Is a lumbar puncture necessary when evaluating febrile infants (30 to 90 days of age) with an abnormal urinalysis?

OBJECTIVES

Guidelines for the management of febrile infants aged 30 to 90 days presenting to the emergency department (ED) suggest that a lumbar puncture (LP) should be performed routinely if a positive urinalysis is found during initial investigations. The aim of our study was to assess the necessity of routine LPs in infants aged 30 to 90 days presenting to the ED for a fever without source but are found to have a positive urine analysis.

METHODS

We retrospectively reviewed the records of all infants aged 30 to 90 days, presenting to the Montreal Children's Hospital ED from October 2001 to August 2005 who underwent an LP for bacterial culture, in addition to urinalysis and blood and urine cultures. Descriptive statistics and their corresponding confidence intervals were used.

RESULTS

Overall, 392 infants were identified using the microbiology laboratory database. Fifty-seven patients had an abnormal urinalysis. Of these, 1 infant (71 days old) had an Escherichia coli urinary tract infection, bacteremia, and meningitis. This patient, however, was not well on history, and the peripheral white blood cell count was low at 2.9 × 10⁹/L. Thus, the negative predictive value of an abnormal urinalysis for meningitis was 98.2%.

CONCLUSIONS

Routine LPs are not required in infants (30-90 days) presenting to the ED with a fever and a positive urinalysis if they are considered at low risk for serious bacterial infection based on clinical and laboratory criteria. However, we recommend that judicious clinical judgment be used; in doubt, an LP should be performed before empiric antibiotic therapy is begun.