Analysis of Cerebrospinal Fluid in the Neonate

NEONATES PRESENTING WITH apnea, seizures, signs and symptoms of infection or neurologic disorders often require evaluation of cerebrospinal fluid (CSF) as part of their diagnostic workup. Multiple studies can be done on CSF, including, but not limited to, evaluation of color, bacterial culture and Gram's stain, viral culture, cell count and differential, polymerase chain reaction (PCR), and quantitative determination of a number of laboratory values. Proper evaluation of CSF depends on knowing which tests to order, normal ranges for the patient's age, and the limitations of the test.¹ Reference ranges for CSF studies have been well established in the adult, but are not as well defined in the neonatal population.^2,3 This situation is further complicated by the vast differences between preterm and term infants. This column covers the interpretation of the most common tests done on CSF in the neonate. Many of the references cited are more than ten years old, but little new data support changes in the interpretation of neonatal CSF studies.