Pediatric Fever Workup: Age-Stratified Approach
The evaluation and management of a febrile child depends critically on age, with infants under 60 days requiring the most aggressive workup including blood, urine, and cerebrospinal fluid cultures, while older children can be risk-stratified based on clinical appearance and specific risk factors.
Infants 8-60 Days Old
This age group requires systematic evaluation for serious bacterial infection (SBI), with urinary tract infection being the most common culprit. 1
Immediate Assessment
- Measure rectal temperature to confirm fever ≥38.0°C (100.4°F) 1
- Assess for "toxic" appearance: altered mental status, severe lethargy, poor perfusion, respiratory distress, petechial/purpuric rash, or refusal to feed 2
- If oxygen saturation ≤92% or cyanosis present, immediate hospitalization with supplemental oxygen is mandatory 2
Diagnostic Workup for Well-Appearing Infants
Obtain urine specimen by catheterization or suprapubic aspiration (SPA) for urinalysis and culture 1. Bag collection is acceptable for initial urinalysis only—if positive, obtain catheterized specimen for culture 1. Circumcised boys have UTI likelihood <1% and may be exempted from routine urine testing 1.
Blood culture and complete blood count should be obtained 1.
Lumbar puncture is strongly recommended when:
- CSF is not obtained or uninterpretable, requiring hospitalization with experienced neonatal staff 1
- Any signs of meningismus, excessive somnolence, or systemic illness are present 3
Management Decisions
Hospitalize if: 1
- Infant appears ill or toxic
- Oxygen saturation ≤92%
- CSF not obtained or uninterpretable
- Positive blood or CSF cultures
Outpatient management acceptable if: 1
- Infant is well-appearing
- Normal CSF analysis obtained
- Reliable follow-up within 24 hours assured
- Parents understand return precautions
Discontinue antibiotics after 24-36 hours if: 1
- All cultures negative
- Infant clinically well or improving
- No other infection requiring treatment
Infants 2-24 Months Old
This age group can be risk-stratified, with UTI prevalence approximately 5% overall but varying significantly by sex, circumcision status, and other risk factors. 1
Risk Stratification for UTI
For girls, UTI probability <1% if no more than 1 risk factor present: 1
- White race
- Age <12 months
- Temperature ≥39°C
- Fever ≥2 days
- Absence of another infection source
For uncircumcised boys, UTI probability <1% with no more than 2 risk factors: 1
- Nonblack race
- Temperature ≥39°C
- Fever >24 hours
- Absence of another infection source
For circumcised boys, UTI probability <2% with no more than 3 risk factors 1
Diagnostic Approach
If low likelihood of UTI (criteria above met), clinical follow-up without testing is sufficient 1
If not low-risk, two options exist: 1
Option 1: Obtain catheterized or SPA urine for culture and urinalysis immediately 1
Option 2: Obtain convenient urine specimen for urinalysis first. If positive (leukocyte esterase, nitrite, leukocytes, or bacteria), then obtain catheterized/SPA specimen for culture. If fresh urine (<1 hour) urinalysis is negative for both leukocyte esterase and nitrite, monitoring without antibiotics is reasonable, though negative urinalysis does not completely rule out UTI 1
Critical Pitfall
Once antimicrobial therapy begins, the opportunity for definitive diagnosis is lost because urine sterilizes rapidly 1. Therefore, obtain proper culture specimens before starting antibiotics whenever possible.
Fever Management Across All Ages
The primary goal is improving the child's comfort, not normalizing temperature, as fever itself is a beneficial physiologic response that does not worsen illness outcomes or cause neurologic complications. 4
Antipyretic Use
Acetaminophen (paracetamol) is the antipyretic of choice 3, 4. Ibuprofen shows no substantial difference in safety or effectiveness compared to acetaminophen 4.
Antipyretics do NOT prevent febrile seizures or reduce recurrence risk 3, 5, 6. Their role is purely symptomatic relief 4.
Avoid combining acetaminophen and ibuprofen due to concerns about complicated dosing and unsafe use, despite evidence of greater effectiveness 4
Febrile Seizures (Ages 6-60 Months)
In infants <12 months with febrile seizure, lumbar puncture is almost always indicated to exclude meningitis 3.
For simple febrile seizures (brief, generalized, single episode in 24 hours), do NOT prescribe prophylactic anticonvulsants—risks outweigh benefits 5. The recurrence risk is approximately 30% overall (50% in infants <12 months), but >90% of children will not develop epilepsy 3, 5.
Neuroimaging is NOT indicated for simple febrile seizures 5. Consider imaging only for complex febrile seizures with focal neurologic deficits or suspected intracranial pathology 5.
Red Flags Requiring Immediate Referral
Refer urgently if any of the following present: 7
- Constantly irritable or inconsolable child
- Extremely lethargic, drowsy, or difficult to rouse
- Petechial or purpuric rash
- Respiratory distress or oxygen saturation ≤92%
- Poor perfusion or signs of shock
- Refusal to feed or signs of dehydration
- Neck stiffness or bulging fontanelle
Temperature measurement method matters—forehead thermometers may be inaccurate; rectal temperature is the gold standard in infants 7, 6, 8.