What represents pleocytosis in blood-contaminated (“traumatic tap”) cerebrospinal fluid in children?

Abstract

THE NUMBER of white blood cells normally present in cerebrospinal fluid after a nontraumatic lumbar puncture has been clearly established? ~2 Although the number of WBCs in CSF contaminated with blood has not been studied systematically, suggested definitions for normal values include a comparable WBC/RBC ratio in CSF and in peripheral blood ~ or the use of an arbitrary WBC/RBC ratio of 1:300. 4 Both of these definitions imply that when CSF is contaminated with blood there exists a fixed relationship between the number of RBCs and WBCs in CSF and peripheral blood, in the absence of preexisting CSF pleocytosis. Two recent analyses of blood-stained CSF specimens obtained from a small number of patients without meningitis demonstrated fewer WBCs than expected from calculation of the peripheral blood WBC/RBC ratio. ~,6 This observation suggests that current definitions might well obscure the detection of true CSF pleocytosis in such specimens, The purpose of our study was to analyze a larger number of blood-contaminated CSF samples in order to define better the relationship between the number of WBCs present and the expected number calculated from peripheral blood RBC and WBC counts. METHODS We performed a retrospective analysis of the CSF data of all patients at The Children's Memorial Hospital during 1983 whose CSF samples contained > 1000 RBC/mm 3 and in whom a complete blood count was performed simultaneously with or within 2 hours of lumbar puncture. CSF cell counts were done routinely using the standard counting chamber and acetic acid lysis technique described by Hepler. 7 CSF samples obtained by a neurosurgical procedure or with positive bacteriologic culture not judged to be a contaminant were excluded. Because it had been suggest