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J. Craig Egan and John J. Aiken

Appendicitis is the most frequent pediatric surgical emergency, and appendectomy is the second most commonly performed pediatric surgical procedure. The incidence of appendicitis peaks between 10 and 19 years of age.1 In children older than 4 years with an elevated white blood cell (WBC) count, the most common diagnosis is appendicitis.

Clinical Presentation and Diagnosis

Appendicitis is primarily a clinical diagnosis. The classic history of periumbilical pain, with anorexia and nausea, followed by localization of pain in the right lower quadrant is more reliable than right lower quadrant pain itself for diagnosis.2 Findings of fever, right lower quadrant tenderness, a Rovsing’s sign (palpation of the lower left quadrant of a person’s abdomen results in more pain in the right lower quadrant), or percussion tenderness with rebound are all highly suggestive of appendicitis. Right lower quadrant pain during rectal examination may suggest inflammation of a retrocecal appendix. The pain in appendicitis is continuous and generally does not get better. The pain is usually present even when the patient is lying still. Occasionally a child complains of right lower abdominal pain while walking, or refuses to stand up or walk.

Following the onset of pain, fever, tachycardia, and leukocytosis are commonly observed. An elevated WBC count or left shift are helpful markers for the diagnosis of appendicitis in children with nontraumatic acute abdominal pain.3 The diagnostic accuracy of the WBC is better than C-reactive protein (CRP), but even when both are normal, there is a small chance (between 0% and 5%) that appendicitis is present.4

An abdominal x-ray might show the presence of an appendix stone (fecalith) in the right lower area of the abdomen which suggests that appendicitis may be present (eFig. 413.1), but a fecalith is only seen on x-ray in a few patients (15%) so routine abdominal x-ray is not recommended in patients with likely appendicitis.

eFigure 413.1

Acute appendicitis. An oval calcification and appendiceal lumen filled with gas are seen (arrow). At surgery, gangrenous appendicitis with perforation and an obstructing fecolith were found.

(From Chen MYM, Pope, Jr. TL, Otto DJ: Basic Radiology. 2nd ed. New York: McGraw-Hill, 2011.)

The introduction of diagnostic testing including ultrasound and abdominal computerized tomography (CT) has marginally improved the diagnostic accuracy for appendicitis. Ultrasound examination is especially useful in teenage girls in whom gynecology conditions such as an ovarian cyst are being considered, and in pregnant women. The typical finding of appendicitis on ultrasound is a round, tender, stiff, blind-ending structure that is greater than 6 mm in diameter, localized next to cecum. Abdominal CT can be up to 96% accurate for prediction of acute appendicitis, with typical findings of an enlarged, swollen appendix with a thickened wall, periappendiceal standing and often a ...

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