The SAH diagnosis of choice is a computed tomography (CT) scan of the brain. The scan is accurate up to 12 hours after an SAH event in 98% of cases. During the first week following the SAH event, the diagnostic accuracy drops to 50%. To avoid false negatives and improve diagnostic accuracy, a control measurement is necessary. One possibility for improving diagnostic accuracy is by using spectrophotometric analysis of cerebrospinal fluid (CSF) as described in the “Revised national guidelines for analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage” a research article, first published in 2008 by Dr. Anne Cruickshank.