Febrile neutropenia should be considered a medical emergency in children receiving chemotherapy. Neutropenia is defined as an absolute neutrophil count (total white blood cell count in thousands multiplied by the fraction of segmented neutrophils and bands) <500/μL or an absolute neutrophil count <1,000/μL and falling. Blood counts are expected to nadir 7 to 10 days following chemotherapy. Fever is defined as an oral temperature >38.5°C, an axillary temperature >37.5°C or three low-grade temperatures (38.0°–8.4°C orally or 37.0°–37.4°C axillary) in 24 hours. Rectal temperatures should not be taken in neutropenic patients due to the increased risk of infection from gastrointestinal flora. Febrile patients who have recently received chemotherapy should be considered at high risk of infection due to their immunocompromised state and receive intravenous antibiotics within 1 hour of presenting to the emergency department.

Evaluation of a patient with fever and suspected neutropenia should include careful history and physical examination, keeping in mind that due to the lack of neutrophils, the erythema, suppuration, and edema that commonly accompany infections may be lacking. For example, a patient who has exquisite tenderness over a central line site without concomitant erythema, edema, or suppurative drainage should still be treated for cellulitis. The same can be said for patients with respiratory symptoms without infiltrate on chest x-ray or urinary symptoms without pyuria. Laboratory evaluation should include complete blood count, creatinine, and liver enzymes (to use as a baseline when monitoring for antibiotic/antifungal toxicity), and blood cultures. Some debate exists if a peripheral culture should be collected in addition to cultures from the patient’s central line. Aerobic, anaerobic, and fungal cultures should be collected from all sites (including each lumen of the central line). Urinalysis and chest x-ray are not indicated unless the patient has significant symptom- atology.