title: Interpretation of Cerebrospinal Fluid White Blood Cell Counts in Young Infants With a Traumatic Lumbar Puncture.
abstract: OBJECTIVE
  We determine the optimal correction factor for cerebrospinal fluid WBC counts in infants with traumatic lumbar punctures.
  
  
  METHODS
  We performed a secondary analysis of a retrospective cohort of infants aged 60 days or younger and with a traumatic lumbar puncture (cerebrospinal fluid RBC count ≥10,000 cells/mm3) at 20 participating centers. Cerebrospinal fluid pleocytosis was defined as a cerebrospinal fluid WBC count greater than or equal to 20 cells/mm3for infants aged 28 days or younger and greater than or equal to 10 cells/mm3for infants aged 29 to 60 days; bacterial meningitis was defined as growth of pathogenic bacteria from cerebrospinal fluid culture. Using linear regression, we derived a cerebrospinal fluid WBC correction factor and compared the uncorrected with the corrected cerebrospinal fluid WBC count for the detection of bacterial meningitis.
  
  
  RESULTS
  Of the eligible 20,319 lumbar punctures, 2,880 (14%) were traumatic, and 33 of these patients (1.1%) had bacterial meningitis. The derived cerebrospinal fluid RBCs:WBCs ratio was 877:1 (95% confidence interval [CI] 805 to 961:1). Compared with the uncorrected cerebrospinal fluid WBC count, the corrected one had lower sensitivity for bacterial meningitis (88% uncorrected versus 67% corrected; difference 21%; 95% CI 10% to 37%) but resulted in fewer infants with cerebrospinal fluid pleocytosis (78% uncorrected versus 33% corrected; difference 45%; 95% CI 43% to 47%). Cerebrospinal fluid WBC count correction resulted in the misclassification of 7 additional infants with bacterial meningitis, who were misclassified as not having cerebrospinal fluid pleocytosis; only 1 of these infants was older than 28 days.
  
  
  CONCLUSIONS
  Correction of the cerebrospinal fluid WBC count substantially reduced the number of infants with cerebrospinal fluid pleocytosis while misclassifying only 1 infant with bacterial meningitis of those aged 29 to 60 days.
authors.affiliation: Division of Emergency Medicine, Boston Children's Hospital, Boston, MA.
authors.forename: Todd W
authors.initials: TW
authors.lastname: Lyons
authors.affiliation: Sections of Pediatric Emergency Medicine and Pediatric Infectious Diseases, Baylor College of Medicine, Houston, TX.
authors.forename: Andrea T
authors.initials: AT
authors.lastname: Cruz
authors.affiliation: Sections of Pediatric Emergency Medicine and Gastroenterology, Alberta Children's Hospital, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Freedman
authors.affiliation: Division of Emergency Medicine, Boston Children's Hospital, Boston, MA.
authors.forename: Mark I
authors.initials: MI
authors.lastname: Neuman
authors.affiliation: Division of Emergency Medicine, Children's Hospital of Philadelphia, Philadelphia, PA.
authors.forename: Fran
authors.initials: F
authors.lastname: Balamuth
authors.affiliation: Pediatric Emergency Medicine Department, University of Colorado Hospital/Children's Hospital Colorado, Aurora, CO.
authors.forename: Rakesh D
authors.initials: RD
authors.lastname: Mistry
authors.affiliation: Division of Pediatric Emergency Medicine, Children's Hospital of Michigan, Detroit, MI.
authors.forename: Prashant
authors.initials: P
authors.lastname: Mahajan
authors.affiliation: Departments of Pediatrics and Emergency Medicine, Yale School of Medicine, New Haven, CT.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Aronson
authors.affiliation: Division of Hospital Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
authors.forename: Joanna E
authors.initials: JE
authors.lastname: Thomson
authors.affiliation: Division of Pediatric Emergency Medicine, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Pruitt
authors.affiliation: Division of Hospital Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
authors.forename: Samir S
authors.initials: SS
authors.lastname: Shah
authors.affiliation: Division of Emergency Medicine, Boston Children's Hospital, Boston, MA. Electronic address: lise.nigrovic@childrens.harvard.edu.
authors.forename: Lise E
authors.initials: LE
authors.lastname: Nigrovic
mesh_terms: D016470:Bacteremia / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000382:microbiology; D002555:Cerebrospinal Fluid / Q000166:cytology*; D005260:Female; D006561:Herpes Simplex / Q000134:cerebrospinal fluid / Q000175:diagnosis; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007958:Leukocyte Count; D008297:Male; D016920:Meningitis, Bacterial / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000382:microbiology; D012189:Retrospective Studies; D013129:Spinal Puncture / Q000009:adverse effects / Q000379:methods; D014552:Urinary Tract Infections / Q000134:cerebrospinal fluid / Q000175:diagnosis / Q000382:microbiology