Conditions guide

Appendicitis

Appendicitis is inflammation of the appendix, a small finger-shaped pouch attached to the large intestine. It is a common cause of sudden abdominal pain and is generally treated as a medical emergency because an inflamed appendix can burst.

Last updated 3 sources

At a Glance

  • Appendicitis is one of the most common reasons for emergency abdominal surgery.
  • It can happen at any age but is most common in teens and young adults.
  • Pain often begins around the belly button and moves to the lower right abdomen.
  • Diagnosis typically involves an exam, blood tests, and imaging such as ultrasound or CT.
  • Surgical removal of the appendix (appendectomy) is the standard treatment, and antibiotics alone are an option in some cases.
  • A ruptured appendix can cause a serious infection of the abdominal lining (peritonitis).

What It Is

The appendix sits in the lower right part of the abdomen, where the small and large intestines meet. Its exact function is not fully understood, and people can live normally without it.

Appendicitis usually develops when the opening of the appendix becomes blocked. Bacteria then multiply inside, causing swelling, pus, and pressure. Without treatment, the wall of the appendix can weaken and tear (perforate), spilling infected material into the abdomen.

Symptoms typically develop over hours to a day or two. Because the timing of rupture is hard to predict, suspected appendicitis is generally evaluated urgently.

Common Terminology

Appendix
A small, narrow pouch that extends from the beginning of the large intestine (the cecum).
Appendectomy
Surgery to remove the appendix, often done laparoscopically through small incisions.
Perforation
A tear or hole in the wall of the appendix, also called a ruptured or burst appendix.
Peritonitis
Inflammation and infection of the peritoneum, the lining of the abdominal cavity, which can follow a ruptured appendix.
Abscess
A walled-off pocket of pus that may form around the appendix after it ruptures.
Rebound tenderness
Pain that worsens when pressure on the abdomen is quickly released, a sign that the abdominal lining may be irritated.
McBurney's point
A spot in the lower right abdomen where tenderness is classically felt in appendicitis.

Common Causes and Associations

Appendicitis often results from a blockage inside the appendix, though the exact cause is not always clear.

  • A hardened piece of stool (fecalith or appendicolith) can block the opening of the appendix.
  • Swelling of lymphoid tissue in the wall of the appendix, sometimes after an infection, can cause blockage.
  • Less commonly, tumors, parasites, or foreign bodies may block the appendix.
  • Appendicitis is most common between the ages of about 10 and 30, but it can occur at any age.
  • It is not caused by anything a person did, and it generally cannot be prevented.

Symptoms and Features

This is a general description, not a diagnostic checklist. Symptoms vary, and young children, older adults, and pregnant people often have less typical symptoms.

  • Pain that often starts as a dull ache near the belly button and then shifts to the lower right abdomen, becoming sharper.
  • Pain that worsens with movement, coughing, walking, or jarring motions such as going over bumps in a car.
  • Loss of appetite, often one of the earliest signs.
  • Nausea and vomiting, usually beginning after the pain starts.
  • Low-grade fever that may rise if the appendix ruptures.
  • Constipation, diarrhea, or bloating in some people.
  • A sudden easing of pain followed by more widespread severe pain may occur after rupture.

Tests and Evaluation

There is no single test for appendicitis. Clinicians combine findings from the history, exam, lab tests, and imaging.

  • A physical exam checks for tenderness in the lower right abdomen and signs of irritation of the abdominal lining.
  • Blood tests often look for a raised white blood cell count, which suggests infection or inflammation.
  • A urine test may help rule out a urinary tract infection or kidney stone.
  • A pregnancy test is commonly done for people who could be pregnant, since some pregnancy-related conditions can cause similar pain.
  • A CT scan of the abdomen is frequently used in adults to confirm appendicitis or find other causes of pain.
  • Ultrasound is often used first in children and pregnant people to avoid radiation, and MRI may be used in pregnancy.

Treatment Overview

Treatment is decided by the medical team, usually in a hospital setting.

  • Appendectomy, most often done laparoscopically, is the standard treatment for appendicitis.
  • Antibiotics are given around the time of surgery to treat or prevent infection.
  • For some cases of uncomplicated appendicitis, treatment with antibiotics alone may be considered, although the appendicitis can come back.
  • If the appendix has ruptured, treatment may involve a longer course of antibiotics and sometimes cleaning of the abdominal cavity.
  • An abscess may first be drained through the skin with imaging guidance, with surgery sometimes done later.
  • Many people go home within a day or two after uncomplicated laparoscopic surgery, while recovery is often longer after rupture.

When Professional Care May Be Discussed

Severe or worsening abdominal pain, especially in the lower right abdomen or with fever, vomiting, or a rigid, tender belly, is generally treated as a medical emergency; in the US, people are advised to call 911 or seek emergency care.

  • Abdominal pain that is getting steadily worse over hours is generally evaluated promptly by a healthcare professional.
  • Health organizations generally advise against using laxatives, enemas, or heating pads for unexplained severe abdominal pain before it is evaluated.
  • Pain that becomes severe and spreads across the whole abdomen can be a sign of rupture and is generally considered urgent.
  • After surgery, fever, increasing pain, redness or drainage at incisions, or persistent vomiting are typically reported to the surgical team.
  • Abdominal pain in pregnancy, young children, or older adults is often evaluated with extra caution because symptoms can be less typical.

Questions to Ask a Healthcare Professional

General questions people often find useful to bring to an appointment:

  • What tests are generally used to diagnose appendicitis, and why might imaging be needed?
  • What is the difference between uncomplicated and complicated (ruptured) appendicitis?
  • When might antibiotics alone be considered instead of surgery?
  • What is the difference between laparoscopic and open appendectomy?
  • What does recovery after an appendectomy usually involve?
  • What other conditions can cause pain similar to appendicitis?
  • What signs after surgery are typically reported to the care team?

Sources

This guide was written in plain language from the following authoritative references.

  1. Appendicitis — MedlinePlus (U.S. National Library of Medicine)
  2. Appendicitis — National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
  3. Appendicitis — NHS

Last updated October 8, 2026. FreeDoc guides are general educational information and are not a substitute for care from a qualified professional.