Appendicitis

Digestive Inflamed appendix

A blocked, inflamed appendix in the lower-right abdomen that can burst if not treated.

Educational summary only — not medical advice, and no substitute for assessment by a clinician. Diagrams are simplified illustrations.

The appendix is a small worm-like tube off the cecum; when its opening blocks, it swells, inflames and can burst.

Overview

The appendix is a small, finger- or worm-shaped pouch that branches off the start of the large intestine (the cecum), low on the right side of the abdomen. Appendicitis is inflammation of this pouch — one of the most common reasons for emergency abdominal surgery. It typically develops over hours to a couple of days and, untreated, can burst.

How the system normally works

The appendix is a narrow dead-end tube opening into the cecum. It has no essential digestive role and can be removed without lasting harm. Its narrowness, however, makes it prone to becoming blocked.

What goes wrong

When the appendix's opening becomes blocked — by hardened stool, swollen lymph tissue, or rarely a seed or growth — mucus and bacteria are trapped inside. Pressure rises, the wall swells, and the blood supply is squeezed. Without treatment the wall can die and perforate (burst), spilling infection into the abdominal cavity (peritonitis) or forming an abscess.

Diagram showing three stages of appendicitis: normal appendix, inflamed swollen appendix, and burst appendix leaking pus. — Progression over hours to a day or two: a blocked appendix swells, its blood supply is choked, and untreated it can perforate and leak infection into the belly.

Symptoms and why they happen

Pain that starts around the navel, then shifts to the lower-right belly — early stretching causes vague central pain; later, the inflamed appendix irritates the overlying lining, localising the pain.
Pain worse with movement, coughing, or pressing then releasing (rebound) — the irritated lining.
Loss of appetite, nausea, vomiting.
Low-grade fever.

Causes and risk factors

Appendicitis can affect anyone but is most common between the ages of about 10 and 30. There is no reliable way to prevent it.

How it's diagnosed

Diagnosis combines the history and examination (tenderness at McBurney's point in the lower right) with blood tests showing infection and imaging — ultrasound (often first in children and pregnancy) or CT — to confirm and to exclude mimics.

Diagram of the abdomen marking McBurney's point in the lower right and an arrow showing pain migrating from the navel. — Classic pattern: pain starts vaguely around the navel, then settles and sharpens at McBurney's point in the lower-right abdomen.

Treatment and management

The usual treatment is surgical removal of the appendix (appendicectomy), most often by keyhole surgery, along with antibiotics. Selected uncomplicated cases may be treated with antibiotics alone, though some still come to surgery later. A burst appendix needs prompt surgery and a longer antibiotic course; an abscess may be drained first.

Possible complications

The main complication is perforation leading to peritonitis or an abscess — more likely the longer treatment is delayed, which is why timely assessment matters.

Prevention and outlook

There is no proven prevention, but the outlook after timely surgery is excellent and recovery is usually quick. Living without an appendix has no significant downside.

When to seek emergency care

Increasing lower-right belly pain with fever and vomiting — seek urgent assessment.
Sudden relief followed by spreading, severe belly pain and a rigid abdomen — the appendix may have burst.