,4 the technique of ERCP was described in detail in 1970 by Japanese endoscopists working with the Olympus and Machida companies.5 By 1974, independent groups in Germany and Japan had this website described endoscopic sphincterotomy as a treatment for bile duct stones.6,7 Five years later, Soehendra and Reynders-Frederix8 described the use of endoscopic biliary stents for the management of biliary obstruction. Although fiberoptic colonoscopes were available in 1970, the procedure was thought to be technically difficult in a similar way to ERCP. Because of this, the widespread acceptance of colonoscopy

was relatively slow despite the introduction of endoscopic polypectomy and the demonstration of superior diagnostic results when compared to barium enema studies.9 The next major development occurred in 1983 when Welch Allyn Inc. inserted an image sensor or charge-coupled device into the distal tip of an endoscope.10 Light is still transmitted down the H 89 in vitro endoscope through a fiberoptic bundle but the light falling on the charge-coupled device is converted into an array of electrical charges that are reconstructed on a video monitor. As solid-state sensors can only produce black and white images, modifications were required to reproduce the image in color. This was achieved by either the rapid sequential use of the primary colors, red, green

and blue, at the light source or by color-chip imaging where the solid-state sensor has colored microfilters bonded to its surface. By 1990, video endoscopy had largely replaced fiberoptic endoscopy, as the video image facilitated teaching and could be shared by other endoscopy staff. More recent developments include advances in EUS and the evolution of capsule endoscopy. Although the former was first described in 1976,11 EUS has had slow acceptance by gastroenterologists and even slower acceptance by non-gastroenterologists. Atezolizumab order Reasons for this include

the relatively high cost of equipment, the necessity for prolonged training and debate as to whether EUS provides useful additional information when compared to CT or MRI. However, the diagnostic role of EUS has now been firmly established with good results from fine-needle aspiration and cytological evaluation.12 Endoscopy using a swallowed capsule was first reported in 2000 by an Israeli company, Given Imaging.13 A complementary metal oxide silicon sensor uses much less power but provides an image quality that is similar to those of charge-coupled devices. Other innovative features include white-light-emitting diode illumination and miniaturisation of a video transmitter using UHF-band radio-telemetry to aerials strapped around the waist. Thus far, the capsule has been widely used for small bowel endoscopy but there are several other potential applications. These and other milestones in the evolution of endoscopy are summarized in Table 1. The gastrointestinal tract is a long tube that measures approximately 9 m in length from mouth to anus.