Pericardiocentesis

This illustration shows pericardiocentesis, which is a medical procedure that is performed when fluid accumulates in the sac surrounding the heart (pericardium). A pericardial effusion is the medical term for the presence of fluid within the pericardium. A needle (often guided by an x-ray or ultrasound) is inserted into the pericardium to relieve pressure on the heart and/or to collect fluid to help diagnose the cause of fluid accumulation (such as infection, inflammation, or cancer).