[Chemical and cytologic tests in the differential diagnosis of ascites]

The value of chemical (protein, LDH, glucose, total and differential cell count) and cytological examination of the ascitic fluid in the differential diagnosis of peritoneal ascites was assessed in a prospective study of 98 patients. The ascites caused by hepatic metastases and primary carcinoma were of the transudative type and could not be distinguished from the type caused by cirrhosis on the basis of the parameters examined. In contrast the ascites caused by peritoneal carcinosis was exudative presenting a highly significant (p less than 0.001 for all parameters) difference from the three preceding groups. However there was no clear-cut distinction between the groups: in fact cirrhosis patients may present exudative ascites (8% in the present series, 12-19% in the literature). There was a substantial decrease in ascitic fluid glucose (less than 60 mg/dl) only in peritonitis and its measurement is therefore of secondary importance. In contrast with reports by other authors the ratio between LDH and protein concentrations in the effusion and the serum was found to be insignificant. The cytological examination revealed a significantly higher total cell count in bacterial peritonitis with a prevalence of polymorphonuclear cells and in peritoneal carcinoma where mononuclear cells predominate. Finally cytology revealed malignant tumour cells in the ascitic fluid and neoplastic peritoneal effusions in 28% of the patients examined.