A high gap (> or=1.1 g/dL) indicates that ascites is due to portal hypertension with 97% accuracy. Increased hydrostatic pressure within the blood vessels of the hepatic portal system, results to force water out into the peritoneal cavity & leaves proteins such as albumin within the vasculature. The causes include Heart Failure, Budd Chiari syndrome & Liver Cirrhosis. A low gap (<1.1 g/dL) indicates that ascites is not associated with increased portal pressure, the causes include Nephritic syndrome, Tuberculosis and various types of malignancies.