Comparison of original (2003) and revised (2008) national guidelines for reporting of cerebrospinal fluid spectrophotometric scanning for suspected subarachnoid haemorrhage against patient outcome

Abstract

National guidelines for cerebrospinal fluid (CSF) analysis and its reporting in suspected subarachnoid haemorrhage (SAH) were published in 2003, but revised in 2008 to give greater clarity in interpretation. It is not known whether the less ambiguous reporting of 2008 guidelines may lead to a false assurance and adversely affect patient outcome. We, therefore, re-interpreted scans reported under the 2003 guidelines, using the 2008 guidelines and compared these reports against final diagnosis and patient outcome obtained from a retrospective case-note review audit. We identified requests for CSF xanthochromia studies from the laboratory system between September 2006 and August 2007. Spectroscopy scans were then retrieved and re-interpreted using the 2008 guidelines. The original reports and re-interpreted scans were compared against diagnosis and patient outcome using case-note review. We received 93 requests for CSF spectroscopy on 90 patients. Fourteen requests were not processed due to insufficient sample, but of these three patients had a repeat lumbar puncture (LP). Two further requests were not processed at the request of the clinician as they were no longer clinically indicated. Therefore, 77 spectroscopic scans were re-interpreted. The revised guidelines re-classified 11 previously equivocal scans into the not supportive of SAH category. On case-note review, one patient had a subsequent fatal SAH. The remaining 10 were given non-SAH final diagnoses and none had similar further inpatient episodes for at least 12 months and up to 18 months following LP. The revised (2008) national guidelines for the analysis of CSF in suspected SAH offer greater clarity in reporting without adversely affecting patient outcome.