Although most neonates and young infants with fever have a benign viral illness, the goal of the evaluation is to identify those children who are at high risk for serious bacterial illness (eg, bacteremia, urinary tract infection, meningitis, bacterial gastroenteritis, pneumonia), and who therefore require empiric antimicrobial therapy and possibly hospitalization.
The young febrile infant may demonstrate few, if any, interpretable clues to the underlying illness . The limitations of the history and physical examination in neonates and young infants with fever traditionally have led to an aggressive laboratory evaluation, even for patients who were previously healthy, are well-appearing, and have no focal infection. In addition, most of the patients have been admitted to the hospital for antibiotic treatment pending negative cultures. This practice is expensive and can result in iatrogenic morbidity for a substantial number of infants .
The evaluation of neonates and young infants younger than three months with fever is discussed below. The definition and etiology of fever in this age group, as well as traditional strategies for evaluating young infants with fever, are discussed separately. (See "Definition and etiology of fever in neonates and infants (less than three months of age)" and "Strategies for the evaluation of fever in neonates and infants (less than three months of age)".)
The evaluation of infants and children age 3 to 36 months is discussed separately. In addition, the diagnosis and treatment of specific infections, including meningitis, pneumonia, and urinary tract infections, is discussed elsewhere. (See "Fever without a source in children 3 to 36 months of age" and "Clinical features and diagnosis of acute bacterial meningitis in children older than one month of age" and "Clinical features and diagnosis of community-acquired pneumonia in children" and "Urinary tract infections in newborns".)
A thorough history is an essential component of the evaluation of all neonates and young infants with fever (T ≥38ºC or 100.4ºF). The history should address the following clues to the etiology of the fever: