title: Value of quantitative cell count and amylase activity of peritoneal lavage fluid.
abstract: From January 1974 through July 1979, 1,588 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%. Fifty-nine patients from the true-positive group had grossly equivocal tests, but had positive lavage results based on quantitative cell count. Thus without cell count the test would have a sensitivity of 78.3%, accuracy of 94.8%, and specificity of 99.8. Eight patients had positive lavage based on WBC count but negative RBC 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%). Five of six patients 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 insignificantly yield.
mesh_terms: D000007:Abdominal Injuries / Q000175:diagnosis* / Q000201:enzymology; D000681:Amylases / Q000032:analysis*; D001202:Ascitic Fluid / Q000166:cytology* / Q000201:enzymology; D004796:Clinical Enzyme Tests; D004906:Erythrocyte Count; D006801:Humans; D007958:Leukocyte Count; D007507:Therapeutic Irrigation; D014949:Wounds, Nonpenetrating / Q000175:diagnosis
chemical_list: D000681:Amylases