Peritoneal fluid

• When you have abdominal pain and swelling, nausea, and/or fever and your healthcare practitioner suspects you have peritonitis or ascites.
• A sample of peritoneal fluid is collected by a healthcare practitioner with a syringe and needle using a procedure called paracentesis. 
• To help diagnose the cause of peritonitis, an inflammation of the membrane lining the abdomen, and/or peritoneal fluid accumulation, where fluid builds up in the abdomen or around internal organs (called ascites)