Value of Quantitative Cell Count and Amylase Activity of Peritoneal Lavage Fluid

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Abstract
From Jan. 1974 through July 1979, 1588 patients underwent diagnostic peritoneal lavage. The test had an accuracy of 98.6%, sensitivity of 94.3% and specificity of 99.8%. It was true positive in 21.9%, false positive in 0.1%, false negative in 1.3% and true negative in 76.6%. Patients (59) from the true-positive group had grossly equivocal tests, but had positive lavage results based on quantitative cell count. Without cell count the test would have a sensitivity of 78.3%, accuracy of 94.8% and specificity of 99.8%. Patients (8) had positive lavage based on WBC [white blood cell] count but negative RBC [red blood cell] count; all of these patients had bowel injuries. Measurement of lavage fluid amylase resulted in minimal or no improvement in the accuracy (0.06%), sensitivity (0.3%), or specificity (0.0%). Of 6 patients 5 with positive amylase levels but grossly negative tests had concomitant positive WBC count. The added cost of the amylase measurement is estimated to be $154,472. Peritoneal lavage has high accuracy, sensitivity and specificity. Cell counts significantly improve sensitivity. Patients with a grossly equivocal test but with a positive cell count should undergo laparotomy. The lavage-fluid amylase measurement is costly and is of insignificant yield.