Written by Ada’s Medical Knowledge Team
What is acute appendicitis?
Acute appendicitis is an infection of the appendix – the 3 ½-inch-long pouch of tissue attached to the large intestine on the lower right side of the abdomen. This infection and the resulting inflammation can cause symptoms including:
- Loss of appetite
- An upset stomach
Acute appendicitis is a medical emergency because, if it is not treated, the appendix can burst, and infected material can spread into the abdominal cavity, the part of the body that contains important organs such as the liver, pancreas and intestines.. This is a life-threatening situation and must be treated urgently with antibiotics, as well as by removing the infected appendix.
An appendectomy (surgery to remove the appendix), also known as an appendicectomy, is the most common treatment for acute appendicitis. While the appendix may play a role in young children’s immune system, it serves no known purpose in adults and can be removed via an appendectomy without harmful consequences.
Acute appendicitis symptoms
The signs and symptoms of appendicitis appear quickly, usually starting with abdominal (stomach) pain.
As acute appendicitis can lead to a burst appendix within 24 to 72 hours, it is important to seek medical attention as soon as symptoms begin to appear.
- Pain in the upper abdomen or near the navel, starting dull and becoming sharper as it moves to the lower right-hand side. This location is most common, but pain can also occur in other parts of the abdomen. Often, movement worsens the pain.
- Loss of appetite
- Nausea and vomiting
Other common symptoms include:
- Fever and chills
- Constipation, diarrhea or alternating periods of both
Good to know: Symptoms of a burst appendix include intense abdominal pain in the lower right side that decreases and becomes generalized abdominal pain, accompanied by a high fever.
People experiencing possible symptoms of acute appendicitis can also use the free Ada app to carry out a symptom assessment. It is usually necessary to seek emergency care.
Acute appendicitis symptoms in children and adolescents
Children are most likely to get appendicitis between the ages of 8 and 16. Young children with acute appendicitis may have difficulty describing the symptoms they are experiencing, so it is important that parents are aware of the signs of appendicitis.
The most common symptoms of acute appendicitis in children are:
- Abdominal pain and pain with movement
- Loss of appetite
- Nausea and vomiting
Young children cannot always easily explain the specific location or feeling of pain. Even if a child is experiencing localized pain on the right side of their abdomen, they might identify the pain as affecting their entire stomach. This could lead parents to think their child has a different condition.
Children with appendicitis may also lie down and bend either the right hip or both hips upward as though drawing their knees to their chest. This position reduces the discomfort caused by an inflamed appendix. They may also be reluctant to breathe deeply, instead choosing to breathe shallowly into the chest to avoid moving the painful abdominal wall.
In older children and teenagers, the most common symptoms are similar to those experienced by adults.
Good to know: It is not uncommon for acute appendicitis in children to be confused with gastroenteritis, a common condition also known as stomach flu. A misdiagnosis can increase the risk of a burst appendix.
Acute appendicitis symptoms in pregnancy
Identifying appendicitis in pregnant people can be difficult, as many of the symptoms are similar to the discomfort normally associated with the early stages of pregnancy, such as:
If persistent nausea, vomiting and cramping occur, the affected person should seek urgent medical advice.
The uterus may also push the appendix into the upper abdomen by a few centimeters, particularly during the third trimester. In this case, pain from appendicitis may also occur in the upper right side of the abdomen, instead of just in the usual position in the lower right side.
People in the later stages of pregnancy are difficult to diagnose with appendicitis because they tend to have unusual symptoms. These can include:
- A sudden change in bowel habits (constipation or diarrhea)
- An increase in gas
- New or worsening heartburn
- Urinary symptoms such as frequent urination
Pregnant people experiencing possible symptoms of acute appendicitis can carry out a free symptom assessment in the Ada app.
Acute appendicitis causes
Appendicitis is generally caused by a blockage of the appendix, which increases the pressure inside the appendix and can cut off blood flow. Inside the blocked appendix, bacteria multiply and pus accumulates, which further damages the wall of the appendix and causes pain and irritation. If the inflammation is not relieved, part of the wall of the appendix may die, and a hole may form. This is known as a perforation or rupture, and if this happens, urgent medical help is needed.
