Appendicitis

Description

• Most common abdominal emergency
• Acute obstruction of appendiceal lumen results in distension followed by organ ischemia, bacterial overgrowth, and eventual perforation of the viscus
• Pain migration:
  • Periumbilical pain: Appendiceal distension stimulates stretch receptors, which relay pain via visceral afferent pain fibers to 10th 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)
• 70–90% perforation rate in children <4 yr
• Perforation correlates strongly with delayed diagnosis.

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

• Slightly higher rate in 2nd trimester compared to 1st/3rd/postpartum periods
• Increased perforation rate (25–40%), highest in 3rd trimester
• RLQ pain remains the most common symptom
• 7–10% 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