Acute appendicitis
Acute appendicitis is luminal obstruction and infection of the vermiform appendix presenting as migratory periumbilical-to-right-lower-quadrant pain, diagnosed by the classic history and exam plus confirmatory imaging (CT in adults, ultrasound or MRI in children and pregnancy), and treated with prompt appendectomy or, in selected uncomplicated cases, antibiotics alone.
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What this article covers
- Overview
Definition: acute inflammation and infection of the vermiform appendix following luminal obstruction, producing a closed-loop process that progresses from visceral distension to peritoneal irritation.
- Epidemiology
Common life-threatening cause of RLQ pain: along with ectopic pregnancy, one of the two classic life-threatening causes of acute RLQ abdominal pain that must be excluded in patients of reproductive age.
- Risk factors
Luminal obstruction of the appendix: a fecalith, lymphoid hyperplasia, or (less commonly) an appendicolith, tumor, or parasite obstructs the appendiceal orifice and initiates the closed-loop process.
- Pathophysiology
Luminal obstruction initiates a closed-loop process: a fecalith (adults) or lymphoid hyperplasia (children) occludes the appendiceal lumen, trapping secretions and gas.
- Clinical features
Migratory pain, the hallmark: dull periumbilical pain (visceral, T8 to T10) that over several hours becomes sharp, severe, and constant, localizing to the RLQ (parietal) as inflammation reaches the…
- Differential diagnosis
Ectopic pregnancy: a life-threatening RLQ or pelvic pain mimic in any female of reproductive age; a pregnancy test is mandatory before further workup, and hemodynamic instability suggests rupture (ectopic pregnancy).
- Diagnosis
Establish the diagnosis from the compatible clinical picture, then confirm further when uncertain: the classic pattern (anorexia followed by periumbilical pain migrating to and localizing in the RLQ…
- Management
Resuscitate first: make the patient NPO, start IV fluids, and control pain with NSAIDs, acetaminophen, or opioids; adequate analgesia does not meaningfully delay diagnosis or mask peritoneal signs and should not be withheld.
- Complications
Perforation and diffuse peritonitis: the most serious complication, converting a localized process into generalized peritoneal contamination and sepsis, the primary driver of morbidity.
- Prognosis
Excellent with timely appendectomy: uncomplicated appendicitis treated with prompt appendectomy has a low mortality rate and rapid recovery.
- Prevention
No established primary prevention: no screening test or modifiable risk factor reliably prevents the luminal obstruction that initiates appendicitis.
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