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Appendicitis is an inflammation of the appendix. It is the most common acute surgical emergency situation involving the belly. The appendix is a small, tube-like structure in the lower right portion of the abdomen; it is attached to the first part of the colon (large intestine). Scientists have long struggled to figure out its function for some time, and the appendix is generally considered to be a vestigial structure, or one that no longer retains its original evolutionary function. Scientists recently proposed that the appendix serves as a reservoir for healthy bacteria.[1]

Henry Gray's illustration of the appendix, called here the vermiform process, in his 1918 Anatomy of the Human Body.

Appendicitis begins when the normally hollow inner part of the appendix becomes blocked, then slowly grows inflamed and infected. Once it starts, appendicitis is considered an emergency. With prompt treatment, usually surgery to remove the appendix, most patients recover. If treatment is delayed, however, the appendix can burst, causing infection and even death.

Acute appendicitis is treated by surgery to remove the appendix, in a procedure called appendectomy.



The most serious complication of appendicitis is rupture, which can lead to peritonitis (a dangerous infection that occurs as bacteria and other contents of the torn appendix leak into the abdomen) and abscess (a swollen mass filled with fluid and bacteria).

Other Names

  • Acute appendicitis
  • Appy (slang)
  • Epityphlitis

Types of Appendicitis

Appendicitis is generally classified into three types .

  • Acute appendicitis is the most common type. It develops over the course of a few days or less, can be easily diagnosed, and usually requires immediate surgery to remove the appendix.
  • Recurrent appendicitis is a type of appendicitis that is like acute appendicitis but gets better on its own, then recurs. This pattern is uncommon.[2]
  • Chronic appendicitis is a type of appendicitis that develops more slowly, has less pronounced symptoms, and is more difficult to diagnose. Chronic appendicitis does not always require surgery but may require ongoing treatment for chronic inflammation of the appendix. It is sometimes termed grumbling appendicitis, and accounts for 1%–2% of all cases of appendicitis.[3]


Appendicitis is caused when the the inside of the appendix (the lumen) becomes blocked. The blockage leads to increased pressure, decreased blood flow, and inflammation. If the blockage is not treated, gangrene and rupture (breaking or tearing) of the appendix can result.

The appendix, small intestine, and large intestine. Detail shows an inflamed appendix. Source: NIH

Most commonly, feces blocks the inside of the appendix. The appendix may also be squeezed and obstructed from the outside if infections in the intestine cause swelling of lymph nodes (known as lymphoid hyperplasia). Traumatic injury to the abdomen may lead to appendicitis in a small number of people; in very rare cases, appendicitis can be the first symptom of appendix cancer.

Heredity may also be a factor. For example, appendicitis that runs in families may result from the family members all having a certain type of appendix that is more easily obstructed.

Signs and Symptoms

Symptoms include pain in the abdomen, loss of appetite, nausea, vomiting, constipation or diarrhea, inability to pass gas, low-grade fever, and abdominal swelling. Not everyone has all of these symptoms, and it can be especially hard to diagnose the condition in very young children.

A more detailed list of symptoms follows:

  • Pain in the abdomen. It often starts first around the belly button, then moving to the lower right area.
  • loss of appetite
  • nausea
  • vomiting
  • constipation or diarrhea
  • inability to pass gas
  • low-grade fever and chills
  • abdominal swelling
  • elevated white blood cell count

The pain in the abdomen may be vague and mild at first, but it usually gets worse over time. The pain can also get worse with moving, taking deep breaths, coughing, or sneezing. People may have a sensation called "downward urge," also known as "tenesmus," or the feeling that a bowel movement will relieve their discomfort. It is extremely important that people with these symptoms do not take laxatives, enemas to relieve constipation, or highly potent pain medications in this situation, as these can mask other symptoms that the doctor should know about and even cause the appendix to rupture. Anyone with these symptoms needs to see a qualified physician immediately.

In cases of untreated appendicitis, the appendix can rupture, spilling pus and infective material into the abdomen and causing a serious condition called peritonitis. Peritonitis is an inflammation of the peritoneum which is a thin membrane that lines the abdominal wall and covers most of the organs of the body. Peritonitis resulting from a ruptured appendix may occur 36-72 hours after the onset of appendicitis. Symptoms of peritonitis include fever, severe abdominal pain, and tenderness that is worsened by movement and pressure on the abdomen. The abdomen may also become stiff and board-like. Other symptoms can include weakness, pale skin, and shock. The death rate from peritonitis is approximately 20%.

People with special conditions

Not everyone with appendicitis has all the symptoms. This is especially true for

  • people who use immunosuppressive therapy such as steroids
  • people who have received a transplanted organ
  • people infected with the HIV virus
  • people with diabetes
  • people who have [[cancer}cancer]] or who are receiving chemotherapy
  • obese people

These patients may experience a feeling of being "unwell," rather than the specific symptoms above.

Other groups whose symptoms might not be typical include pregnant women, the very young, and the very old.

  • Pregnant women: Abdominal pain, nausea, and vomiting are more common during pregnancy and may or may not be the signs of appendicitis. Many women who develop appendicitis during pregnancy do not experience the classic symptoms. Pregnant women who experience pain on the right side of the abdomen need to contact a doctor. Women in their third trimester are most at risk.
  • Infants and young children: Infants and young children cannot communicate their pain history to parents or doctors. Without a clear history, doctors must rely on a physical exam and less specific symptoms, such as vomiting and fatigue. Toddlers with appendicitis sometimes have trouble eating and may seem unusually sleepy. Children may have constipation, but may also have small stools that contain mucus. Symptoms vary widely among children, and children are more likely to have a ruptured appendix than adults are.
  • The elderly: Older patients tend to have more medical problems than young patients. The elderly often experience less fever and less severe abdominal pain than other patients do. Many older adults do not know that they have a serious problem until the appendix is close to rupturing. In an elderly person, a slight fever and abdominal pain on the right side are reasons to call or see a doctor right away.


McBurney's point (1) is sometimes where appendix pain settles. It is in the right lower abdomen, two-thirds of the way from the navel (2) to the tip of the hipbone (3). Source: Wikimedia Commons, by Steven Fruitsmaak, GNU FDL. A physical examination is the first step in the diagnosis of appendicitis. Any previous medical conditions and surgeries, family history, medications, and allergies are important information to the doctor. Before beginning a physical examination, a nurse or doctor will usually measure vital signs: temperature, pulse rate, breathing rate, and blood pressure. Usually the physical examination includes the whole body. Generalized symptoms such as fever, rash, or swelling of the lymph nodes may point to diseases that do not require surgery. Examination of the abdomen helps narrow down the diagnosis, especially if the location of the pain can be found. Doctors look especially for pain at what is called McBurney's point (see figure). Other valuable indicators of appendiceal inflammation are tenderness (pain when touched) and guarding (the tensing of abdominal muscles when touched). Psoas sign and obuturator sign are examination signs that are important to physicians, for the diagnosis of appendicitis.

The following is a list of some of the conditions that can cause abdominal pain similar to that of appendicitis:

In addition to a physical examination, a doctor may decide to do tests:

  • Blood tests: Blood tests are used to check for signs of infection, such as a high white blood cell count. Blood chemistries may also show dehydration or abnormalities in fluid balance. A urine test is used to rule out a urinary tract infection. In women of childbearing age, pregnancy must be considered, even in women using birth control. The doctor can check for pregnancy with a simple urine test.
  • Imaging tests: The most common test used to diagnose appendicitis is the CT (computed tomography) scan. This test provides a series of cross-sectional images of the body to help diagnosis. Because a CT scan produces radiation that could harm a developing fetus, women of childbearing age need to have a pregnancy test prior to the scan. Ultrasound may also show appendicitis, but emits no harmful radiation, so it is often the first-choice test in pregnant women, women of childbearing age, and children. However, ultrasound is not very sensitive, meaning that it does not pick up all cases, so a negative test result might still mean the appendix is inflamed.[4]

Sometimes x-rays are used, although they are far less helpful in diagnosing appendicitis than CT scans or even ultrasounds. They can occasionally show signs of obstruction, perforation (a hole in the appendix), foreign bodies, and in rare cases, an appendicolith (hardened stool) in the appendix.

In a great many cases, depending on the surgeon's evaluation, a patient may be taken to surgery without having had a CT scan or ultrasound. In these cases the diagnosis of appendicitis is quite likely, and delaying for a test might not be in the patient's best interests. In children a CT scan may be avoided to prevent exposure to radiation. The choice for CT scan or ultrasound exam is most commonly used in cases with less specific findings on physical examination.



Acute appendicitis is treated by surgery to remove the appendix. This surgical procedure is called appendectomy. An appendectomy is done under general anesthesia, meaning that the patient is asleep and cannot feel any pain during the operation. An appendectomy is usually performed either as an open surgery, through a single incision several inches long; or laparoscopically through several smaller incisions. The appendix is almost always removed, even if it is found to be normal. This is because if the patient ever has pain again in that area, future doctors will know it is not the appendix and can focus on looking for other causes. (However, in rare cases, the stump of a previously removed appendix can become infected.)

The general procedure for an appendectomy is as follows:

  1. The patient is given antibiotics immediately if there are signs of sepsis or an infection. Otherwise a single dose of prophylactic intravenous antibiotics is given immediately prior to surgery.
  2. The patient is given general anesthesia and prepped for surgery. The abdomen is prepared and draped and examined under anaesthesia.
  3. After the patient is anesthetized, the surgeon can remove the appendix either by the traditional open procedure (by making one 5-7 cm incision in the abdomen) or via laparoscopy (in which three or four 2.5 cm incisions are made in the abdomen).

Click here for a step-by-step illustration of an appendectomy.


