Appendicitis

Appendicitis is inflammation of the appendix, a thin, finger-shaped structure attached to the first part of the large bowel. In everyday speech, this organ is often simply called “the appendix”. Appendicitis can occur at any age; although it is more common in childhood and young adulthood, it can also occur in later life.

The appendix is known to have some functions related to the immune system. Nevertheless, surgical removal of the appendix does not cause any known significant deficiency in the immune or digestive system.

Appendicitis is considered in two main groups:

• Uncomplicated appendicitis: There is inflammation in the appendix, but perforation, an abscess or widespread infection inside the abdomen has not developed.
• Complicated appendicitis: The appendix has perforated, an abscess has formed around it or the inflammation has spread into the abdominal cavity.

This distinction is important in determining the treatment to be used and the duration of antibiotics. Current guidelines recommend that patients with suspected appendicitis receive a medical assessment without delay [1,2].

If there is worsening abdominal pain, hardening of the abdomen, persistent vomiting, marked weakness, a feeling of faintness or high fever, you should go to the nearest emergency department.

What symptoms does appendicitis cause?

The most common symptom of appendicitis is abdominal pain. In the classic case, the pain:

• First starts around the navel or in the middle of the abdomen.
• Settles in the lower right part of the abdomen within a few hours.
• Can get worse with walking, coughing, jolting or sudden movement.
• Can become more constant and severe over time.

The pain may be accompanied by the following symptoms:

• Loss of appetite
• Nausea and vomiting
• Mild or high fever
• Tenderness and bloating of the abdomen
• Constipation or diarrhoea
• Difficulty passing wind
• In some patients, discomfort when passing urine

Not every patient has all of the symptoms. Because the position of the appendix inside the abdomen can vary from person to person, the location of the pain can also differ. Particularly in children, pregnant women and older people, the symptoms may be milder, vaguer or unusual.

Why does appendicitis develop?

The exact cause of appendicitis cannot be identified in every patient. In some patients, the inside of the appendix can become blocked by:

• A piece of hardened stool (faecalith or appendicolith),
• Swelling of the immune tissue,
• Less commonly, a parasite, a foreign body or a tumour. After the blockage, pressure inside the appendix can rise, bacteria can multiply and inflammation can develop.

Appendicitis is not contagious. It is generally not caused by a particular food eaten or by anything the person has done wrong, and there is no known method that reliably prevents it.

A diagnosis of appendicitis is not made on the basis of a single symptom or blood test. The doctor assesses the patient’s complaints, examination findings, blood and urine tests and, when necessary, imaging results together [1,2].

Examination and laboratory tests

Your doctor will ask when the pain started, whether it has moved and which symptoms accompany it. During the abdominal examination, the location of the tenderness and whether the abdominal muscles are rigid are assessed.

The tests that may be requested are:

• Blood count and CRP: These give information about inflammation in the body. However, normal values alone do not definitely rule out appendicitis.
• Urine test: Helps assess causes of similar pain, such as a urinary tract infection or a kidney stone.
• Pregnancy test: May be done in patients who could be pregnant, to distinguish emergencies such as an ectopic pregnancy and to choose the imaging method.

Clinical scoring systems such as the AIR, Alvarado and Adult Appendicitis Score can help to determine the likelihood of appendicitis. However, these scores do not replace the doctor’s examination and any necessary imaging [1].

Which imaging method is used?

• Ultrasonography: Because it does not involve radiation, it is the first-choice method, particularly in children and pregnant women. However, the appendix may not be clearly visible on ultrasound in every patient.
• Computed tomography (CT): In adults, it has very high diagnostic accuracy when the diagnosis is uncertain. In suitable patients, low-dose CT may be preferred.
• Magnetic resonance imaging (MRI): Can be used particularly in pregnant women or when radiation needs to be avoided.

Imaging does not only help with the diagnosis of appendicitis; it can also show conditions that change the treatment decision, such as an appendicolith, perforation, an abscess and widespread inflammation.

Treatment is planned according to whether the appendicitis is uncomplicated or complicated, and according to the patient’s age, general state of health and imaging findings.

How is appendicitis surgery performed?

The definitive and established treatment for appendicitis is appendicectomy, that is, surgical removal of the appendix. Today, laparoscopic (keyhole) appendicectomy is the standard surgical approach in suitable patients [1,2].

In keyhole surgery, the appendix is removed using a camera and fine surgical instruments inserted through a few small incisions in the abdomen. This method is generally associated with advantages such as:

• Smaller incisions,
• Less pain after the operation,
• A shorter hospital stay,
• An earlier return to daily life.

If the appendix has perforated, there is widespread inflammation inside the abdomen or it is not possible to continue safely with the keyhole method, open surgery may be preferred. Converting an operation that started as keyhole surgery to open surgery for safety reasons is not a failure.

In patients with uncomplicated appendicitis whose general condition is stable, performing the operation within the first 24 hours after diagnosis is generally considered safe. However, if there is perforation, widespread inflammation of the peritoneum (the lining of the abdomen) or a deterioration in general condition, more urgent intervention is needed [1].

