CSF xanthochromia analysis takes longer following centralisation of the laboratories testing samples – how can we improve the time to result?

Lumbar puncture is an essential tool for excluding subarachnoid haemorrhage. In August 2012, the laboratory at which cerebrospinal fluid (CSF) is analysed for xanthochromia in Lanarkshire was centralised at Hairmyres (East Kilbride, UK). Prior to this, each of the three hospitals analysed their own specimens. We aim to assess whether or not the change in xanthochromia processing has resulted in diagnostic delay at Wishaw General Hospital in the assessment of CT negative possible subarachnoid haemorrhage. We subsequently assessed the impact of a strategy to minimise any delay, i.e. increasing laboratory processing hours. Patients undergoing CSF analysis for xanthochromia were identified directly from the laboratory database. Time of lumbar puncture, and time of xanthochromia results were obtained from the hospital's laboratory computer system. Data were analysed using a commercially available statistical software programme (Microsoft Excel). Audit was repeated after the change to a centralised laboratory, and again following the increased laboratory working hours. Mean time from lumbar puncture to availability of xanthochromia result was significantly longer following the laboratory change (20.8±3.5 hours post [n=35] vs. 12.5±3.0 pre, p=0.01 [n=17]). However, following a change in the laboratory's practice, there was no improvement (19.8±3.4 hours post practice change [n=35]), and this remained significantly longer when compared to the original laboratory set-up (p=0.025). The change in laboratory processing CSF samples for xanthochromia in Lanarkshire resulted in a significant delay in analysing the samples. Attempts by the laboratory to extend processing hours did not make any significant improvement, but having expanded our knowledge of the issues, further measures are now planned to minimise delays in the future. Centralisation of laboratory services for CSF analysis, whilst cheaper, may impact negatively on clinical care.