Bilirubin excess, erythrophages and siderophages in differentiation of blood in cerebrospinal fluid.

Non-artificial blood admixture in cerebrospinal fluid (CSF) can be proven by demonstrating siderophages and 'bilirubin excess'. Bilirubin excess exists when the bilirubin concentration measured in the CSF exceeds the expected CSF bilirubin concentration. The expected CSF bilirubin concentration is calculated by multiplying the serum bilirubin concentration by the albumin quotient. Given a certain method of determination, a difference between the above-mentioned concentrations of less than 0.15 mumol/l must not be regarded as excess. Bilirubin excess was exclusively found in CSF with non-artificial blood admixture. Cytological and spectrophotometric studies are sufficient in screening for non-artificial blood admixture. When there are indications of an increased bilirubin concentration, calculations should be made in order to establish whether bilirubin excess exists. Lumbar puncture within 48 hours of the suspected haemorrhage should be avoided if possible.