Figure 1.

Diagnostic algorithm for new onset ascites. Among the additional tests on ascitic fluid, low glucose levels are associated with tuberculosis or peritoneal carcinomatosis and bacterial peritonitis. High concentrations of lactic dehydrogenase (LDH) should lead to the suspicion of a non-hepatic cause, in particular a malignant etiology, peritonitis secondary to intestinal perforation, acute pancreatitis, and tuberculous peritonitis. The combined determination of total proteins, glucose, and LDH has also been proposed to differentiate forms of spontaneous from secondary bacterial peritonitis (proteins > 1 g/dL, glucose <50 mg/dL, high LDH). High levels of amylase can be found in pancreatic ascites or intestinal perforation, ischemia, and mesenteric thrombosis, whereas the dosages of creatinine and bilirubin are useful in the suspicion presence of urine and biliary or intestinal perforation respectively. Opalescent ascitic fluid would require the dosage of triglycerides, as levels higher than 200 mg/dL indicate chylous ascites. An activity of the adenosine-deaminase enzyme (ADA) greater than 39 IU/L suggests the diagnosis of tuberculous ascites, although this dosage is only useful in areas with high prevalence and in the absence of liver cirrhosis.⁶ CT: computed-tomography; MR: magnetic resonance.