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Gastrointestinal endoscopy has been attempted for >200 years, but the introduction of semirigid and flexible gastroscopes in the mid-twentieth century marked the dawn of the modern endoscopic era. Since then, rapid advances in endoscopic technology have led to dramatic changes in the diagnosis and treatment of many digestive diseases. Innovative endoscopic devices and new endoscopic treatment modalities continue to expand the use of endoscopy in patient care.
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Flexible endoscopes provide an electronic video image generated by a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) chip in the tip of the endoscope. Operator controls permit deflection of the endoscope tip; fiberoptic bundles or light-emitting diodes provide light at the tip of the endoscope; and working channels allow washing, suctioning, and the passage of instruments (Fig. 322-1). Progressive changes in the diameter and stiffness of endoscopes have improved the ease and patient tolerance of endoscopy. High-resolution and high-definition endoscopes equipped with electronic and optical magnification capabilities enable acquisition of images with a high level of detail. Advanced imaging techniques, including narrow-band imaging (Fig. 322-2) and real-time image-processing enhancement algorithms, aid in tissue characterization or differentiation.
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ENDOSCOPIC PROCEDURES
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Upper endoscopy, also referred to as esophagogastroduodenoscopy (EGD), is performed by passing a flexible endoscope through the mouth into the esophagus, stomach, and duodenum. The procedure is the best method for examining the upper gastrointestinal mucosa (Fig. 322-3). While the upper gastrointestinal radiographic series has similar accuracy for diagnosis of duodenal ulcer (Fig. 322-4), EGD is superior for detection of gastric ulcers (Fig. 322-5) and flat mucosal lesions, such as Barrett’s esophagus (Fig. 322-6), and it permits directed biopsy and endoscopic therapy. Intravenous sedation is given to most patients in the United States to ease the anxiety and discomfort of the procedure, although in many countries, EGD is routinely performed with topical pharyngeal anesthesia only. Patient tolerance of unsedated EGD is improved by the use of an ultrathin, 5-mm diameter endoscope that can be passed transorally or transnasally.
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