Doctors use endoscopic ultrasound (EUS) to assess digestive (gastrointestinal) and lung diseases. This nonsurgical procedure uses high-frequency sound waves to produce detailed images of the lining and walls of the upper and lower digestive tract and nearby organs such as the pancreas, liver and gallbladder.

Endoscopic ultrasound is a minimally invasive procedure. Mayo Clinic has offered endoscopic ultrasounds since 1989, and doctors perform more than 3,000 each year.