Evaluating the sensitivity of visual xanthochromia in patients with subarachnoid hemorrhage

Combined computed tomography and cerebrospinal fluid (CSF) analysis has been shown to be 100% sensitive for detecting subarachnoid hemorrhage (SAH) when CSF is obtained between 12 h and 2 weeks from time of headache onset and spectrophotometry is used to evaluate CSF for xanthochromia. Because most hospitals do not use spectrophotometry, we sought to evaluate the sensitivity of CSF analysis for xanthochromia by visual inspection. We retrospectively identified all patients seen in the Emergency Department (ED) with an ED discharge diagnosis of SAH from June 1993 to November 2005. A structured chart review was performed on all patients with the additional billed procedure charge for "lumbar puncture" or "spinal tap." Data collected included: CSF color, time from headache onset to CSF collection, and confirmation of SAH by advanced imaging. There were 1323 patients diagnosed with SAH, and 102 of these also had CSF collected. Of these, 81 charts were available for review. By predetermined protocol, 35 were excluded for lack of a report of CSF color, 1 was excluded because the time from headache onset to CSF collection was < 12 h, and 26 were excluded for lack of documentation of a definitive imaging study. Of the remaining 19, 9 were found to have xanthochromic CSF and 10 were found to have colorless CSF, resulting in a sensitivity for visual inspection of CSF of 47.3% (95% confidence interval 24.4-71.1%). Visual inspection of CSF supernatant for xanthochromia lacks the sensitivity necessary to reliably exclude the diagnosis of SAH.