PWE-108 National survey of ascitic fluid wbc analysis method in the diagnosis of spontaneous bacterial peritonitis

Abstract

Introduction Spontaneous bacterial peritonitis (SBP) commonly found in patients with cirrhosis and ascites has significant mortality (10%) hence the need for prompt diagnosis and appropriate therapy. Diagnosis of SBP is based on neutrophil count1in ascitic fluid >250/mm3, traditionally measured manually; however there is excellent correlation between manual and automated counting methods.2Anecdotally, UK hospitals use both techniques. This national survey aims to establish which methods are used currently to diagnose SBP, its diagnostic criteria and limitations. Method UK Hospitals (n = 164) were invited to participate in a survey to establish the method used to quantify ascitic fluid WBC in diagnosis of SBP: manual cell count performed by microbiologist or fully automated cell count. They were asked also to comment on specific cut-off points used for diagnosis of SBP, the speed of analysis and any other comments. Results Results from eight national UK liver transplant centres suggested a lack of consistency, with 50% using manual cell count and the other 50% using automation. A similar pattern was seen nationally (n = 100), with 66% using a manual technique and 34% an automated method. Timely WBC counts were often not obtained manually eg results “within 18 h”, ”overnight”, ”four hours to get result”. In some cases, samples were sent by taxi to another hospital for manual analysis. In contrast, ascitic fluid WBC counts were generally obtained within 30–60 min utilising automated analysis. Nationally, lack of consensus was apparent in the cut-off used to diagnose SBP, with many hospitals using total WBC >250/mm3, rather than neutrophil count >250/mm3. In some hospitals, entirely different cut-offs were used, including: total WBC >500/mm3; 250 WBC/mm3or 150/mm3neutrophils; WBC >300/mm3; WBC >400/mm3or >250/mm3neutrophils. Some hospitals (n = 4) used additionally urine dipstick analysis of ascitic fluid. The cost of manual WBC ascitic fluid count is estimated at £16.83, whilst the cost of an automated count is £3.53, suggesting that nationally considerable cost savings could be made if all ascitic fluid samples are analysed in an automated way. Conclusion This national survey has highlighted the lack of consistency in the measurement of ascitic fluid WBC in the diagnosis of SBP across the UK, both in terms of method utilised and WBC cut-offs. Automated analysis produced faster results (<1 hr) and allowed differential WBC (incl neutrophil count) to be obtained readily. Widespread uptake of automated ascitic WBC measurement in conjunction with a clear WBC cut-off, as exemplified by use of the decompensated cirrhosis care bundle3is likely to improve patient care and outcomes. Disclosure of interest None Declared.