A peritoneal ascitic fluid analysis, also called a peritoneal fluid analysis, is a laboratory test that examines fluid that has accumulated in the abdominal cavity (ascites) to determine the cause of this fluid buildup, often by analyzing its cell count, protein levels, and appearance, which can help diagnose conditions like liver cirrhosis, cancer, or infection within the abdomen; the fluid is obtained through a procedure called paracentesis, where a needle is inserted into the abdominal cavity to extract a sample.