Over the past several decades, flexible endoscopy has shifted the management of numerous gastrointestinal diseases from the surgeon to the endoscopist. What had started as a diagnostic discipline has now become one of advanced therapeutic potential. The concept of performing endoscopic surgery has become a reality with the advancement of endoluminal therapies for neoplasia, gastroesophageal reflux, and obesity. In addition, with the significant investigation into natural orifice translumenal endoscopic surgery (NOTES) and the development of advanced endoscopic tools, the ability to perform intraperitoneal therapies without abdominal scars continues to become more possible. This chapter will address the indications and techniques for upper and lower flexible endoscopy as well as the recent advances in imaging and interventional endoscopy.
The flexible endoscope was initially developed in 1957 as an imaging device dependent on the delivery of light and transmission of the image along multiple bundles of chemically treated glass fibers. The fiberoptic bundle is 2–3 mm wide and is composed of 20,000–40,000 individual fine glass fibers, each approximately 10 μm in diameter.1 The image undergoes a series of internal reflections within each fiber, which are coated with low optical density glass to prevent escape of light, as it is transmitted up the bundle. Due to formation of the fibers and surrounding material, a characteristic meshed image is seen in fiberoptic endoscopes, which inherently results in a lower resolution than that seen with rigid lens systems. In addition, if the fibers become cracked, the image is not generated at this site of the bundle and multiple black spots are seen.
When utilizing a fiberoptic endoscope, the endoscopist views the image through the eyepiece at the instrument head, or alternatively, a video camera can be affixed to the eyepiece to transmit the image to a video monitor. The progression from fiberoptic scopes to the videoendoscopes, we use today, has allowed for advancements in our ability to perform more involved therapies, educate physicians and endoscopic assistants, and obtain static and dynamic recorded data images for improved clinical management.
The majority of endoscopes in use today are videoscopic, although in many parts of the world, fiberoptic systems are still the standard. In these videoscopic systems, the visualized image is created from reflections onto a charge coupled device (CCD), which is a chip mounted at the end of the endoscope rather than via the fiberoptic bundles. The CCD chip has thousands of pixels (light-sensitive points), which directly increase image resolution.2
There have been many recent advances in endoscopic imaging techniques. The purpose of most of these techniques is early detection of dysplasia, which might elude standard endoscopic visualization. Clinical use of new imaging is limited principally to specialized centers, but future widespread application of an imaging method for early dysplasia detection is a certainty.
The aim of chromoendoscopy ...