Things We Do for No Reason™: Lumbar Punctures in Low-Risk Febrile Infants with Bronchiolitis

A 22-day-old full-term previously healthy male infant was evaluated in the emergency department (ED). The patient’s mother reported a three-day history of nasal congestion, cough and labored breathing, decreased oral intake, and subjective fever.

In the ED, the patient was found to have a rectal temperature of 101.3 °F (38.3 °C), heart rate of 112 beats per minute, and a respiratory rate of 54 breaths per minute, with subcostal retractions and diffuse expiratory wheezing. His appearance was otherwise unremarkable. His evaluation in the ED included a normal complete blood count (CBC) with differential, a normal urinalysis, and a chest radiograph with diffuse peribronchial thickening. Blood and catheterized urine cultures were also collected. The patient’s provider informs the parents that a lumbar puncture (LP) would be performed to rule out bacterial meningitis. Is it necessary for this patient to receive an LP?

Fever in an infant <90 days old is a common clinical presentation.¹ Because a newborn’s immune system is still developing, there is a heightened concern for bacterial infections in this age group. These include bloodstream infections, meningitis, pneumonia, urinary tract infections (UTIs), skin/soft tissue infections, and osteoarticular infections. Bacterial infections collectively account for approximately 10% of illness in young febrile infants <90 days.² Of these, UTIs are the most common. The most recent literature has narrowed the focus on infants <60 days old as the risk of serious infection is inversely correlated with age. Meningitis accounts for 1% of infections or less in children <60 days of age who present with a fever.³

Frequently, the evaluation of fever in young infants leads to cerebrospinal fluid (CSF) collection and hospitalization.⁴ Among febrile infants, current practice patterns regarding LPs vary across institutions.⁵ Some clinical practice guidelines recommend universal CSF testing for all febrile infants ≤56 days old.⁶

Bronchiolitis is also a common presentation. Up to 90% of children are infected with respiratory syncytial virus, the most common viral cause of bronchiolitis, within the first two years of life.⁷ Fever may be a presenting symptom in infants with bronchiolitis and one study found approximately 11% of febrile infants less than 90 days old met clinical criteria for bronchiolitis.⁸