Guidelines for endoscopic ultrasonography.

Introduction This guideline addresses the use of endoscopic ultrasound (EUS) as part of the diagnostic evaluation of certain conditions. In addition, issues of training and credentialing in EUS and complications of this procedure are also dealt with, within these guidelines. EUS combines features of endoscopy and ultrasonography in order to obtain structural information about organs within and without the gastrointestinal tract. This is accomplished through the use of a scanning transducer, which is built into the distal tip of the endoscope. The technique originated just after the Second World War when newly obsolete naval ultrasound equipment became available. Wild and Reid modifi ed the equipment and developed a mechanical ultrasound transducer which they inserted into the rectum of several healthy volunteers in order to obtain endoluminal ultrasound images of the rectal wall. The upper gastrointestinal tract was fi rst examined by Rasmussen and colleagues who passed the ultrasound catheter probe down the biopsy channel of an early endoscope and measured the thickness of the gastric wall. EUS became a useful clinical tool in the early 1980s with the development of dedicated endoscopes. They were initially used for diagnostic procedures of upper gastrointestinal tract with circumferential overview of the gastrointestinal wall and its surroundings. Some 10 years later, longitudinal or linear electronic scanners were developed which allow biopsies and other interventions.1,2 Subsequent technological improvements such as the ability to perform EUS-guided fi ne needle aspiration (EUSFNA), EUS-guided injection and EUS-guided endoscopic drainage have increased the diagnostic and therapeutic potential of this procedure. Endoscopic ultrasonography is available in all the major public and private hospitals in Singapore. As the number of EUS practitioners increases yearly, a group of experienced EUS gastroenterologists under the auspices of the Academy of Medicine, Singapore decided to come together to formulate a guideline on the training, credentialing and performing quality control of this procedure. This document is formulated based on the scientifi c evidence available and where there is a lack of such data, decisions are made on the basis of expert opinion from the working group.