Endoscopic ultrasonography of the upper gastrointestinal tract.

Endoscopic ultrasonography combines the advantages of conventional endoscopy with the capabilities of ultrasonography. This permits the examiner to see through the wall of the gastrointestinal tract. The close proximity permits the use of relatively high frequencies, with the resulting increase in tissue contrast and resolution. There are limitations to its use, however, with the main one being a field of view limited to a 7-cm radius. Discussed in this article is its use for the gastrointestinal wall, the esophagus, the stomach, the duodenum, and the pancreas.