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Fever constitutes approximately 20% of visits to emergency departments nationwide. It is also the most common pediatric emergency concern. Fever is defined as body temperature greater than 38°C (100.4°F). Fever is induced by exogenous pyrogens from invading organisms and by endogenous pyrogens that are released by immune mediating cells to fight infectious pathogens. The pyrogens cause the body’s central “thermostat” in the hypothalamus to reset.

The majority of children presenting with fever will have benign causes and self-limited illness. The child’s parent may overtreat a fever or the physician may prescribe antibacterial therapy for a viral illness. Body temperature elevations alarm parents and caretakers, and may result in the child’s being brought for evaluation before a clinical syndrome can manifest itself. Fever can make a child uncomfortable, which can cause dehydration from insensible water loss.

The method of temperature measurement should be rectal in a child younger than 2 years as it is the most reliable means in this age group where detecting a fever is imperative. Oral temperatures are typically 1°C (1.8°F) lower and axillary 2°C (3.6°F) lower than rectal but should not be converted or substituted when a rectal measurement is indicated. Axillary temperatures are never appropriate in the emergency department. Tympanic and temporal thermometry are attractive as a less invasive technique but both are well studied to have demonstrated somewhat poor sensitivity for fever detection in pediatric patients.

Research regarding maternal tactile fever detection has shown the child’s mother to be accurate slightly greater than 50% of the time. This bears clinical consideration whereas nonvalidated fever is a not an uncommon complaint of emergency department pediatric illness. Excessive swaddling, environmental temperature, operator technique, digital versus mercury thermometer, type of device used, and consumption of liquids prior to oral measurements can affect measured temperatures.

Although most pediatric fever is caused by viral pathogens, the identification of cause of the fever as an invasive organism and/or a serious bacterial infection (SBI) is imperative to prevent morbidity or death in children. The younger the patient the less reliable the physical examination; infants younger than 3 months must be approached with utmost caution using appropriate clinical guidelines as serious bacterial illness is prevalent in that age group. However, all children younger than 3 years merit thorough evaluation.


General Considerations

Neonates are at high risk for SBI, the incidence of which is approximately 15-20%. Their immune systems are not fully developed, and clinical signs and findings are unreliable. The most common etiology of fever is viral, but group B streptococci, Escherichia coli, and Listeria monocytogenes are the most common causes of SBI.

Premature rupture of maternal membranes at delivery can be causative of early-onset neonatal sepsis, from days 1 to 8 of life, is usually caused ...

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