- Infections caused by bacteria or, less commonly, viruses
- Hemolytic anemia
- Swollen lymph tissue in the area, more common among people with disorders that lead to inflammation in the bowel, such as diverticulitis, ulcerative colitis, or Crohn’s disease
- Tumors of the appendix, although these are rare
- Intestinal worms, although this is uncommon
- Foreign bodies, such as fruit seed residue, although this is very rare
Acute appendicitis vs. chronic appendicitis
The most common type of appendicitis is acute, in which an infection causes sharp pain that rapidly develops over a period of hours. However, in rare instances, appendicitis may develop slowly over a period of days or weeks. This is known as chronic, or recurrent, appendicitis.
The symptoms of chronic appendicitis tend to come and go and are usually less intense than those of acute appendicitis. The symptoms resemble those of acute appendicitis, but with pain that is usually dull and achy rather than sharp. Nausea and chills may accompany the pain.
Chronic appendicitis occurs when the inside of the appendix is partially obstructed and becomes infected, but the pressure building inside the infected, inflamed appendix dislodges the obstruction instead of causing rupture or perforation. Symptoms then subside until the appendix becomes blocked again.
As the symptoms of chronic appendicitis are similar to other chronic digestive issues, this condition is sometimes confused with:
To diagnose chronic appendicitis, the following diagnostic techniques can be used:
- Magnetic resonance imaging (MRI)
- Computed tomography (CT) scans
Acute appendicitis diagnosis
Acute appendicitis symptoms are similar to those of other conditions, such as:
- Urinary tract infection (UTI)](/conditions/urinary-tract-infection/)
- Bladder infection
- Crohn’s disease
- Gallbladder issues
- Intestinal infection
To make a clear diagnosis, doctors will typically use a range of tests.
Pain in the abdomen can have a number of causes. In addition to this, the exact position of the appendix within the abdomen differs slightly from person to person. For these reasons, it can sometimes be hard for both affected people and doctors to diagnose acute appendicitis.
Doctors examining a person with suspected acute appendicitis will take a verbal history of their symptoms and examine the affected person’s abdomen. Laboratory tests are sometimes used to help doctors confirm whether or not the affected person indeed has appendicitis, and can be used to help doctors decide if they should operate, but they cannot be used to confirm a diagnosis of appendicitis.
Tests used in the diagnosis of acute appendicitis include:
- Physical examination of the abdomen
- Rectal exam
- Blood tests for signs of infection, such as a white blood cell count
- CT scan
- MRI scan
- Abdominal ultrasonography
- Urine test, to exclude a UTI as the cause
Acute appendicitis risks and complications
The most serious risk is that acute appendicitis will cause the appendix to burst (perforate), causing infected material to collect and spread to other parts of the belly. The vast majority of cases of perforated appendix are successfully treated. If the infection spreads widely throughout the abdomen and is not treated urgently, it could result in death.
Good to know: A burst appendix is a medical emergency requiring immediate treatment and a hospital stay.
Perforation of the appendix
If the appendix becomes blocked, the fluid and mucus inside it cannot pass out. Instead they accumulate and increase the pressure inside the appendix. This leads to swelling and the bacteria inside the appendix to multiply.
This swelling constricts the appendix’s blood supply. If the blood supply does not come back and the swelling is not treated, cells in the appendix wall can die, causing a hole to open or the tissue to become porous. This is known as perforation or rupture of the appendix.
If this happens, bacteria can leak out of the appendix, and if any pus has accumulated, it too will leak out into the tissues surrounding the appendix. This can cause peritonitis. This process is typically very painful and is always a serious condition requiring emergency medical treatment. A perforated appendix can itself have several complications besides peritonitis, including abscesses, and gangrene.
