Description

Acute inflammation or infection of the vermiform appendix

Epidemiology

• Most common surgical emergency of childhood
• Incidence rate (per 10,000 person-years):
  • 2 in 0- to 4-year olds,
  • 10 in 5- to 9-year olds,
  • 15 in 10- to 14-year olds
• 293,000 admissions in the United States in 2010
• 80,000 pediatric appendectomies per year in United States
• Most commonly seen in 2nd decade of life; <5% are aged 0 to 4 years old
• Affects boys more commonly than girls

Pathophysiology

• Acute inflammation of the appendiceal lumen is caused by obstruction (i.e., by a fecalith, calculi, parasites, hyperplastic lymphoid tissue, or tumor).
• Appendix is innervated by somatic afferent nerves of the 10th dermatome overlying the epigastrium and periumbilical areas.
• In the first phase of pain, occlusion causing increasing wall tension results in vague pain poorly referred to this area.
• Increasing wall tension and full-thickness serositis results in inflammation of surrounding tissues, and the second phase of pain is localized to the area in which the appendix is lying.
• In 85% of patients, this tenderness is located at McBurney point; however, pelvic, retrocecal, retroperitoneal, inguinoscrotal, or other orientations will result in variance of location and intensity of this pain.

Commonly Associated Conditions

Neonatal appendicitis is associated most commonly with prematurity, inguinal hernia, and Hirschsprung disease.