The serum-ascites albumin gradient (SAAG) is the most useful index for evaluating peritoneal fluid and can help distinguish ascites caused by portal hypertension (cirrhosis, portal vein thrombosis, Budd-Chiari syndrome, etc.)
SAAG is calculated by subtracting the albumin measure of ascitic fluid from the serum value.
Peritoneal fluid microscopy is a useful test in evaluating the cause of ascites.
A diagnostic peritoneal lavage (DPL) is considered positive if any of the following are present [1] Bacteria and white blood cells, when present in a patient with a history of ascites (usually due to cirrhosis) is highly suggestive of spontaneous bacterial peritonitis.
This article incorporates public domain material from Dictionary of Cancer Terms.