Paracentesis is a procedure in which a needle is inserted through the abdominal wall to remove fluid that has built up in the abdominal cavity (ascites). It may be used as a test (diagnostic paracentesis) or as a treatment (therapeutic paracentesis).

Paracentesis may be done to:

• Collect a fluid sample from the abdominal cavity to help find out the cause of ascites (diagnostic).
• Diagnose infection in the ascitic fluid (diagnostic).
• Remove a large amount of fluid from the abdominal cavity when the fluid is causing discomfort or affecting the function of the kidneys or intestines (therapeutic).