The development of colonoscopy would largely not be possible were it not for technologic advances in upper gastrointestinal endoscopy. Therefore, noteworthy breakthroughs will be reviewed here. Early endoscopic advances were largely modifications of instruments based on Bozzini’s Lichtleiter. John Fisher in the United States and Segales in France illuminated body cavities using a system of mirrors to reflect candlelight [5]. In 1824 Fisher added a double convex lens to sharpen and enlarge the viewed image [6]. Antonin Desormeaux is credited with developing the first open-tube endoscope [5, 6]. He used a lamp fueled by a combination of alcohol and turpentine for continuous illumination. Another significant advance was the use of a condenser lens to concentrate the illumination on a single spot [7]. However, a significant drawback of this system was the thermal tissue injuries from the heat created by the light source.

In 1877 Maximilian Nitze introduced his cystoscope, which is often considered the first practical endoscopic instrument (Fig. 1.2). He used a platinum wire loop lamp with a water cooling system for illumination [6]. Significant advances he incorporated were placing the light source at the tip of the instrument to improve illumination and enlarging the field of view by using an optical system [8]. After Thomas Edison’s invention of incandescent light in 1879, Nitze incorporated a miniaturized version of the filament globe into his device.

Edison’s invention proved significant for the future of endoscopes, as the use of incandescent light eliminated the need for the then-used platinum loop lamp and its unwieldy cooling system. Johann von Mikulicz and Josef Leiter in 1881 introduced an esophagoscope that consisted of a straight tube with a small bulb at the distal end of the instrument [6]. Mikulicz also added to Nitze’s model by adding a mirror to create an angular field and an air canal to allow for insufflation [7]. The result of this combination was a greater field of view to examine otherwise collapsed cavities. Six years later Leiter produced what he called the panelectroscope. By reflecting light from an electric lamp built into the handle, the panelectroscope served as a universal light source for all endoscopic tools.

The next series of developments involved inclusion of optical systems to the rigid endoscope. In 1896 Theodor Rosenheim produced a gastroscope with three concentric tubes: the innermost contained an optical system, the middle carried the light source consisting of a platinum wire loop lamp and water cooling system, and the outermost with a scale to demarcate the distance inserted [6]. Hans Elsner built on Rosenheim’s design by adding a rubber tip to the end of the straight tube, which facilitated introduction of the instrument. However, its use was hampered by difficulty viewing through the lens once it was soiled. In 1922 Rudolf Schindler created his rigid gastroscope, a later version of which contained an air outlet to clear the lens.

Beginning in the 1930s came a period that saw the development of semiflexible endoscopes. Schindler was an integral character during this era. The first recorded flexible esophagoscope, however, was by Kelling in 1898 [7]. The lower third of his instrument could be flexed up to a 45° angle. Schindler’s breakthrough came about in 1932 in the form of the semiflexible gastroscope (Fig. 1.3). The distal half of this endoscope was constructed from a spiral of bronze with a protective covering of rubber [6]. Key to his design, though, was the discovery that using a tube filled with very thick lenses with short focal distances allowed for bending in several planes without distortion of the transmitted image. Schindler introduced an updated version 4 years later that used an electric globe as the light source [7]. The maximal bending angel was only 30°, as greater angles would not allow for image transmission, and thus there were significant blind spots not visualized by the endoscope.

A bevy of productivity by American manufacturers was responsible for a number of advancements over the next decade. William J. Cameron’s “omni-angle” flexible gastroscope included a mirror within the scope’s tip that could be flipped, allowing the viewer to scan the stomach without moving the endoscope [7]. Donald T. Chamberlin helped create an instrument with a controllable tip. This ushered in an era of endoscopes that could more thoroughly examine the stomach by minimizing blind spots that had been problematic in previous models, such as Schindler’s.

