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Causes and Incidence The etiology is not clear but appears to be related to obstruction of the appendiceal lumen by a fecal mass, stricture, or infection. Acute appendicitis is one of the most common reasons for abdominal surgery. The incidence is about 1 in 1,000 persons in the United States; the condition is most common in adolescents and young adults and is slightly more prevalent in men.

Disease Process The lumen is obstructed, blood flow is diminished, hypoxia develops, the mucosa ulcerates, and bacteria invade the wall, causing an infection and producing edema, which further impedes blood flow, causing tissue necrosis, gangrene, and perforation.

Symptoms The typical symptom is progressively severe abdominal pain, which begins in the midabdomen and shifts to the lower right quadrant after 6 to 10 hours. The pain may be accompanied by a low-grade fever, malaise, nausea, and vomiting.

Potential Complications Perforation causes peritonitis.

Diagnostic Tests

Clinical examination

Localized rebound tenderness at McBurney's point

WBCs

Moderately elevated with left shift

Laparoscopy

For visualization when diagnosis is in doubt

Treatments

Surgery

Appendectomy

Drugs

Antibiotics for prophylaxis after surgery

General

None