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- Acute inflammation of the vermiform appendix, first described by Reginald Fitz in 1886
- Arising from the base of the cecum in right lower quadrant (RLQ); can be localized anterior, posterior, medial, lateral to the cecum, as well as in the pelvis. Vascular supply by appendicular artery, a branch of the ileocolic artery. Nerve supply derived from the superior mesenteric plexus.
- Most common cause of the acute surgical abdomen
- Predominant age: 10–30 years: Rare in infancy
- Predominant sex: Slight male predominance:
- Ages 10–30: Male > Female (3:2)
- Age >30: Male = Female
- 1 case per 1,000 people per year
- Lifetime incidence 1 in every 15 persons (7%)
- Most common extrauterine surgical emergency
- No more common in pregnant vs. nonpregnant women
- Higher rate of perforation; more likely to present with peritonitis
Adolescent males, familial tendency, intra-abdominal tumors
1st-degree relative with history of appendicitis increases risk, although no direct genetic link has been found.
The cause is thought to be obstruction of the appendiceal lumen. This leads to distention, ischemia, and bacterial overgrowth. Without intervention, most cases of appendicitis will lead to perforation and subsequently abscess formation or generalized peritonitis.
Causes of obstruction:
- Fecaliths (most common)
- Lymphoid tissue hyperplasia (in children)
- Vegetable, fruit seeds, and other foreign bodies
- Intestinal worms (ascarids)
- Strictures, fibrosis, neoplasms