1. The surgical puncture of the abdominal cavity for the removal of fluid for diagnosis or treatment: Joan had to go to the hospital to have an abdominal paracentesis performed because she had excess liquid in the visceral area.
2. A puncture of the wall of a fluid-filled cavity with a hollow needle to draw off the contents for medical diagnosis: A trocar is used during an abdominal paracentesis to obtain some ascitic fluid for examination from a patient while he or she is in a sitting position.