Evaluation of fever in the emergency department

Background Fever is one of the most common complaints in the emergency department (ED) and is more complex than generally appreciated. The broad differential diagnosis of fever includes numerous infectious and non-infectious etiologies. An essential skill in emergency medicine is recognizing the pitfalls in fever evaluation. Objective of review This review provides an overview of the complaint of fever in the ED to assist the emergency physician with a structured approach to evaluation. Discussion Fever can be due to infectious or non-infectious etiology and results from the body's natural response to a pyrogen. Adjunctive testing including C-reactive protein, erythrocyte sedimentation rate, and procalcitonin has been evaluated in the literature, but these tests do not have the needed sensitivity and specificity to definitively rule in a bacterial cause of fever. Blood cultures should be obtained in septic shock or if the results will change clinical management. Fever may not be always present in true infection, especially in elderly and immunocompromised patients. Oral temperatures suffer from poor sensitivity to diagnose fever, and core temperatures should be utilized if concern for fever is present. Consideration of non-infectious causes of elevated temperature is needed based on the clinical situation. Conclusion Any fever evaluation must rigorously maintain a broad differential to avoid pitfalls that can have patient care consequences. Fever is complex and due to a variety of etiologies. An understanding of the pathophysiology, causes, and assessment is important for emergency physicians.