Читать книгу Successful Training in Gastrointestinal Endoscopy - Группа авторов - Страница 118

One decision that needs to be made prior to initiating endoscopy is what instrument to use. There are a number of different types of endoscopes in the gastroenterologist's armamentarium that can be selected to perform lower endoscopy. These include the standard adult colonoscope, pediatric colonoscope, flexible sigmoidoscope, or even a gastroscope that is dedicated to lower procedures (Figure 6.7). Understanding the advantages/disadvantages of each is an important cognitive skill that can improve one's chances of successfully achieving the goals of a lower endoscopy.

In general, the standard adult scope is slightly larger in diameter than the other scopes (measuring roughly 13 mm in diameter) and is one of the most commonly used scopes for colonoscopy. Its thickness results in it being somewhat stiffer than the others. As a result of being slightly stiffer, it tends to loop less than other scopes, especially in patients with a very mobile sigmoid or redundant transverse colon. By the same token, its larger diameter and decreased flexibility can also make it more difficult to navigate through fixed, sharply angulated colons. Such fixation and angulation can be seen in patients with prior abdominal or pelvic surgeries (hysterectomy, C‐sections, etc.), prior radiation, or significant prior peritoneal infection (ruptured appendix or other infection). In these patients, a pediatric scope can sometimes succeed in navigating through a difficult fixed sigmoid where an adult scope could not. This is primarily due to the greater flexibility of this scope resulting from its smaller diameter (11.5 mm diameter). In a long redundant, highly mobile colon, however, this flexibility can result in excessive proximal looping, requiring greater experience and skill to advance the scope to the cecum.

Figure 6.7 Endoscope options. Four different endoscopes can be used for lower endoscopy. Depicted here are: (A) adult colonoscope (13.2 mm diameter), (B) pediatric colonoscope (11.5 mm diameter), (C) sigmoidoscope (12.8 mm diameter), and (D) gastroscope (9.2 mm diameter). The diameter of the endoscope may vary slightly based on the manufacturer.

Gastroscopes are also used in special circumstances for lower endoscopy. Because of their smaller caliber (9.2–9.8 mm diameter), gastroscopes are ideal for lower endoscopy of an ileostomy or in a patient with an ileoanal pouch. The smaller diameter is also useful in patients who have left‐sided colonic strictures (within reach of the shorter gastroscope) that prevent the passage of either of the larger colonoscopes. For routine colonoscopy, however, these scopes loop quite a bit due to their flexibility and their short length prevents them from reaching the cecum in most cases.

Flexible sigmoidoscopes are useful if only the left colon is to be examined. Traditionally, this was the primary method for routine colon cancer screening when paired with testing such as a barium enema or fecal occult blood testing to screen the remaining colon for malignancies. For this purpose, however, colonoscopy has largely replaced flexible sigmoidoscopy (FS). FS is still useful in evaluating the severity of a flare of known ulcerative colitis, suspected ischemic or infectious colitis, to obtain colon biopsies in suspected microscopic colitis, or to evaluate radiographic abnormalities seen in the left colon.

Learning when to use each scope is a skill that comes with guidance and experience and can vary from one individual to another. Just as a golfer learns which club he/she can use most effectively in given circumstances, the endoscopist too must develop an understanding of which scope they can best employ from one case to the next. When a particular type of scope is preferred for a procedure, trainees should get in the habit of including that request at the time of booking, to better ensure that it will be available in the endoscopy unit when it is time to perform the case.