Efficacy of Ascitic Fluid Dipstick Leukocyte Esterase Activity in Early Diagnosis of Spontaneous Bacterial Peritonitis

Abstract

Introduction: Spontaneously occurring ascitic fluid infections {Spontaneous Bacterial Peritonitis (SBP)} are the most common and recurring complications in patients with decompensated cirrhosis with ascitis. Unlike other infections, ascitic fluid infections usually present with non specific symptoms and may be asymptomatic in a large number of patients. They not only accelerate hepatic decompensation, but may also lead to, or exacerbate other complications like hepatic encephalopathy, hematemesis, renal failure and death. The existing protocol of diagnosis of SBP includes ascitic fluid total and differential leukocyte counts, and ascitic fluid cultures, by inoculating the ascitic fluid in blood culture vials, which are not only cumbersome, but also costly, time consuming and cannot be followed in all patients presenting for outpatient treatment for therapeutic peracentesis. Aim: To evaluate the efficacy of testing ascitic fluid pH, protein and Leucocyte Esterase (LERS) activity, by using Siemens Multistix 10SG Reagent Strips (SMRS) for early screening of patients for SBP. Materials and Methods: The observational study was conducted at SGRR Institute of Medical and Health Sciences Dehradun, Uttarakhand, India, from January 2018 to March 2019. The study included 329 patients with cirrhosis and ascites presenting in either the Outpatient Department (OPD) or Emergency Room for therapeutic paracentesis or with cirrhotic complications were evaluated for SBP using SMRS for ascitic fluid pH, Leukocyte Esterase (LERS) activity and ascitic fluid protein, for early detection of SBP. The standard diagnostic criteria i.e., ascitic fluid Polymorphonuclear Counts (PNM) more than 250 cells/mm3, by Chamber Counting Method or positive ascitic fluid culture after 48 hours incubation were used as gold standard for diagnosis of SBP. Chi-square test was applied to find out significant association between independent and dependent variables. A p-value of <0.05 was considered significant. Results: Among total 329 patients with cirrhotic ascitic, 81 were diagnosed to have SBP. At a cut-off of 2+, SMRS correctly detected SBP in 77/81 patients, was negative in 4/81 patients and falsely positive in 7/248 NSBP patients, thereby having a sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of 95%, 97.33%, 98.96% and 96.69%. At a cut-off of 3+, SMRS was able to detect SBP in 53/81 patients, and was falsely positive in 1/248 patients, thereby, although decreasing the sensitivity to 64%, but improving the specificity and PPV to 99.6% and 98.11%, respectively. Conclusion: During diagnostic paracentesis, ascitic fluid LERS activity using SMRS are highly sensitive markers for early detection of SBP, especially in the presence of fever, vomiting and shock.