In a two-year period, ascitic fluid concentrations of
complement 3c and
complement 4 were measured in 110 patients with sterile cirrhotic
ascites, 31 patients with spontaneous bacterial
peritonitis, 65 patients with
hepatocellular carcinoma, 36 patients with
peritoneal carcinomatosis and 12 patients with miscellaneous diseases (
nephrotic syndrome 4,
systemic lupus erythematosus 3,
secondary peritonitis 2, cardiac
ascites 1, eosinophilic
peritonitis 1 and
tuberculosis peritonitis 1) to assess the clinical utility of ascitic fluid complements. The ascitic fluid level of complements 3c or C4 was significantly higher in patients with
peritoneal carcinomatosis (32.8 +/- 10.2, 13.4 +/- 7.4 mg/dL) than in patients with sterile cirrhotic
ascites (9.2 +/- 5.2, 4.5 +/- 3.9 mg/dL, p < 0.001), spontaneous bacterial
peritonitis (8.2 +/- 4.1, 3.8 +/- 2.4 mg/dL, p < 0.001) or
hepatocellular carcinoma (12.8 +/- 8.3, 5.6 +/- 4.4 mg/dL, p < 0.001). However, it was not significantly different from the miscellaneous disease group. To verify that
ascites formation is not related to
liver disease origin, diagnostic sensitivity, specificity and accuracy were 83.3%, 92.7% and 90.9%, respectively, by the ascitic fluid level of
complement 3c higher than the cut-off value (20 mg/dl); or 60.4%, 89.8% and 84.3%, respectively, by the ascitic fluid level of
complement 4 higher than the cut-off value (10 mg/dL). A direct correlation was found between the ascitic fluid
protein level and the ascitic fluid
complement 3c (r = 0.70) or
complement 4 (r = 0.57) level. Based on results in this study, we can conclude that measuring ascitic fluid complements is clinically useful in disapproving the
liver disease origin of
ascites formation. However, it is of little value in diagnosing spontaneous bacterial
peritonitis or
hepatocellular carcinoma.