1 Department of Pediatrics, University of Maryland Medical System, Baltimore, MD 21201
2 Department of Pediatrics, Johns Hopkins Bay View Medical Center, Baltimore, MD 21224
3 Department of Pediatrics, Temple University School of Medicine, St Christopher's Hospital for Children, Philadelphia, PA
Dr Scarano's point regarding potential bias introduced by red blood cells (RBCs) in the cerebrospinal fluid (CSF) is well taken. Review of the actual numbers of RBCs in the CSF shows that 50.5% of patients had <5 cells/mm3 and an additional 23.5% had <100 cells/mm3 and only 4.2% had >500 cells/mm3. We excluded all patients with "bloody taps," which we defined as >1000 RBCs/mm3 in the CSF. Since the majority of patients had less than 100 RBCs in their CSF, we feel that the potential for bias resulting from blood contamination of the CSF is minimal.