Appendicitis

Appendicitis is inflammation of the appendix, a small finger-shaped pouch projecting from the colon on the lower right side of the abdomen. It is a common cause of acute abdominal pain and is treated as a surgical emergency in most cases because a severely inflamed appendix can rupture, spreading infection through the abdomen (peritonitis).

Appendicitis can occur at any age but is most frequent in older children, adolescents, and young adults. Classic symptoms include pain that starts near the navel and moves to the lower right abdomen, loss of appetite, and fever. Diagnosis is clinical and often supported by imaging. Treatment is usually surgical removal of the appendix (appendectomy); selected uncomplicated cases may be managed with antibiotics alone under careful observation.

Classic features of appendicitis include:

• Pain that often begins around the navel or upper abdomen and shifts to the lower right abdomen
• Pain that worsens with walking, coughing, or jarring movements
• Loss of appetite
• Nausea and vomiting (usually after the pain starts)
• Low-grade fever that may rise as illness progresses
• Abdominal swelling
• Constipation, diarrhea, or inability to pass gas
• Tenderness when pressure is applied and released over the lower right abdomen (rebound tenderness)

Not everyone has classic symptoms. Children, older adults, and pregnant people may present atypically. A ruptured appendix can temporarily ease pain, followed by worsening illness.

Appendicitis usually results from blockage of the lumen of the appendix. Blockage may be caused by:

• A hard piece of stool (fecalith)
• Enlarged lymphoid tissue
• Parasites, foreign bodies, or tumors (less common)

Obstruction leads to bacterial overgrowth, inflammation, swelling, reduced blood flow, and potentially necrosis and perforation.

Risk factors include:

• Age — most common between the teenage years and the 30s
• Family history in some studies
• Male sex (slightly higher incidence)
• Certain dietary patterns (lower fiber intake has been associated in some research)

There is no reliable way to predict who will develop appendicitis.

Possible complications include:

• Perforation (rupture) of the appendix
• Peritonitis — infection of the abdominal lining
• Abscess formation
• Sepsis
• Surgical complications (infection, bleeding, adhesions, rarely injury to nearby structures)
• In pregnancy, increased risk of preterm labor if diagnosis is delayed

There is no proven way to prevent appendicitis. Seeking care early when symptoms develop reduces the risk of rupture and serious complications.

Diagnosis combines history, examination, laboratory tests, and imaging:

• Physical examination for localized tenderness, guarding, and peritoneal signs
• Blood tests — elevated white blood cell count and inflammatory markers support the diagnosis but are not specific
• Urinalysis — helps exclude urinary tract infection or stones
• Pregnancy test in people of childbearing potential
• Imaging — ultrasound (especially in children and pregnancy) or CT scan of the abdomen/pelvis (highly accurate in adults); MRI is an alternative in pregnancy

Scoring systems (Alvarado, Pediatric Appendicitis Score) can aid clinical decision-making.

Seek medical care promptly for abdominal pain that moves to the lower right side, especially with fever, vomiting, or loss of appetite. Go to the emergency department for severe or worsening pain, high fever, persistent vomiting, or signs of shock (dizziness, rapid heartbeat, confusion).

Standard treatment is prompt appendectomy:

• Laparoscopic appendectomy — preferred in most cases; smaller incisions, faster recovery
• Open appendectomy — used when laparoscopy is not feasible or when there is extensive infection/abscess
• Antibiotics before surgery and, for complicated appendicitis, a course afterward
• Percutaneous drainage plus antibiotics for some appendiceal abscesses, with delayed appendectomy in selected cases
• Nonoperative management with antibiotics alone may be offered for carefully selected uncomplicated appendicitis, with counseling about recurrence risk and need for follow-up

Pain control, fluids, and monitoring are provided throughout care.

After appendectomy:

• Follow wound-care and activity instructions
• Take prescribed pain medicines and antibiotics if given
• Advance diet as tolerated
• Avoid heavy lifting for the recommended period
• Report fever, increasing pain, redness, drainage, or vomiting promptly
• Attend the postoperative follow-up visit

In an emergency setting, focus on clear symptom timing (when pain started, whether it moved, presence of fever or vomiting). Note any prior abdominal surgery, current medicines, and allergies. Do not eat or drink if surgery is possible until clinicians advise otherwise.