Acute appendicitis

Inflammation of the appendix normally leads to severe pain in the lower right abdomen. In order to avoid complications such as a ruptured appendix, the inflamed part of the appendix is usually surgically removed.

At a glance

  • Typical signs of acute appendicitis are pain in the lower right abdomen, nausea, vomiting and fever. 
  • Appendicitis is when an appendage of the cecum (the first part of the large intestine) becomes inflamed. This appendage is usually called the appendix, but may also be referred to as the cecal appendage, vermiform appendix or vermiform process.
  • The most common and most effective treatment is for the appendix to be surgically removed.
  • Without treatment, the appendix could rupture, i.e., break or tear. A rupture can lead to life-threatening peritonitis, i.e., inflammation of the lining of the abdomen. 

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

Appendicitis: man standing in his living room holding his belly. He looks tense and appears to be in pain.

What is appendicitis?

With acute appendicitis, the appendix – a small pouch attached to the cecum (first section of the large intestine) – becomes inflamed. If the appendix wall becomes inflamed, this causes severe pain in the lower right abdomen. 

The inflammation can result in the formation of pus. Without treatment, a hole in the intestinal wall can also develop, meaning that the inflammation can spread to the entire abdomen. Such a rupture of the appendix is life-threatening. This is why most cases of acute appendicitis are quickly treated with surgery.

What happens during appendicitis?

The video below explains what happens during appendicitis. What are the symptoms and how can it be treated?

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What are the symptoms of appendicitis?

Appendicitis usually starts with pain around the belly button.

This is later followed by other symptoms such as:

  • severe pain, typically in the lower right abdomen
  • tense abdominal wall 
  • loss of appetite
  • nausea and vomiting
  • fever (develops later)
The characteristic symptoms of appendicitis are severe abdominal pain, abdominal swelling, loss of appetite, nausea and vomiting, fever.

With some people, the symptoms are not as typical or are only mild in nature. The inflammation can also manifest itself through the following signs:

  • upset stomach
  • digestive problems 
  • bloating 
  • diarrhea 
  • general feeling of being unwell

Not everybody’s appendix is in the same place. Sometimes it is located more towards the person’s back but it may also protrude further into the pelvis. As a result, non-typical abdominal pain or discomfort when urinating may also occur.

Occasionally, an irritated appendix may resolve on its own. In 90 percent of cases, however, the inflammation in the appendix progresses. The longer the symptoms last, the higher the risk of a ruptured appendix. Suspected appendicitis should therefore be assessed by a doctor without delay.

Important: If the fever rises, it can indicate a ruptured appendix. A rupture is a life-threatening complication that must be treated in hospital immediately.

What causes appendicitis?

The appendix is a small protuberance of the cecum that has a narrow lumen (opening). If this lumen is blocked, the appendix swells, interrupting the blood flow. The cells in the wall of the appendix die off. An inflammation develops, encouraged by bacteria from the intestine. 

The often pus-filled inflammation attacks the wall of the appendix, leading to a hole developing. This is known as a ruptured (or perforated) appendix. If the inflammation spreads to the entire abdomen, it can be life-threatening. A ruptured appendix affecting the abdomen sometimes becomes walled off, creating a pus-filled cavity known as an abscess.

What causes a blocked appendix?

There are lots of defense cells in the wall of the appendix, especially in young people. If this local immune system is activated by an infection, for example, the mucous membrane swells up and the narrow lumen of the appendix closes up.

With older people, the immune system in the appendix gradually becomes less efficient. As a result, there are usually other reasons for the appendix becoming blocked – for example, hardened fecal matter or changes to the intestinal wall. In rare cases, worms or tumors in the appendix can cause a blockage.

How common is appendicitis?

Acute appendicitis is one of the most common causes of severe abdominal pain and one of the most common reasons worldwide for emergency abdominal surgery. Appendicitis can occur at any age, but is especially likely between the ages of 10 and 19.

Around 2 out of 1,000 people develop acute appendicitis every year. The risk of men developing acute appendicitis once in their lifetime is just over 8 percent. For women, the risk is around 7 percent.

Important: A ruptured appendix occurs in up to one in five cases of acute appendicitis.

How does appendicitis develop?

Sometimes a grumbling appendix settles down on its own. However, the inflammation usually progresses in one of the following ways:

  • Uncomplicated appendicitis: inflammation of the appendix with no further complications. This form is the most common.
  • Ruptured appendix: a hole develops in the intestinal wall. This allows feces, bacteria and pus to escape and causes life-threatening peritonitis. Rising fever can indicate a ruptured appendix.
  • Formation of abscesses and phlegmons: a walled-off pus cavity (abscess) or pus-filled inflammation in the surrounding tissue may develop, depending on the location of the hole in the intestinal wall.

How is appendicitis diagnosed?

The doctor performs a physical examination to identify the first signs of appendicitis. This involves feeling the person’s abdomen.

Typical findings indicating acute appendicitis are:

  • tenderness when the doctor applies gentle pressure on the lower right abdomen
  • a hard, tense abdomen when the doctor feels it
  • pain in the lower right abdomen when moving the right leg or when pressure is suddenly released on the left side of the abdominal wall.

Many other abdominal and pelvic diseases cause abdominal pain similar to appendicitis – for example, inflammation of other parts of the intestine or diseases of the bladder or sex organs. As there are no physical signs that clearly indicate appendicitis, further examinations often follow:

  • a blood sample to measure inflammatory markers in the blood
  • an ultrasound to identify a thickened intestinal wall
  • a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan to identify appendicitis and rule out other conditions
  • in some cases, a diagnostic laparoscopy

How is appendicitis treated?

The most common and most effective treatment for acute appendicitis is surgery. This involves removing the infected appendix, with the surgeon either making an incision in the abdominal wall or performing minimally invasive (keyhole) surgery. A laparoscopy is performed using special endoscopes introduced into the abdominal cavity via several incisions.

The commonest and most effective treatment for appendicitis is surgery to remove the inflamed vermiform appendix.

If a pus-filled cavity (abscess) has already formed, the abscess is removed and any further fluid drained out through a small tube.

The precise timing of the surgery depends on whether any complications have already developed and whether circulation remains stable. It is normally recommended that surgeons wait no more than 12 hours after diagnosis to operate. An antibiotic is administered prior to the procedure to prevent any spread of infection. Pain-relieving medication can also be taken.

It may also be possible to treat uncomplicated appendicitis with antibiotics alone. This treatment does not always work, however. Within a year, the inflammation recurs in around 30 percent of people who have had the condition and surgery is then required. 

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen) (IQWiG). As at:

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