Successful Training in Gastrointestinal Endoscopy. Группа авторов

Figure 6.8) and extending on the outside of the forearm. The base of the scope handle is held between the palm and the fourth and fifth digit. The left elbow is bent in a comfortable position to allow the arm to carry the weight of the scope for long periods of time. The right hand holds the shaft of the scope and is kept within 20–30 cm from the anal opening to allow maximum control of the shaft. The shoulders would be in a comfortable position and the height of the bed should be at a level that allows the endoscopist to stand with the hips and back straight to avoid overuse of the back muscles. In this position, the right elbow should also be bent at roughly 90°. Trainees need to be instructed early on how to correctly set the height of the bed, proper posture, and position of the arms. Improper posture or form can lead to muscle fatigue and chronic musculoskeletal problems over an endoscopist's career [7].

      Scope dials

On the medial side of the scope, there are two dials with sprockets (Figure 6.9). These dials control the deflection of the flexible scope tip and are used to steer the scope during advancement and to direct the video camera's field of view during mucosal inspection on the withdrawal phase of the exam. The large inner dial deflects the scope tip up (counterclockwise dial rotation) and down (clockwise). The smaller, outer dial controls left (clockwise) and right (counterclockwise) tip deflection. Since the orientation of the camera in the scope's tip is fixed in relation to the control mechanisms, the direction of tip deflection is always in relation to the video image on the display monitor, regardless of how the scope is torqued. Ideally, both dials are controlled with the left thumb, but as you will see later, the smaller dial is used less frequently as most steering directions can be achieved with rotation of the scope and the up/down control alone (referred to as torque steering).

Figure 6.8 How to hold the scope. These images demonstrate the proper manner in which to hold a colonoscope. (a) The scope is held in the left hand with the cable exiting posteriorly between the thumb and index finger. (b) The handle is held with the fourth and fifth digits freeing the thumb and remaining fingers to operate the controls.

Figure 6.9 Scope dials. The colonoscope's dials are shown here. The large inner dial deflects the scope tip up or down as indicated by the arrows. Similarly, the small outer dial deflects the scope tip left or right.

      Next to these dials there are two levers that can be used to lock their respective dial in place in order to hold the scope tip in a deflected position and free up the endoscopist's hands during therapeutic maneuvers. In general, however, it is important to remember that during the scope advancement or withdrawal, these dials should be “unlocked” in order to reduce the risk of colonic perforation due to a rigid scope tip.

Figure 6.10 Scope valves. The top “red” valve activates the scope's suction when pressed. The “blue” valve controls air insufflation when lightly touched as well as water to rinse off the lens when fully pressed.

      Scope valves

In the front of the scope handle, there are two valves (Figure 6.10). The upper “red” color‐coded valve provides suction through the working channel of the scope. When pressed all the way in, the suction can be used to remove air from the colon and improve mucosal visualization by suctioning up retained liquid within the colon, or when a trap is employed in the suctioning circuit, it can be used to retrieve removed polyps (Figure 6.11). This valve is typically controlled with the left index finger.

The lower “blue” valve has dual functions of air insufflation and water rinse of the camera lens. This valve can be controlled with either the index finger or middle finger. When the fingertip is lightly placed occluding the hole in the middle of the valve, air is forced down the scope, resulting in inflation of the colon lumen. One common error many trainees make is to “rest” their finger over this opening, resulting in overinflation. Care must be taken to limit the amount of air used during endoscopy as excessive distention of the colon results in greater patient discomfort as well as increasing the risk of colonic perforation (particularly in the thin‐walled cecum). The second function of the valve (water rinse of the camera lens) is achieved by pressing in the blue valve completely. This results in a fine jet of high‐pressured water to be sprayed horizontally across the tip of the scope, rinsing away adherent debris that can reduce or obscure the camera's visualization of the colon. Some colonoscopes also include a special port for irrigation of the colon controlled by a foot pedal. This can be used to clean the colonic mucosal to improve inspection when suboptimal preparations are encountered. An alternative to this is simply injecting water through the biopsy port of the scope using a large syringe. If using the syringe method, a small amount of simethicone can be added to this water to assist when bubbly or foamy fluid is encountered in the colon.

Figure 6.11 Trap in suction circuit. When a polyp is removed with a snare, a trap is needed to collect the tissue. This trap is placed in the circuit of the scope's suction line. This trap allows liquid and air to be suctioned normally but traps larger particles such as polyp tissue in a small chamber. This allows the removed polyp to be collected by suctioning it up through the working channel of the scope by pressing the red valve.

      Scope insertion

Prior to insertion of the scope, a digital rectal exam is performed for the dual purpose of lubricating the anal canal as well as examining the canal for pathology and patency. The right hand is ideally double gloved so that following the rectal exam, the outer glove can be removed and discarded without the need for regloving. The scope handle is draped over the endoscopist's left shoulder or laid on the bed freeing the left hand to lift the upper gluteal fold exposing the anal canal. The anal area is visually inspected for pathology and then the rectal exam performed with the right index finger. Following the exam, the outer glove is discarded. The distal 20 cm of the scope is then liberally lubricated. The scope insertion into the rectum is then performed by one of the following manners (Figure 6.12) (Video 6.2):

Figure 6.12 Rectal intubation techniques. This illustration demonstrates the three common methods of inserting the scope through the anal canal: (a) tangential approach, (b) along‐side finger, and (c) straight insertion.

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

      1 Tangential