Radiology: Volume 255: Number 1—April 2010
Marta Hernanz-Schulman, MD
Appendicitis is an urgent condition that requires prompt surgical intervention to minimize morbidity and mortality. It is the most common pediatric surgical problem, representing 80% of pediatric surgical emergencies and 60000-80000 annual operations in the United States alone (1,2). Yet, the diagnosis is not always straightforward, particularly in younger patients who are unable to verbalize symptoms and in whom the historical timeline is imprecise. The rate of misdiagnoses at initial presentation is cited to be as high as 57% in children younger than 12 years and as high as 100% in children younger than 2 years (3). Perforation rates mirror these statistics, increasing to 23%-73% in young children and as high as 100% in infants younger than 1 year of age, compared with 16%-39% in adults. Preoperative diagnosis is reported as being uncertain in one-third to one-half of cases in which patients underwent surgery, and a negative appendectomy rate (equating with an unnecessary operation) as high as 25% has been accepted in lieu of delay in prompt surgical intervention (4).When the presentation is typical, most investigators and clinicians agree that imaging is unnecessary; however, the presentation is atypical in approximately 35%-45% of patients, and it is in this group in whom imaging is most helpful (5). Thus, the first diagnostic evaluation of the child presenting with abdominal pain suggesting acute appendicitis includes the clinical history and physical examination; results of laboratory tests, such as white blood cell count and C-reactive protein level, can be helpful but are not specific (3). In the substantial minority in whom these initial findings are equivocal, the decision tree branches as follows: the patient may be observed, risking perforation or worsening peritonitis; the patient may undergo an urgent but possibly unnecessary operation, with risk and morbidity of its own; or the patient may undergo an imaging examination.Although magnetic resonance (MR) imaging shows promise in the presurgi-cal assessment of patients who are suspected of having appendicitis (6,7), the application of this modality to the pediatric patient is as yet undeveloped and its effectiveness is unproven. Although in many ways a promising modality, the length of the MR imaging examination may substantially curtail its utility in younger patients who would need lengthy sedation. Radiolabeled white blood cell scans have also been used, but their application remains controversial in pediatric patients (8). Ultrasonography (US) and computed tomography (CT), on the other hand, have been widely applied to the diagnosis of appendicitis in pediatric patients, and there is an extensive body of literature in which researchers have reported the results of testing their sensitivity, specificity, and predictive values and the subsequent clinical outcomes.