• Most common abdominal emergency
  • Most common indication for emergency surgery worldwide
  • Acute obstruction of appendiceal lumen results in distension followed by ischemia, bacterial overgrowth, and eventual perforation of the viscus
  • Classic pain migration:
    • Periumbilical pain: Appendiceal distension stimulates stretch receptors, which relay pain via visceral afferent pain fibers to tenth thoracic ganglion
    • RLQ pain: As inflammation extends to surrounding tissues, pain occurs owing to stimulation of parietal nerve fibers and localizes to position of appendix

Pediatric Considerations
  • 28–57% misdiagnosis in patients <12 yr (nearly 100% in patients <2 yr)
  • 60–86% perforation rate in children <4 yr
  • Perforation correlates strongly with delayed diagnosis

Geriatric Considerations
  • Decreased inflammatory response
  • Up to 3 times more likely to have perforation owing to anatomic changes
  • Diagnosis often delayed owing to atypical presentations

Pregnancy Considerations
  • Slightly higher rate in second trimester compared to first/third/postpartum periods
  • Increased perforation rate (25–40%), highest in third trimester
  • RLQ pain remains the most common symptom
  • 5–10% fetal loss, up to 24% in perforated appendicitis


  • Luminal obstruction of appendix
  • Appendiceal lumen becomes distended, inhibiting lymphatic and venous drainage
  • Bacterial invasion of wall, with edema and blockage of arterial blood flow
  • Perforation and spillage of contents into peritoneal cavity, causing peritonitis (usually 24–36 hr from onset)
  • May wall off and form abscess
  • Gram-negative rods and anaerobic organisms predominate

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