Good to know: People who have a perforated appendix may experience a worsening of symptoms over time. Appendiceal perforations can vary in severity, but this is something that can only be determined by tests carried out by trained medical staff. It is not possible to gauge the severity of a ruptured appendix at home, and professional medical attention is needed.
Peritonitis is uncommon, but when it does occur, it is a medical emergency. Peritonitis is an infection of the peritoneum, the lining of the abdominal cavity, usually the result of an infection spreading from an organ to the peritoneum. The regions in which pain is felt and how severe the pain is, change as the infection spreads.
Generally, a perforated appendix will be painful, and as the infection spreads to the parts of the peritoneum nearest the appendix, the pain will also spread. If the infection then spreads to the entire peritoneum, the pain will then be felt as general belly pain and tenderness.
Pain from peritonitis feels worse when the affected person bends their hips or coughs; it is also painful if pressure is applied. In cases related to appendicitis, pain will usually be most intense over the appendix, where the infection began.
Other symptoms of peritonitis may include:
- Fever, a body temperature of 38 degrees C / 100.4 degrees F or higher.
- Diarrhea or reduced bowel movements (ileus)
- Low blood pressure
- Fast heartbeat
- Low output of urine
- Sepsis, in severe cases
Abscesses around the appendix
Appendiceal abscesses are the most common complication of a perforated appendix. An abscess is a collection of pus that forms in a tissue, space or organ in the body. People with appendiceal abscesses may experience abdominal pain and high fever, but because these are fairly common symptoms, a standard physical examination may not be enough to make the diagnosis. An abdominal ultrasound or CT scan is often needed to show for certain that an abscess has formed.
If the abscess is small, the affected person will be given intravenous antibiotics to try to reduce the size. Surgery to remove the appendix will only be performed some weeks later, with the affected person being closely monitored in the meantime. This is known as an interval appendectomy.
If the abscess is larger or has many different pockets of pus, it will be drained, and intravenous antibiotics will be administered. In the case of a large abscess that improves after drainage and antibiotics, a drainage catheter will be left in until the abscess is cleared, and surgery to remove the appendix will take place a few weeks later. In the case of a large, multicompartmental abscess, surgical drainage should be done quickly, and the appendix may be removed at the same time if this is safe for the affected person.
Good to know: Although it seems counterintuitive not to perform surgery as soon as possible if a complication such as an abscess has formed, it is in fact sometimes safer to delay operating. This is due to the very high risk of complications that might occur if surgery is performed on a very ill patient or around an abscess that might contaminate the abdominal cavity if it bursts. If you are concerned about the timing of your or a loved one’s surgery, speak to the surgeon and/or the care team involved.
Gangrenous perforated appendix
This rare complication occurs when a perforated appendix becomes gangrenous, which means that the tissue dies and begins to decompose. In such cases, sepsis and peritonitis may occur, and the affected person’s symptoms are usually severe. This disorder is a medical emergency.
In some cases, a very severely inflamed appendix may push the small intestine into a position where it becomes kinked. This blocks the passage of food through the intestines. People with an intestinal obstruction may have bright yellow or green vomit, and an X-ray or CT scan is needed for a conclusive diagnosis.
Acute appendicitis treatment
An appendectomy (surgery to remove the appendix), also known as an appendicectomy outside the US, is the chosen treatment method for acute appendicitis in almost all cases. This is because the risk of an infected appendix rupturing and causing a potentially dangerous infection is extremely high.
Recent evidence has suggested that some cases of uncomplicated appendicitis can be treated with antibiotics instead of an appendectomy. However, this is only appropriate when the appendix has not burst or caused an abscess, and studies have not yet shown that antibiotic-only treatment is as effective as an appendectomy, which remains the standard treatment for appendicitis.
Generally, someone who is known or strongly suspected to have acute appendicitis will be admitted to hospital. They will not be allowed to eat or drink, but will be given intravenous fluids and painkillers, and scheduled for surgery. Surgery generally takes place as soon as possible in order to prevent the infection spreading or complications occurring. In many cases, doctors will also administer antibiotics through a drip both before and after surgery.