If the diagnosis is uncertain, or if a doctor suspects that the patient's symptoms may have a non-surgical or medically treatable cause, antibiotics may be prescribed. Should the cause of the pain be an infection, symptoms should resolve with intravenous antibiotics and intravenous fluids. When an operating room is not available, such as at sea, intravenous antibiotics are also used to try to shrink the inflammation and infection present in the structures surrounding the appendix, and to delay or avoid the onset of sepsis. This approach is often used in the military.[5] In general, however, appendicitis cannot be treated with antibiotics alone and will sooner or later require surgery.


The most serious complication of appendicitis that is not diagnosed and treated quickly is rupture of the appendix. Infants, young children, and older adults are at highest risk for rupture. This is likely due to the delay in seeking medical advice after the onset of appendicitis symptoms. Thus, it is extremely important to call a doctor at the earliest signs of possible appendicitis.

A ruptured appendix can lead to peritonitis and abscess. Peritonitis is a dangerous infection that occurs as bacteria and other contents of the torn appendix leak into the abdomen. In people with appendicitis, an abscess usually takes the form of a swollen mass filled with fluid and bacteria, sometimes as large as a grapefruit. Regardless of its size, an abscess requires immediate treatment before it ruptures and possibly also causes peritonitis. In a few patients, complications of appendicitis can lead to organ failure and death.


There is no known way to prevent appendicitis. Some doctors think that high-fiber diets—those with plenty of fruits, vegetables|vegetables]], and whole grains—reduce the chances a person will develop appendicitis.


The appendix ruptures in 15% of appendicitis cases within 36 hours. Anyone can develop appendicitis, regardless of age or sex, but it occurs most often between the ages of 10 and 20[6] and there is a slightly higher incidence in men. One in six people will be diagnosed with appendicitis at some point in their life. In 2005, the Centers for Disease Control and Prevention reported 321,000 American cases of appendicitis. In England, the rate is about 40,000 hospital admissions per year.[6]

On average, 300 to 400 Americans die of appendicitis each year.


There are a number of clinical trials related to appendicitis and its treatment that are currently recruiting participants. For instance, a randomized trial at the University of Tennessee seeks to compare early and interval appendectomy, both commonly-used surgical treatments, for ruptured appendicitis in children. Another clinical trial at the University of California-San Diego is experimenting with single-incision laparoscopy for the treatment of appendicitis.

For a complete listing of American government-sponsored clinical trials, and for more information on who is eligible to participate, click here.


The appendix appeared in drawings done by Leonardo DaVinci at the end of the 15th century, and was formally described by the Italian anatomist Berengario DaCarpi in 1521.[7]

Inflammation of the appendix has long plagued humans. For example, an Egyptian mummy of the Byzantine era, discovered in the early 20th century, had adhesions in its lower abdomen that looked like appendicitis. However, the term "appendicitis" was not used until 1886 in the American Journal of Medical Science. [8] In that article, titled "Perforating inflammation of the vermiform appendix with special reference to its early diagnosis and treatment," American physician and Harvard Medical School pathologist Reginald H. Fitz outlined the symptoms of a diseased appendix and invented the term "appendicitis." Fitz's paper not only addressed the clinical features of appendicitis but also called for the surgical removal of the appendix at the first signs of inflammation,[7] which has since become standard of practice. Thanks to advances in modern surgery and improvements in diagnostic technologies, mortality rates of appendicitis and appendectomy have greatly declined.


  1. ↑ Randal Bollinger R, Barbas AS, Bush EL, Lin SS, Parker W. Biofilms in the large bowel suggest an apparent function of the human vermiform appendix. J Theor Biol. 2007 Dec 21;249(4):826-31. Epub 2007 Sep 7. Abstract
  2. ↑ Mattei P, Sola JE, Yeo CJ. Chronic and recurrent appendicitis are uncommon entities often misdiagnosed. J Am Coll Surg. 1994 Apr;178(4):385-9. Abstract
  3. ↑ Johnson TR, DeCosse JJ. Colonoscopic diagnosis of grumbling appendicitis. Lancet. 1998 Feb 14;351(9101):495. Abstract
  4. ↑ Williams R, Shaw J. Ultrasound scanning in the diagnosis of acute appendicitis in pregnancy. Emerg Med J. 2007 May;24(5):359-60. Reference | Summary
  5. ↑ Adams ML. The medical management of acute appendicitis in a nonsurgical environment: a retrospective case review. Mil Med. 1990 Aug;155(8):345-7. Abstract
  6. ↑ 6.0 6.1 Humes DJ, Simpson J. Acute appendicitis. BMJ. 2006 Sep 9;333(7567):530-4. Abstract | Full Text
  7. ↑ 7.0 7.1 Williams GR. Presidential Address: a history of appendicitis. With anecdotes illustrating its importance. Ann Surg. 1983 May;197(5):495-506. Abstract | Full Text
  8. ↑ Fitz, RH. Perforating inflammation of the vermiform appendix with special reference to its early diagnosis and treatment. American Journal of Medical Sciences. 1886; 92:321.
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