Occult pneumonias: Empiric chest radiographs in febrile children with leukocytosis

Study objective: We sought to determine the incidence of radiographic findings of pneumonia in highly febrile children with leukocytosis and no clinical evidence of pneumonia or other major infectious source. Methods: We conducted a prospective cohort study at a large urban pediatric hospital. Clinical practice guidelines for the use of chest radiography in febrile children were established by the emergency medicine attending staff. All records of emergency department patients with leukocytosis (WBC count greater than or equal to 20,000/mm(3)), triage temperature 39.0 degrees C or higher, age 5 years or less were reviewed daily for 12 months. Physicians completed a questionnaire to note the diagnosis, the presence of respiratory symptoms and signs, and the reason for the chest radiograph (if one was obtained). Patients were excluded for immunodeficiency, chronic lung disease, or major bacterial sources of infection other than pneumonia. Pneumonia was defined by an attending radiologist's reading of the radiograph. Results: We studied 278 patients. Chest radiographs were obtained in 225 for the following reasons: 79 because of respiratory findings suggestive of pneumonia and 146 because of leukocytosis and no identifiable major source of infection. Fifty-three patients did not undergo radiography. Pneumonia was found in 32 of 79 (40%; 95% confidence interval, 20% to 52%) of those with findings suggestive of pneumonia and in 38 of 146 (26%; 95% confidence interval, 19% to 34%) of those without clinical evidence of pneumonia. If patients who did not have a radiograph are assumed to not have pneumonia, the minimum estimate of occult pneumonia was 38 of 199 patients (19%; 95% confidence interval, 14% to 25%). Conclusion: Empiric chest radiographs in highly febrile children with leukocytosis and no findings of pneumonia frequently reveal occult pneumonias. Chest radiography should be considered a routine diagnostic test in children with a temperature of 39 degrees C or greater and WBC count of 20,000/mm(3) or greater without an alternative major source of infection.