Low-protein-concentration ascitic fluid is predisposed to spontaneous bacterial peritonitis.

To assess the risk of development of spontaneous bacterial peritonitis in relation to the ascitic fluid total protein concentration, routine admission abdominal paracentesis was performed on a group of 107 patients during 125 hospitalizations. The paracentesis was repeated if evidence of peritonitis developed during hospitalization. Twenty-one episodes of spontaneous peritonitis (or its culture-negative variant) were documented in 17 patients. The ascitic fluid protein concentration in the spontaneous peritonitis group (0.72 +/- 0.53 g/dl) was significantly lower (p less than 0.001) than that in the group of patients with sterile portal hypertension-related ascites (1.36 +/- 0.89 g/dl) and was significantly lower than that of patients with ascites due to miscellaneous causes. Of the patients whose initial sterile ascitic fluid protein concentration was less than or equal to 1.0 g/dl, 7 of 47 (15%) developed spontaneous peritonitis during their hospitalization; whereas only 1 of 65 (1.5%) patients who had an initial sterile ascitic fluid protein concentration greater than 1.0 g/dl developed spontaneous peritonitis. This difference in risk of development of peritonitis in relation to initial ascitic fluid protein concentration was also significant (p less than 0.01). Low-protein-concentration ascitic fluid predisposes to spontaneous bacterial peritonitis.