Are antibiotics used before and after surgery?

Before surgery, a single dose of antibiotic is usually given into a vein to reduce the risk of infection.

After surgery for uncomplicated appendicitis, most patients do not need to continue antibiotics. In perforated or complicated appendicitis, on the other hand, antibiotic treatment is given. If the source of infection inside the abdomen has been adequately controlled by surgery, current guidelines state that short treatment of about 2–3 days may be sufficient for most patients. The duration is individualised according to the patient’s temperature, blood values, operative findings and clinical recovery [1].

Can appendicitis be treated with antibiotics alone?

In some suitably selected adult patients in good general condition, in whom imaging has confirmed uncomplicated appendicitis, antibiotic treatment may be considered instead of surgery. This approach is not suitable for every patient, and the advantages of the treatment and the risk of recurrence should be assessed together by the patient and the surgeon [1–4].

The advantage of antibiotic treatment is the possibility of avoiding surgery and anaesthesia at first. However:

• There is a possibility of not improving during treatment and needing surgery.
• Appendicitis can recur months or years later.
• Repeated hospital visits may be needed.
• The opportunity for pathological examination of a removed appendix is lost.

Long-term studies have shown that a large proportion of patients treated with antibiotics later need an appendicectomy. In the 10-year results of the APPAC trial, this rate was reported to be about 44% [3]. In the CODA trial, about half of the patients who started with antibiotics had an appendicectomy within 3–4 years [4].

If there is a piece of hardened stool called an appendicolith, the likelihood of antibiotic treatment failing and complications developing is higher. For this reason, surgery is considered more strongly in patients with an appendicolith [1,4].

Antibiotic treatment alone is not appropriate in patients with widespread inflammation of the peritoneum, perforation, uncontrolled infection, a suspected tumour or a deterioration in general condition. Antibiotic treatment is not something that can be started at home without seeing a doctor.

What happens if an abscess or an appendix mass has developed?

The development of a localised abscess or an inflamed mass of tissue around the appendix is called an “appendiceal abscess” or “appendix mass” (plastron). In patients whose general condition is stable, the options are:

• Antibiotic treatment,
• For suitable abscesses, image-guided drainage,
• Early laparoscopic surgery at experienced centres.

Which method is chosen depends on the size of the abscess, the patient’s condition and the experience of the centre.

It is not essential for every patient who recovers with antibiotics or drainage to automatically have surgery later. However, a planned appendicectomy may be needed in those with recurring complaints or a suspected tumour. Particularly in adults aged 35 and over in whom an abscess around the appendix has been found, colonoscopy, abdominal imaging and the option of a delayed appendicectomy should be considered because of the possibility of an underlying tumour of the appendix or large bowel [1].

Is the appendix sent for pathology?

The appendix removed during surgery is examined in the pathology laboratory. This examination confirms the diagnosis and makes it possible to identify rare findings such as a tumour of the appendix, a neuroendocrine tumour or other inflammatory diseases.

After an uncomplicated laparoscopic appendicectomy, most patients can get up on the same day or the next day and can usually be discharged within 1–2 days. The length of hospital stay varies according to the patient’s condition and the practice of the healthcare facility.

If the appendix has perforated, or an abscess or widespread infection has developed, a longer hospital stay and antibiotic treatment may be needed.

After discharge:

• Light walks can be started early on.
• Pain and tenderness at the incision sites for a few days can be expected.
• As long as there is no nausea, diet can gradually return to normal.
• In most patients, a return to desk work may be possible within about 1–2 weeks.
• The time to return to heavy lifting and strenuous exercise should be determined by the doctor according to the surgical method and the recovery.

If any of the following symptoms develops, you should contact the healthcare team:

• A rising or persistent fever
• Abdominal pain that keeps getting worse
• Persistent vomiting or being unable to eat
• Marked swelling of the abdomen
• Being unable to pass wind or stools
• Redness, swelling, foul-smelling discharge or bleeding at the incision site

1. Podda M, et al. Diagnosis and Treatment of Acute Appendicitis: 2025 Edition of the World Society of Emergency Surgery Jerusalem Guidelines. JAMA Surgery. 2026;161(3):283–295. doi:10.1001/jamasurg.2025.6218. Read the publication
2. Kumar SS, et al. SAGES Guideline for the Diagnosis and Treatment of Appendicitis. Surgical Endoscopy. 2024;38:2974–2994. doi:10.1007/s00464-024-10813-y. Read the guideline
3. Salminen P, et al. Ten-Year Follow-Up of Antibiotic Therapy Versus Appendectomy for Uncomplicated Acute Appendicitis: The APPAC Randomized Clinical Trial. 2026. PubMed record
4. CODA Collaborative. A Randomized Trial Comparing Antibiotics with Appendectomy for Appendicitis. New England Journal of Medicine. 2020;383:1907–1919. doi:10.1056/NEJMoa2014320. Read the publication