Читать книгу Successful Training in Gastrointestinal Endoscopy - Группа авторов - Страница 131

Once the cecum is reached, the most important portion of the exam begins, that is, careful inspection of the colon for pathology. In many instances, pathology such as polyps will be seen during the insertion phase and if desired can be treated at that time. Many endoscopists may also simply note the location of the lesion during insertion and take care of it during the withdrawal phase.

The first key to adequate visibility is adequate insufflation. Instilling air into the colon requires a balance between ensuring the colonic folds are adequately distended yet without creating too much tension on the colon wall and discomfort for the patient. Trainees often make the mistakes of using too little air or conversely leaving their finger on the air valve all of the time. Care must be taken and the endoscopist must always be cognizant of the degree of insufflation of the colon and patient comfort levels.

The second important factor of proper withdrawal technique is to ensure the colonic mucosa and the camera lens are clean enough to allow optimal visualization. The colon preparation often does not completely clear the colon of fecal debris. Suction can be used alone or in combination with water lavage. Some scopes are capable of having automatic water lavage controlled by a foot pedal while older scopes may still require manual injection of water. With the latter, water can be instilled to lavage the colon using a large (60 cc) syringe injected through the biopsy port just below the scope handle. As one injects, the scope is aimed with the dials and torque at the area in need of cleansing. After cleansing, suctioning is then used by positioning the scope so that the suction port is below the surface of the puddle but the camera lens is not. The location of this port varies modestly based on the model and type of scope used but as a general rule, it is best to position the target puddle at the six o'clock position. The suction button is then used and the scope repositioned as needed until the liquid is removed. This process often needs to be repeated multiple times throughout the colon to achieve adequate visualization. Trainees will frequently put the scope tip too deep into a puddle and obscure their view or repeatedly suctioning too close to the colon wall resulting in the mucosa being pulled into the suction port. If this occurs, the suction holding the mucosa in the port can be broken by either pulling the scope tip away from the mucosa or by briefly breaking the seal of the rubber biopsy port cap at the scope's handle base, thereby relieving the vacuum in the biopsy channel of the scope.

The next important skill is the development of a slow, careful inspection pattern. Inspection is carried out by developing a circular inspection pattern as the scope is slowly pulled back. This circular pattern does not necessarily need to be done with the scope tip but more with the eyes and only augmented by minor deflections of the scope tip as needed to see the entire circumference of the lumen. Scope readjustments are an ongoing process involving not only the use of the dial controls but also torque of the scope to keep the tip in the center of the lumen. As the scope passes larger folds, it is often necessary to readvance the scope just above the fold and use greater deflection of the scope tip with the dials to view behind the fold and ensure pathology is not missed. In experienced endoscopists, it is felt that a minimum of 6–7 minutes is needed to examine the entire colon adequately [9, 10]. For trainees, this process initially takes much longer due to their developing skills of scope control, inspection behind folds, and pathology recognition. As skills advance, this inspection time will gradually decline. Trainees must clearly understand that while average withdrawal time is a surrogate marker for a careful exam, the key objective is complete mucosal inspection; areas poorly seen due to the colonoscope “jumping” past folds or due to puddles must be reexamined, even if it means reinserting the scope as needed to reinspect.

The final maneuver of a colonoscopy is retroflexion within the rectum. This is performed to better inspect the distal rectum for very low‐lying polyps, internal hemorrhoids, or other perianal pathology. This is best accomplished by returning the patient to their left side if they have been repositioned during the exam. The scope is then inserted to the first (or most distal) semilunar valve in the rectum at roughly 10–12 cm from the anal verge. The large dial is then deflected maximally upward while at the same time the shaft of the scope is torqued in either direction roughly 180° and the scope inserted another few centimeters. When these three steps are done simultaneously, it should result in a view of the distal rectum with the scope shaft entering the rectal vault (Figure 6.17). The scope is then torqued in either direction to obtain views of the entire circumference of the distal rectum. On some occasions, maximal deflection of the large dial is not enough and the addition of small dial deflection in one direction or the other is needed in order to successfully retroflex the scope. This maneuver should be done with care as it is often uncomfortable for the patient and can result in perforation of the rectum if too much force or torque is used against resistance. If difficulty is encountered, maximally bending the knees toward the chest can also aid in retroflexion, though this is usually not necessary.

Figure 6.17 Retroflex views in rectum. Retroflexion in the rectum allows for better visualization of the distal rectum where polyps or other pathology such as internal hemorrhoids can often be found.