Appendicitis

Description

• 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

• 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

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

• 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

Etiology

• 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