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Interpretation of traumatic lumbar puncture. Predictive value in the presence of meningitis
Abstract:
Contamination of cerebrospinal fluid (CSF) with blood was studied prospectively in nine children with aseptic meningitis as the second phase of a study reported in this volume last month. Using criteria defined in the first phase, four of nine patients had recognizably abnormal CSF after experimental contamination with blood. As a third phase of the study, 53 children with bacterial meningitis were reviewed retrospectively to assess if hypothetical contamination of CSF with blood would have disguised their abnormal CSF studies. All but one of these 53 patients had either an abnormal CSF glucose or a positive gram stain (indicators independent of contamination with blood), and none would have gone undiagnosed with hypothetical contamination of up to 200,000 red cells per cubic millimeter. Guidelines for interpretation of laboratory studies following traumatic lumbar puncture are reviewed.
Insights
Blood contamination in cerebrospinal fluid (CSF) does not mask bacterial meningitis. Even with significant blood contamination, key diagnostic indicators like CSF glucose and gram stain remain reliable for diagnosing bacterial meningitis.
Area of Science:
- Pediatric infectious diseases
- Clinical pathology
- Cerebrospinal fluid analysis
Background:
- Cerebrospinal fluid (CSF) analysis is crucial for diagnosing meningitis.
- Accidental blood contamination during lumbar puncture can complicate CSF interpretation.
- Previous studies have explored the impact of blood contamination on CSF analysis.
Purpose of the Study:
- To evaluate the effect of blood contamination on CSF analysis in children with aseptic meningitis.
- To determine if blood contamination could obscure the diagnosis of bacterial meningitis in pediatric patients.
- To provide guidelines for interpreting CSF laboratory results after traumatic lumbar puncture.
Main Methods:
- Prospective study of 9 children with aseptic meningitis, experimentally contaminating CSF with blood.
- Retrospective review of 53 children with confirmed bacterial meningitis.
- Assessment of diagnostic indicators (CSF glucose, gram stain) under hypothetical blood contamination scenarios.
Main Results:
- In aseptic meningitis, 4 out of 9 patients showed abnormal CSF after experimental blood contamination.
- In bacterial meningitis, key indicators (CSF glucose, gram stain) were largely unaffected by hypothetical contamination up to 200,000 red cells/mm³.
- None of the bacterial meningitis cases would have been misdiagnosed due to blood contamination.
Conclusions:
- Blood contamination of CSF, even at significant levels, is unlikely to mask the diagnosis of bacterial meningitis.
- CSF glucose levels and gram stain results are robust indicators for bacterial meningitis diagnosis.
- Guidelines are provided for interpreting CSF laboratory studies following traumatic lumbar punctures.