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There are three techniques used to handle the scope. The “one‐handed” technique is the one most commonly used by experienced colonoscopists as it provides the most uninterrupted control of the scope shaft and is best suited to the predominant use of torque to maneuver the instrument (Figure 6.14). In this method, the dials are controlled with the left hand alone, relying primarily on the up/down dial. The right hand remains on the shaft of the scope providing torque, advancement, and withdrawal of the scope. A useful way to conceptualize this technique is to imagine flying a plane through a tunnel. If the pilot wishes to turn right, one cannot simply fishtail the plane to the right, instead the plane must roll right and then pull back on the stick (up). Occasionally, the right hand may still need to be brought up to control the smaller right/left dial but only with particularly tight turns, such as the splenic or hepatic flexure, where torque and up/down deflection may not be sufficient.

Figure 6.13 Torque to change from horizontal to vertical. The two images depict the same turn but in different orientations. In the first image (a), the turn goes off to the right and would require the use of the small left/right dial to navigate. However, after torque of the scope shaft 90° clockwise, this turn is now oriented vertically (b) and can now be navigated with the large dial alone.

Figure 6.14 One‐handed technique. With the one‐handed advancement technique, all of the dial control is done by the left hand, primarily using the large dial. The right hand is responsible for providing torque and advancement, and generally does not leave the scope shaft.

The “two‐handed” technique is favored by some experts who feel that when the thumb is used to cross over to the small dial, fine control of the large dial is not possible. Additionally, the left thumb cannot maximally deflect the small dial in either direction. Once the right hand has turned the small dial, it can be temporarily locked in this position to hold the intended deflection while the right hand returns to the scope shaft (Figure 6.15). The major drawback to this technique is the intermittent interruption of control of the scope shaft with the right hand. When the hand is off the shaft, the scope frequently can fall back unintentionally or rotate due to loops. Many endoscopists who employ the two‐handed technique can compensate for this decreased shaft control by positioning the scope shaft so that it hangs down by the side of the table, pinning the scope shaft between the endoscopist's thigh and the side of the bed and rapidly moving the right hand back and forth between shaft and the outer small dial. Another stabilization method is to reach down with the left hand and while holding the scope, loop the left fifth digit around the scope shaft roughly 20 cm away from the anus and pinning it against the left palm while the right hand is busy maneuvering the right/left dial [8]. This is particularly useful when a free right hand is needed to advance a therapeutic tool down the scope shaft or if the right left knob is needed to fine‐tune targeting a tool as it will hold any necessary torque in the scope shaft and allow small forward and backward adjustments in scope advancements with the left hand.

Figure 6.15 Two‐handed technique. With the two‐handed technique, the right hand is moved back and forth between the shaft of the scope and the small right/left dial, while the left thumb controls the large inner dial.

A third method is called the “two‐person” technique and is rarely used anymore. It involves the endoscopist using the two hands to control the dials exclusively while an assistant advances the shaft of the scope at their order. Again, this technique is typically no longer taught due to the many disadvantages of coordinating scope control, much like having one person steer a car while another operates the gas and brakes.