Procedural Ultrasound

Thoracentesis & Paracentesis


  • Ultrasound quantifies better than CXR
  • Can identify complex/ loculated effusions
  • Can estimate volume
  • May substantially reduce incidence of pneumothorax
  • Static technique acceptable
thoracentesis sensor position


So thoracentesis and paracentesis are two procedures where you are typically accessing a fairly large volume of fluid in a particular body cavity. In this case, a static technique may be appropriate, where you find the area where the pocket of fluid is closest to the skin, you mark it using indentation or a skin marking pen, put down the probe, make it sterile, and then access that fluid filled volume. So for thoracentesis, ultrasound has some particular advantages. It can quantify fluid certainly better than chest x-ray and often better than CT scan. It can also identify complex or loculated effusions that are difficult to tap, it can estimate the volume, and there is evidence to show that using it appropriately will decrease the incidence of pneumothorax. So when you are doing this you may again find the pocket of fluid, identify the diaphragm.

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