The next revolution in endoscopic development came with the discovery of fiber-optic technology . This yielded a portfolio of instruments with improved flexibility, improved light transmission, and greater field of view [6]. Basil Hirschowitz was responsible for the first “fiberscope” in 1957 (Fig. 1.4). Soon several improvements were made using Hirschowitz’s model as a foundation. Philip A. LoPresti introduced a channel for suction and air or water to keep the lens clean. Longer versions of the endoscope were created in order to reliably visualize the duodenum. Eventually four-way control of the instrument tip and deflection angles up to 180 ° were possible, further improving the field of vision. In introducing further functionality to the endoscope, the “masterscope” was designed such that a smaller fiberscope could be inserted for use in diagnostic or surgical procedures.

Inspection of the lower gastrointestinal tract dates back to simple anal and rectal specula found in the ruins of Pompei [6]. The majority of advances beyond that, however, did not come until after the advances in fiber-optic upper endoscopy instruments. The first rigid sigmoidoscope by Howard A. Kelly in 1894 used a simple lamp to reflect light off a head mirror down a tube. James P. Tuttle later integrated an electric lighting system. In general, these rigid instruments were effective in examining the first 20 to 25 centimeters of the lower gastrointestinal tract.

Beginning in the 1960s, fiber-optic technology found its way into sigmoidoscopes and colonoscopes as well. Many of the early prototypes were developed and marketed in Japan. In the United States, Robert Turell was one of the first to create a fiber-optic illumination system for use in rigid sigmoidoscopes [6]. Bergein Overholt introduced a flexible fiber-optic sigmoidoscope with the goal of improving patient comfort during the procedure. As such, his instrument allowed for deeper entry and therefore examination of a greater length of the sigmoid and descending colon. Olympus would soon after introduce a colonoscope that included a four-way controllable tip.

Oshiba and Watanabe published the first results with colonoscopy in 1965 [4]. Luciano Provenzale and Antonio Revignas are credited with performing the first complete colonoscopy in Sardinia, Italy in 1965 [6]. Their unique approach involved having a patient swallow the end of a piece of polyvinyl tubing. This eventually exited the anus, to which they then attached a Hirschowitz gastroscope and pulled it through the colon all the way to the cecum. Reports by numerous endoscopists detailing their experiences with colonoscopy and the safety of the procedure were then published. In 1977, Bohlman and colleagues published a trial demonstrating the superior diagnostic yield of flexible endoscopes compared to their rigid counterparts.

Advances in imaging enhanced the practical applications afforded by the endoscope. Taking photos of hollow organs being examined dates back to the nineteenth century with Nitze creating a cystoscope onto which glass plates with a light-sensitive coating could be mounted [7]. The plates could be moved into the light, and photographs could be created with a 3–5 s exposure time. Lange and Meltzung made attempts with a small internal camera attached to a rubber tube that the patient could swallow [6, 7]. The electric wiring for the globe, mechanical cameral trigger, and air channel for insufflation were all contained within the rubber tubing. Henning and Keilhack in 1938 used a Schindler gastroscope and overburned the globe to create a flash, producing the first color photos of the stomach [4].

Successful endoscopic photography was not achieved until the development of external photographing apparatuses. In 1948, Harry Segal and James Watson created an external device for taking color photographs through a semiflexible gastroscope. The key to this was the development of a system in which changes in light supply, gastroscope prism, and camera shutter could occur in synchrony [6].

The gastrocamera was developed in Japan in the early 1950s and introduced in the United States later that decade [6]. This instrument contained all components of a proper camera attached to a control unit: a lens, flash, air valve, and film capsule. The major disadvantages of the gastrocamera were the inability to directly view what was being photographed and the time required to develop the film. The former was remedied by Olympus in 1963 when they introduced an instrument with features of both fiber-optic technology and a gastrocamera packaged within one [6]. H. H. Hopkins contributed to the emergence of endoscopic documentation by replacing interspersed air in previous optical relay systems with glass rods [4]. His system provided superior light transmission, a wider viewing angle, and improved image quality with higher resolution. Furthermore, his system could be housed within a smaller diameter endoscope. With the improved light transmission, practitioners found that attaching a 35-mm camera to the eyepiece could yield high-quality images, and the gastroscope fell out of favor [6].