Surgery for appendicitis
Surgery is the standard treatment for appendicitis regardless of whether or not complications have occurred. Procedures to remove the appendix, known as appendectomies, can be done using traditional open surgery or using less invasive laparoscopic techniques.
Laparoscopic surgery and open appendectomy take about the same amount of time. Surgery for a perforated or infected appendix may take longer than surgery for a minimally-affected appendix.
Complications are rare in surgery for acute appendicitis. Laparoscopic surgery has a lower chance of complications, though, as in all surgery, complications may occur.
Recovering from appendectomy
After surgery, people should avoid strenuous activity or heavy lifting for some weeks, and take special care to ensure that their wounds are kept clean and dry. Normal diet can usually be resumed fairly soon after surgery, often even before the affected person is discharged from hospital. However the recovery advice given may vary based on individual and surgical factors, so it is important to always follow the instructions given by one’s medical team. 
Often, additional medications to treat pain or restore normal bowel movements are prescribed by the attending physician.
Acute Appendicitis FAQs
Q: How can I tell if it’s appendicitis or something less serious?
A: In some ways, the abdominal pain and nausea from appendicitis can feel similar to the discomfort caused by gas, constipation, indigestion or stomach flu. However, the pain caused by appendicitis is usually localized to the lower right side of the abdomen, far more severe and tends to increase in intensity.
Pressing on the abdominal area will increase the pain from acute appendicitis, as will passing gas or belching. Acute appendicitis also usually occurs with a high fever.
As acute appendicitis can progress from the first signs to rupture in 24-72 hours, it is important to visit a hospital as soon as acute appendicitis is suspected. Signs may include fever or digestive upset, combined with abdominal pain on the right side of the abdomen that becomes more intense instead of abating. Sometimes the symptoms of appendicitis do not follow a predictable pattern, though, so a person experiencing unusual abdominal pain that lasts for longer than four hours should seek a diagnosis from a doctor urgently, especially if any other symptoms are also present.
Q: Is there always a fever with appendicitis?
A: Acute appendicitis sometimes occurs without a fever.
Q: How can appendicitis be prevented?
A: There is no known way to prevent appendicitis, but it does seem to occur less commonly among people who eat a diet rich in fruits, vegetables and fiber.
Q: Are there any risks associated with an appendectomy (appendicectomy)?
A: An appendectomy – the surgical procedure to remove the appendix – is generally considered routine. However, though the risk is low, there are certain risks associated with an appendectomy, just as there are with any surgical procedure. These risks include:
- Excessive bleeding
- The formation of an abscess
- Abdominal inflammation
Before undergoing an appendectomy, be sure to discuss the possible complications with your doctor.
Q: What happens if my appendix bursts?
A: As soon as the warning signs of appendicitis appear (abdominal pain, loss of appetite, nausea, etc) it is important to seek emergency medical attention to ensure the appropriate treatment is received. If this does not happen and the appendix bursts, potentially life threatening infections can result. If bacteria from a burst appendix reaches the peritoneum (the inner lining of the belly), this can result in an infection known as peritonitis. Signs of peritonitis include: severe continuous abdominal pain, abdominal swelling, vomiting and fever. Another possible consequence of a burst appendix is the formation of an abscess. Both peritonitis and an abscess can be treated with antibiotics (most likely administered intravenously) but require urgent medical attention.
Johns Hopkins Medicine. “Articles & Answers: Burst Appendix or Stomach Flu?.” Accessed: August 20, 2017 ↩
The Obstetrician and Gynecologist. “Appendicitis in pregnancy: how to manage and whether to deliver”. 2015. Accessed 12 December 2018. ↩
Medscape. “Peritonitis and Abdominal Sepsis Clinical Presentation”. 11 January 2017. Accessed 7 December 2018. ↩
Society of American Gastrointestinal and Endoscopic Surgeons. “LAPAROSCOPIC APPENDIX REMOVAL (APPENDECTOMY) SURGERY PATIENT INFORMATION FROM SAGES”. 1 March 2015. Accessed 7 December 2018. ↩