Gallbladder. Coloured ultrasound scan of a healthy gallbladder (black mass, centre right). The gallbladder stores and concentrates bile produced by the liver and secretes it into the small intestines where it helps the body to digest fat. Ultrasound is a diagnostic technique that sends high-frequency sound waves into the body via a transducer. The returning echoes are recorded and used to build an image of an internal structure.