DESCRIPTION

Acute inflammation or infection of the vermiform appendix

EPIDEMIOLOGY

• Most common surgical emergency of childhood and the most common reason why parents are consulting for bellyache
• 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.
• Affects boys more commonly than girls

PATHOPHYSIOLOGY

• Acute inflammation of the appendiceal lumen is caused by obstruction (i.e., by a fecalith), hyperplastic lymphoid tissue secondary to common viral infection, or, rarely, pediatric group tumor).
• Appendix is innervated by somatic afferent nerves of the 10th dermatome overlying the epigastrium and periumbilical areas.
• In the first phase of pain, increasing wall tension of the appendix results in vague pain poorly referred to the epigastric area.
• Later, increasing wall tension and full-thickness inflammation of the appendix extend to the peritoneum of the adjacent abdominal wall and the surrounding tissues, and the second phase of pain is localized to the right lower quadrant.
• 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 rare. It can be associated with prematurity and inguinal hernia, and the diagnosis is commonly delayed as a rare disease in the first months of life.