Successful Training in Gastrointestinal Endoscopy. Группа авторов

turn or the accumulation of multiple turns distal to this. In cases like this, attempts at scope advancement often simply results in recurrent loop formation. When this occurs, there are multiple techniques that can be employed. The first is simply to use suction to deflate the colon in order to reach the next turn in the colon. Often once around this next turn, better reduction of the scope can be achieved. Another is the use of abdominal pressure. Experienced endoscopy assistants can palpate the abdomen and feel the location of scope looping. External abdominal pressure can then be applied over that area in an attempt to keep the scope from looping again. This simply translates the force of scope advancement further along the shaft rather than being used up in loop development. If there is a question as to where the best sight for external pressure might be, viewing the video display while palpating various spots in the abdomen might give a clue. While palpating, a site that results in slight scope tip advancement may be an ideal location for application of external pressure [19]. Conversely, a site that results in slight scope retreat might hinder scope advancement and increase the likelihood of loop formation. Another method used to prevent recurrent looping is to reposition the patient to a supine position (and in rare instances to a prone position) [20]. This tends to be of benefit by changing the orientation of how the colon is laying in the abdominal cavity and often can result in an orientation more favorable to reaching the cecum. This repositioning is most effective while navigating through the right colon but can also be used to relax acute angulations encountered elsewhere in the colon.

Figure 6.28 Torque to open folds. When less acute turns are encountered, the folds can often be pushed aside by advancing the scope tip just past the fold and torquing the scope shaft into them (a). This allows a straight shaft to allow easy advancement (b). This technique is often used repeatedly in opposite directions, especially through the sigmoid colon (c).

      (Copyrighted and used with permission of Mayo Foundation for Medical Education and Research.)

      Ileocecal valve

Intubation of the ileocecal valve is really no different than navigating an angulated turn as described above. The location of the valve is readily identifiable by the asymmetric thickened fold just above the cecum. The valve lies within the thickened fold. In difficult‐to‐identify valves, the appendiceal orifice can serve as a clue to its location. Following the concave portion of the appendiceal orifice as if it were a bow shooting an arrow, the valve should be located in the direction this “bow” would shoot the arrow.

Occasionally, the os can be seen without special maneuvering and entered directly. More often, however, navigating through the valve requires the use of the torque or dial technique to open up the folds just as described in the section “Angulated turns.” One should advance the scope just past the valve so it is just off the screen. Slight torque or dial deflection is used in the direction of the valve as the scope is very slowly withdrawn. The key to this is to only use “slight” torque or dial deflection as too great of deflection will simply hook the tip of the scope behind the valve. The tip should just lightly brush across the folds of the valve as the shaft is pulled back (Figure 6.29) (Video 6.10). Once the first fold (cecal side) is seen, the withdrawal is stopped and gradually increasing torque or deflection is used to steer the scope tip between the two folds making up the valve. Puffs of air, by tapping on the air valve, can keep the mucosa off of the lens, allowing better identification of the os. Once the os is identified, the scope shaft can be advanced, pushing the scope tip into the terminal ileum.

A common mistake of trainees is simply coming alongside the valve and trying to use all dials in hopes that the scope tip will fall into the terminal ileum. Occasionally, this does work, but as described in the previous section, this results in a very angulated scope tip and loss of the force vector (Figure 6.30). Pushing the scope in this scope configuration will simply advance the scope shaft into the base of the cecum, which often leads to paradoxical regression of the scope tip, causing it to fall out of the valve. In instances where the ileocecal valve is inverted toward the base of the cecum, advanced endoscopists will utilize a maneuver of retroflexing the scope tip in the cecum to view the valve en face. In this scope configuration, the inverted valve can then be intubated by slowing pulling back on the scope. This maneuver can create significant pressure along the cecal wall however, thus should be used cautiously and only by experienced endoscopists when cecal intubation is necessary.

Figure 6.29 Terminal ileum intubation. To intubate the ileocecal valve, the scope tip should be brought alongside the valve and gentle deflection of the tip toward the valve used as the scope is slowly drawn back. Too much deflection will often result with the scope tip simply hooking behind the valve in the cecum. Once past the first fold of the valve, the endoscopist stops withdrawing and uses a combination of torque and slightly more tip deflection to open the valve. This leaves the scope in better position to be advanced once the os is intubated.

      (Copyrighted and used with permission of Mayo Foundation for Medical Education and Research.)

Figure 6.30 Incorrect TI maneuver. Like the acute turns, novice endoscopists will often rely on excessive dial controls to attempt to intubate the ileocecal valve. This makes the scope difficult to advance, typically resulting in the scope loop advancing into the cecum and the tip falling out of the valve.

      (Copyrighted and used with permission of Mayo Foundation for Medical Education and Research.)

How to teach and assess colonoscopy skills

      Identifying methods best suited to teach colonoscopy can be quite difficult. Traditionally, these skills have been taught at the bedside during patient‐based endoscopy. However, with computer simulation models, as well as live and ex vivo animal models, evidence would suggest that these alternatives to patient‐based endoscopy can impart some of these motor and cognitive skills [21, 22]. In the case of early motor skills, this can also be done more safely, economically, and with better patient outcomes [23].

A second problem with the current state of colonoscopy education is that skills are primarily taught all together from the first day without differentiation between beginning or intermediate skills. In traditional training, a trainee is commonly forced to attempt to learn intermediate skills such as loop reduction and navigation of fixed angulated turns at the same time he/she is learning simply how to use the dials and steer the scope. This produces a great deal of stress for the trainee not to mention some element of discomfort or even increased risk for the patient. Breaking the procedure down into individual skills, greater utilization of alternate teaching tools such as texts, multimedia, and simulation, training can proceed in a more stepwise fashion, starting with focused instruction of the most basic skills first and then on to more advanced skills when ready. Education literature has well established that building skills in a stepwise fashion is the most effective learning model [24]. This is not to suggest that these teaching aids will replace patient‐based training, but rather these training tools can be used to effectively augment patient‐based training and improve on the traditional training model. In this final section, we will examine the methods by which each of these skill groups previously outlined can best be taught.

The final focus of this