Although conventional esophagogastroduodenoscopy has become widespread in its applications and availability, it is constrained by the requirement for patient sedation. This requirement contributes to morbidity, time lost from work, and additional resource utilization in personnel and facilities. Small-caliber endoscopy is an emerging technology that enables transnasal evaluation of the upper gastrointestinal tract in a unsedated patient. This procedure can be performed in a wider range of settings, including the clinic setting where a dedicated conscious sedation suite is not available and can be incorporated into the office visit. The applications of small-caliber endoscopy include general diagnostic upper endoscopy, screening and surveillance of Barrett esophagus, and intraoperative diagnostics or postoperative evaluation of the upper gastrointestinal tract. Therapeutic applications include the placement of nasoduodenal feeding tubes, esophageal pH catheters, and impedance catheters. When used in the sedated patient, small-caliber endoscopy can also facilitate esophageal stricture dilation and transnasal placement of a percutaneous endoscopic gastrostomy tube. This review discusses the techniques, equipment, and applications of small-caliber endoscopy of the upper gastrointestinal tract.
