First used approximately 30 years ago, Endoscopic Ultrasound (EUS) has revolutionized the detection and treatment approach to both, lesions inside and outside the gastrointestinal tract, and opened the door for gastroenterologists and endoscopists to explore more. EUS is a minimally invasive procedure, performed both in an outpatient and inpatient basis, and can be used to assess digestive and lung diseases. Once a patient is under anesthesia, a thin, flexible endoscope with a small ultrasound probe at the tip of the scope, is passed through the mouth into the digestive tract. Using high-frequency ultrasound within the lumen of the gastrointestinal (GI) tract, one can not only obtain detailed images of the layers of the digestive tract but can also image nearby organs such as the liver, pancreas, lymph nodes and all the other surrounding structures. It not only allows for accurate local and regional staging of GI cancers such as esophageal, gastric, and rectal cancer but can also in diagnosing and staging of extraluminal cancers such as pancreatic and lung cancer.
In addition, EUS can visualize and drain any abnormal fluid collection such as a nearby abscess or a pancreatic fluid collection. Under ultrasound guidance, a fine needle can be passed through the wall of the GI tract to biopsy, aspirate, or inject any extraluminal structure. It can be done relatively safely under Doppler ultrasound to prevent bleeding complications. Through the years, EUS has also become a therapeutic procedure, especially for celiac plexus neurolysis, pseudocyst drainage, pancreaticogastrostomy, and other emerging treatments of pancreatic tumors, such as brachytherapy, gene, or cellular therapy. More recently, EUS has been used to gain access to closed lumens, such as bypassed gastric lumens or obstructed bile ducts. It would allow performing Endoscopic Retrograde Cholangiopancreatography in these patients without requiring an operation. EUS is also used to evaluate and stage other types of tumors seen on routine endoscopy, for example, carcinoid tumors, lipomas, stromal tumors, pancreatic rests, duplication cysts, and lipomas. One important example of this is in Barrett’s esophagus with high-grade dysplasia. EUS can accurately help stage this potentially malignant lesion before performing endoscopic mucosal resection, which In the past required surgery which had higher morbidity and mortality.
"EUS is a minimally invasive procedure, performed both in an outpatient and inpatient basis, and can be used to assess digestive and lung diseases"
Finally, EUS is a helpful tool to evaluate patients symptoms when other diagnostic tests have failed to reveal a diagnosis. For example, EUS is accurate in evaluating patients with symptoms arising from the bile duct or pancreas. As EUS technology continues to evolve, more indications will be added, which will help gastroenterologist diagnose and treat their patients better.