Appendicitis most commonly affects children age 10–19, with an overall incidence of approximately 20 cases per 10,000 population annually.Among those under age 20, infants age 0–4 have the lowest incidence of appendicitis (2 cases per 10,000 annually), but up to two-thirds will present with perforation. Perforation is common because infants often present later in their disease course and because of the difficulty in obtaining an accurate history. The diagnosis is further complicated by diseases of childhood that can mimic appendicitis. For instance, mesenteric adenitis, an inflammation of the mesenteric lymph nodes secondary to upper respiratory tract infection, can present with fever and right lower quadrant pain. Streptococcal pharyngitis and bacterial meningitis can also present with fever, nausea, and abdominal pain. These diagnoses should be considered when evaluating children for suspected appendicitis.
In children with an equivocal history and physical examination, CT has been shown to be highly accurate in diagnosing appendicitis. Garcia Pena and associates compared ultrasonography and rectal contrast CT in 139 children with suspected appendicitis and found CT to be more sensitive (97% for CT, 44% for ultrasound), more specific (94% for CT, 93% for ultrasound), and more accurate (94% for CT, 76% for ultrasound). CT correctly changed the management of 73% of patients, while ultrasound correctly changed 19%. The use of CT can be recommended for children with one caveat. The radiation from a CT in childhood theoretically causes a small increase in the lifetime risk of certain cancers.Therefore, clinicians should consider the risks and benefits of CT, and efforts should be directed toward reducing radiation dose when imaging children.