The appendix is a small, finger‑shaped pouch attached to the first part of the large intestine, usually in the lower right side of the abdomen. For most people, it does not play a critical role in digestion. Some research suggests it may support the immune system and healthy gut bacteria—especially early in life—by acting as a “safe house” for beneficial bacteria that can repopulate the colon after diarrhea or infection. However, other parts of the digestive and immune systems can compensate, so the appendix is not generally considered essential for survival. People can typically live completely normal, healthy lives after their appendix is removed.
What is appendicitis?
Appendicitis is inflammation of the appendix, usually caused by blockage of its opening by stool, swollen lymph tissue, or rarely a tumor. When the appendix becomes blocked, bacteria multiply inside, causing swelling, infection, and sometimes rupture
Common causes and risk factors include blockage of the appendix opening by hardened stool or debris, leading to trapped bacteria and infection; swelling of lymphoid tissue in the appendix after infections; or less commonly, growths such as tumors that obstruct the appendix.
Signs and symptoms of appendicitis
Appendicitis usually begins suddenly and gets worse over several hours.
Seek urgent medical care if you notice:
- Pain that starts near the belly button and moves to the lower right abdomen, often worsening over hours
- Tenderness in the lower right side of the abdomen, especially when pressed or with movement, coughing, or walking
- Loss of appetite; a common early sign
- Nausea and vomiting – often following the onset of pain
- Low-grade fever – may rise if the appendix ruptures
- Change in bowel habits, such as constipation or diarrhea
These symptoms can overlap with other conditions, so prompt evaluation is critical.
How is appendicitis diagnosed?
Diagnosis combines careful review of history, physical exams, and targeted tests. A clinician evaluates when the pain began, where it is located, and what makes it better or worse, and checks for tenderness in the lower right abdomen and signs of peritonitis, such as pain with gentle pressure and release.
Blood tests can reveal signs of infection, including an elevated white blood cell count, while urine tests help rule out urinary tract or kidney problems. Imaging studies are often used to support the diagnosis. Ultrasound is frequently used, especially in children and pregnant patients; CT scans of the abdomen and pelvis are commonly used in adults to confirm appendicitis and assess for complications; and MRI may be chosen when it is important to minimize radiation exposure.
Medical and surgical treatment
Before deciding on surgery, antibiotics can be administered to treat the infection. In some carefully selected patients with early, uncomplicated appendicitis, antibiotics alone may be considered, but many will still eventually need surgery. When the appendix has ruptured and an abscess has formed, treatment may include drainage of the abscess, intravenous antibiotics, and then delayed (interval) appendectomy.
Appendicitis is usually treated with surgery to remove the appendix, called an appendectomy. In laparoscopic or robotic (minimally invasive) appendectomy, surgeons make several small incisions and use a camera and fine instruments to remove the appendix. Minimally invasive surgery often results in less pain, shorter hospital stays, and faster return to normal activities.
In open appendectomy, a single larger incision is made. This approach is often used when the appendix has ruptured or when anatomy or prior surgery makes laparoscopy difficult.