Percussion is a method of tapping body parts with fingers, hands, or small instruments as part of a physical examination. The purpose is to evaluate the size, consistency, borders, and presence or absence of fluid in body organs.

Percussion of a body part produces a sound -- like playing a drum -- that indicates the type of tissue within the organ:

• Lungs sound hollow on percussion because they are filled with air.
• Bones, joints, and solid organs such as the liver sound solid.
• The abdomen sounds like a hollow organ filled with air, fluid, or solids.