked, often by a stool, a foreign body, or cancer. The blockage may also be due to an infection, since the appendix swells up in response to any infection in the body.

What are the symptoms of appendicitis?

The classic symptoms of appendicitis include:

  • Dull pain near the navel or the upper abdomen that becomes sharp as it moves to the lower right abdomen. This is usually the first sign.
  • Loss of appetite.
  • Nausea or vomiting soon after the abdominal pain begins.
  • Abdominal swelling.
  • A raised temperature.
  • Inability to pass wind.

In around 50% of cases there are other symptoms, including:

Seek medical attention if:

  • You have pain that matches these symptoms.
  • If you have any of the above symptoms, seek medical attention immediately as timely diagnosis and treatment are very important.

How is appendicitis diagnosed?

Diagnosing appendicitis can be tricky. The symptoms are often vague or extremely similar to other ailments, including gall bladder problems, bladder or urinary tract infections, Crohn's disease, gastritis, intestinal infection and ovary problems.

The following tests are usually used to make the diagnosis:

  • An abdominal examination to detect inflammation.
  • A urine test to rule out a urinary tract infection.
  • A rectal examination.
  • A blood test to see if your body is fighting infection.
  • CT (computerised tomography) scans and ultrasound.

WebMD Medical Reference

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