Objective: The importance of lumbar puncture (LP) as part of the evaluation of suspected neonatal sepsis is assessed, as it may be the only positive diagnostic test in about 10% of septic babies with meningitis but negative blood cultures. However, LP may compromise respiratory function, and the interpretation of cerebrospinal fluid (CSF) may not be straightforward.
Conclusion: The clinical setting and the probability of meningitis are important determinants of the likely value of LP. For asymptomatic neonates with obstetric risk factors for sepsis, and for babies with early-onset respiratory distress alone, LP may be delayed and only performed later if blood cultures are positive. This is because hundreds of LP will be needed to diagnose a single case. However, infants with suspected late-onset sepsis should have an immediate LP because finding Gram-negative bacilli or fungi in the CSF will affect treatment choices.