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Appendicitis is inflammation of the appendix, a small pouch on the gut wall at the start of the large intestine. It is a medical emergency as, left untreated, the appendix can burst or perforate.

What is the appendix?

The appendix is a small, blind-ended tube that comes off the caecum, which is the very first part of the large bowel (large intestine). In the vast majority of people the appendix is located in the bottom, right-hand quarter of the tummy.

The appendix is normally about 5-10 cm long, but quite narrow. It has muscular walls, like the intestine, and there is some immune tissue in those walls. Scientists used to believe that the appendix had no useful role in modern humans. They thought that our ancestors had needed the appendix only to digest tough food like tree bark. However, more recently it has been suggested that the appendix may contains a reservoir of helpful digestive bacteria and that, in early childhood, the immune tissues in the appendix are important in the development of the immune system. Despite all this it seems that removing the appendix leaves no ill effects.

What does it feel like?

Diagram of the bowel showing an inflamed appendix

Appendicitis is painful, although the severity of the pain can vary. The inflamed appendix becomes infected with germs (bacteria) from the intestine. Once it becomes inflamed, the appendix gradually swells and fills with pus. Eventually, if not treated, the swollen appendix becomes weakened, and can burst (perforate). This is very serious, as the contents of the intestine can then leak into the tummy (abdominal) cavity. Here they may cause a serious infection of the membrane that lines the abdomen (a condition called peritonitis), or a collection of pus (an abscess) in the abdomen. So, if appendicitis is suspected, early treatment is needed before it bursts.

The main symptom of appendicitis, at first, is tummy pain, which may start in the centre of the abdomen around the belly button, and which gets worse over a period of hours.

Read more about the symptoms of appendicitis.

What causes appendicitis?

Appendicitis is thought most often to be caused by blockage of the appendix 'tube' either by something stuck on the inside, or by swelling of the appendix wall. Blockage may be by trapped seeds, indigestible food remnants or hard stools (faeces) that get stuck in the appendix, or by lymph glands in the appendix wall which have swollen in response to infection elsewhere in the body.

If the appendix is inflamed and swollen, and cannot empty, then germs (bacteria) may thrive and cause inflammation in the wall and behind the blockage in the 'dead end' of the appendix.

Who gets it?

Appendicitis is common and can affect anyone of any age. Teenagers and young adults are the most commonly affected. About 1 in every 7 people in the UK have appendicitis at some time in their lives. Appendicitis can develop at any age but it is most common between 10 and 20 years of age. It is very rare under the age of 2 years.

It is slightly more common in women than in men and is much more common in western countries. This is thought to be partly due to the western diet which is often low in fibre. It is rare in rural parts of the developing world.

What are the symptoms of appendicitis?

The symptoms vary but the classic symptom is a dull pain around your belly button that then moves to become a much sharper severe pain in the right side of your lower tummy. Other symptoms may include nausea, vomiting, loss of appetite, diarrhoea and fever.

Over the next few hours the pain typically gets worse, and travels to the lower right-hand side of the abdomen. This is the area covering the normal position of the appendix.

Typically the pain becomes worse and worse over 6-24 hours. It may become severe. The pain tends to be sharper if you cough or make any jarring movements. The pain may ease a bit if you pull your knees up towards your chest, and may be worse if you push on your tummy or try to move around. The lower abdomen is usually tender, particularly in the lower right-hand side. You may find that pushing in on this area of your tummy gently with two fingers is very painful. Letting go - releasing the two fingers quickly after you push in - is often even more painful (this is called 'rebound tenderness').

Other symptoms that may occur include the following:

  • Feeling sick (nausea) and being off food are typical. You may be sick (vomit).
  • High temperature (fever) and generally feeling unwell.
  • Constipation may occur, and sometimes diarrhoea.
  • Frequent passing of urine may develop. This is thought to be due to the inflammation irritating the nearby ureter. The ureter is the tube between the kidney and bladder.

If your appendix bursts (perforates) then severe pain can spread to the entire abdomen. Any movement is painful and you will want to keep very still. Infected material from the appendix, together with contents of the bowel, can leak into your abdomen and track between the other organs. You become very ill as you develop serious infection of the membrane called the peritoneum, which lines the whole abdomen. This condition is called peritonitis.

If you develop peritonitis, coughing and moving the legs at the hips is painful. Your tummy will feel hard and tense and you won't be able to push into it at all. You may be unable to pass wind or go to the toilet, and probably won't want to.

Sometimes, when the appendix bursts, the infection is 'walled off' quickly by the membrane lining the stomach, which sticks to the appendix and traps the leaking fluid and pus. If this occurs you will still be in severe pain but the pain may remain quite focused in the lower right area of your abdomen, where a health professional may be able to feel the whole inflamed section of tissue as a firm, painful lump called an 'appendix mass'.

What is non-typical appendicitis like?

Not all cases of appendicitis have typical symptoms.

  • In some cases the pain may develop more slowly and run a more gradually smouldering course. This is particularly true when an appendix mass develops.
  • The pain can also start in the lower right-hand side of the tummy (abdomen), rather than around the belly button.
  • In some cases the pain may be relatively mild and may not actually become severe until the appendix perforates.
  • The site of the pain may also not be typical if the appendix lies in an unusual place. Sometimes it is felt around the back passage, for example, or lower down in the groin.
  • Appendicitis in pregnancy can begin quite vaguely further up the tummy or even under the ribs, as the appendix is pushed away from its usual location by the growing baby.
  • Appendicitis is rare in small babies, but if it does occur it can often look more like an attack of gastroenteritis, with being sick (vomiting), irritability and diarrhoea.
  • In some cases the appendix is not in the usual place. The pain of appendicitis can develop more slowly and in a different area such as in the hip joint or around the back passage. However, other symptoms, such as feeling sick (nausea) and high temperature (fever) are also seen.

