Rapid diagnosis of infected ascitic fluid using leukocyte esterase dipstick testing.

Ascitic fluid infection is presumptively diagnosed when the fluid polymorphonuclear leukocyte (PMN) concentration equals or exceeds 250 cells/microl. The leukocyte esterase (LE) test has been shown to be a good predictor of the presence of PMNs and bacteria in urine and other body fluids. This study examines the value of the Multistix 10 SG LE Dipstick test for the rapid diagnosis of infected ascitic fluid. One hundred thirty-six ascitic fluid samples were evaluated by PMN count, culture, and LE Dipstick testing. LE dipstick values of "small" or greater were considered positive. For each sample, the LE test result was compared to the corresponding PMN count and culture result. Ten of the 11 LE-positive samples had PMN >/=250 cells/microl, while 10 of 12 samples with PMN >/=250 cells/microl were also LE-positive. Of the 125 LE-negative samples, 123 were also negative by PMN count. One hundred twenty-three of the 124 samples with PMN <250 cells/microl had negative LE tests. There was a less concordant relationship between the LE test and culture results. The sensitivity and specificity of the LE test for detecting ascitic fluid PMN >/=250 cells/microl were 83% and 99%, respectively, with a positive predictive value of 91% and a negative predictive value of 98%. The Multistix leukocyte esterase test is useful for the prompt detection of an elevated ascitic fluid PMN count, and represents a convenient new method for the rapid diagnosis of infected ascitic fluid.