Appendicitis: Causes, Symptoms, Diagnosis, and Treatment
Also known as: acute appendicitis
Overview
Appendicitis is the acute inflammation of the appendix, a small finger-shaped pouch attached to the cecum in the lower right abdomen. It is one of the most common abdominal surgical emergencies in the United States. It can occur at any age but is especially common between ages 10 and 30. Without prompt treatment, appendicitis can progress to rupture and peritonitis, which can be life-threatening.
Causes and risk factors
Appendicitis usually results from an obstruction of the appendix, leading to bacterial overgrowth and inflammation. Main causes include:
- A fecalith (hardened stool) blocking the appendix
- Enlarged lymph nodes (mesenteric adenitis), often from a viral infection
- The presence of intestinal parasites or foreign objects
- An appendiceal carcinoid tumor (rarer)
Symptoms
Clinical signs of appendicitis usually follow a typical progression:
- Abdominal pain starting around the belly button, then moving to the lower right abdomen (McBurney’s point), the hallmark sign
- Nausea and vomiting, usually starting after the pain
- Low-grade fever, which can rise with complications
- Loss of appetite and reduced bowel activity
- Abdominal guarding when pressing on the lower right abdomen
- Rarely, diarrhea or urinary symptoms if the appendix is in an unusual position
Diagnosis
Diagnosis is based on clinical examination, confirmed with additional tests:
- Blood work: complete blood count (elevated white blood cells) and elevated C-reactive protein (CRP)
- Abdominal ultrasound: a first-line, radiation-free test
- Abdominal or pelvic CT scan: the gold standard when the diagnosis is unclear, with over 95% accuracy
- The Alvarado score helps assess clinical risk
Treatments
Treatment for appendicitis depends on the stage and severity:
- Surgical appendectomy: the standard treatment, performed urgently by laparoscopy in most cases
- Antibiotics alone: an alternative sometimes considered for uncomplicated cases (amoxicillin-clavulanate or IV cephalosporins), with close monitoring; about 1 in 4 people treated this way need an appendectomy within a year
- Percutaneous drainage: for an established appendiceal abscess, before delayed surgery
- Supportive care: pain relievers (acetaminophen, opioids if needed), anti-nausea medication, and IV fluids before surgery
- For peritonitis: extensive surgery with peritoneal lavage and prolonged antibiotic treatment
Prevention
There is no guaranteed way to prevent appendicitis, but certain measures may help reduce the risk:
- Eat a high-fiber diet (fruits, vegetables, legumes) to support healthy digestion
- Stay well hydrated every day
- Treat gastrointestinal infections and intestinal parasites promptly
- See a doctor without delay for persistent abdominal pain to avoid complications
- Keep up with regular medical checkups, especially with a history of digestive issues
When should you see a doctor?
Seek emergency care if you have intense, persistent abdominal pain on the right side, along with fever, nausea, or vomiting. Any rapid worsening, abdominal rigidity, or signs of shock (paleness, feeling faint) require calling 911 immediately. Do not wait: an untreated appendix can burst and lead to peritonitis, and the risk of rupture rises the longer treatment is delayed.
Sources
- MedlinePlus: Appendicitis, U.S. National Library of Medicine health information
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), official U.S. government research
- MedlinePlus Medical Encyclopedia: Appendicitis, U.S. National Library of Medicine
- Appendicitis (StatPearls, NCBI Bookshelf), NIH-hosted clinical reference: CT accuracy above 95%, the Alvarado score, laparoscopic appendectomy as the preferred approach, rupture risk rising the longer treatment is delayed, and the roughly 1-in-4 appendectomy rate within a year after antibiotic-only treatment