How is appendicitis diagnosed?

A doctor may diagnose appendicitis quite easily if you have the typical symptoms. However, not everyone has typical symptoms. Sometimes it is difficult for doctors to be sure that appendicitis is the cause of the symptoms.

There is no easy, foolproof test that can confirm appendicitis. A surgeon often has to make the final judgement about whether to operate, based on their assessment of you. It therefore depends on whether your symptoms, and the findings when you are examined, suggest that appendicitis is the probable diagnosis.

Your tummy (abdomen) will be examined to assess where you are tender. This includes pushing into the tender areas to see if your muscles can relax, and where you are most tender. Blood tests may also help diagnosis. Urine testing is done to rule out urine infection, and women are usually offered pregnancy tests. Trials of a urine test looking for a protein called LRG are also continuing, which may help in diagnosis. Levels of LRG are very raised in the urine in appendicitis. However, this test is not yet widely available.

Imaging tests are often used to help decide on the diagnosis, if it is not clear. For example, an ultrasound scan or a CT scan may help to clarify the cause of the symptoms. If the diagnosis seems obvious or there is concern that your appendix has, or is about to, burst (perforate), you are likely to go straight to surgery. This will avoid the delay caused by taking you for a scan first.

Sometimes a surgeon advises to wait and see for a few hours or so while you are being monitored in hospital. This allows some time to see if your symptoms progress to a more definite diagnosis, or even if they change or go away. Antibiotic medicine will usually be given in this time.

What other problems might it be?

Some people develop pain that is similar to appendicitis but which is caused by other conditions. For example:

  • Pelvic inflammatory disease.
  • Urinary tract infection (cystitis).
  • Passing a kidney stone (ureteric colic)
  • Inflammation of the large bowel (large intestine) - a condition called colitis.
  • Inflammation of the first part of the large bowel (the caecum) itself - sometimes seen in Crohn's disease.
  • In women the right ovary lies near to the appendix, so pain in this area could come from either organ. A leaking ovarian cyst, or the normal pain of ovulation (sometimes called Mittelschmerz) can mimic appendicitis.
  • Ectopic pregnancy (when a pregnancy starts to develop outside the womb, usually in one of the Fallopian tubes) can mimic appendicitis.
  • In children swollen glands in the tummy around the bowel (mesenteric adenitis), often associated with viral infections can mimic appendicitis.
  • Occasionally pain from gallstones or from inflammation of the gallbladder (cholecystitis) can mimic appendicitis.

Some people have surgery only to find that the appendix is normal and not inflamed.

What is the treatment for appendicitis?

You will be admitted to hospital if appendicitis is suspected.

The normal, established treatment of appendicitis is an operation to remove the inflamed appendix. The aim is to do this before it bursts (perforates), as a perforated appendix is a very serious condition. Antibiotics are sometimes used to delay surgery. Very recently it has been suggested that in carefully selected cases appendicitis might possibly be treated by antibiotics rather than with surgery.

Surgery for appendicitis

The inflamed appendix is found and cut off at the first part of the large bowel (large intestine) - the caecum. The hole this leaves in the caecum is stitched up to stop contents from the gut leaking out. Antibiotic medicine is given before surgery to reduce the risk of infection developing at the site of the operation.

Sometimes antibiotics are used to delay surgery until the appendicitis has calmed a little. This may make the surgery safer and reduces the risk that the appendix will burst at operation.

Removal of the appendix is one of the most commonly performed operations in the UK. This is usually a straightforward and successful operation needing just a short recovery. Surgery is commonly done by a keyhole operation, as the recovery is quicker compared to having an open operation. The keyhole operation is performed through three tiny cuts, the largest of which is only around 1.5 cm in size.

Sometimes keyhole surgery isn't recommended and open surgery on the tummy (abdomen) area is performed instead. This is likely to be needed if the appendix has already burst and caused a severe abdominal infection (peritonitis) or formed a lump called an appendix mass. It is also more likely if:

  • You have had other abdominal surgery and have scarring.
  • During the keyhole surgery a blood vessel is damaged by the instruments and needs repair.
  • Your appendix is not situated in the usual place.
  • You are pregnant.

There are usually no long-term complications after the operation. As with any operation, there is a small risk of complications from the operation itself and from the anaesthetic. However, if you don't have an operation, an inflamed appendix is likely to burst and cause peritonitis. This can be life-threatening. Untreated burst appendix with peritonitis has caused many deaths in history. The famous magician, Harry Houdini, used to invite members of the audience to punch him in the stomach to demonstrate his strong abdominal muscles. Unfortunately, someone did this when he was unprepared. Even more unhappily, he had appendicitis at the time. His appendix burst and this resulted in his death some hours later.

Treatment of an appendix mass

If an appendix mass has formed then surgeons sometimes suggest postponing surgery whilst they drain the mass and treat with antibiotics, before doing a full appendicectomy a few weeks later. This allows patients to have surgery when they are less unwell, and the surgery is less difficult, as the inflammation has started to settle.

How about antibiotics instead of surgery for appendicitis?

Studies have suggested that in some cases appendicitis can be treated with antibiotics alone, without the need for surgery. This removes the risks associated with surgery, and is successful in many simple cases. However, the appendicitis often returns (relapses) later, so this is not yet established or routine practice.

Further reading & references

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other healthcare professional for diagnosis and treatment of medical conditions. For details see our conditions.

Dr Mary Lowth
Peer Reviewer:
Dr Adrian Bonsall
Document ID:
4564 (v44)
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