Successful Training in Gastrointestinal Endoscopy. Группа авторов

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.

Intermediate skills

      In this section, the focus will be on those cognitive and motor skills required to be proficient at routine colonoscopy. Specifically, this section will address the cognitive skills of pathology recognition, the selection and settings of basic therapeutic devices, and the management of complications. The motor skills addressed here will include the basic management of loops, difficult turns, TI intubation, and the use of the basic biopsy cable and snare. More advanced skills such as those needed in complex or therapeutic endoscopy will be covered in later chapters.

      Intermediate cognitive skills

      Pathology recognition

Colonoscopy is not simply reaching the cecum and performing a careful inspection during withdrawal; it also involves the ability to identify and manage potential pathologic findings such as polyps or inflammation. Skilled detection of abnormalities requires a careful inspection process and rapid recognition of variances in the mucosa. The method of inspection was discussed earlier in this chapter. Here, the stress will be on the development of recognition of abnormalities. This skill of rapid pathology identification by experienced endoscopists is a result of the cognitive skill of pattern recognition. Pattern recognition is the ability to quickly identify small changes and understand their meaning, much like a master chess player can look at a complex arrangement of chess pieces on a board and quickly understanding the implications, such as which player will eventually win the game and how it can be done. This pattern recognition is the key factor that allows an experienced endoscopist to quickly scan the mucosa and continue the withdrawal with greater speed than trainees. This skill typically is acquired only with experiencing firsthand the broad spectrum of normal and abnormal findings with considerable repetition but can be augmented with the self‐study of photo atlases or online resources (especially for rare endoscopic findings) (Figure 6.18) (Video 6.4). Over time and with careful supervision and guidance by instructors, this skill is eventually acquired to a sufficient level to operate independently (competence), but skills will continue to be honed throughout the lifetime of the endoscopist. Education researchers have suggested that it takes roughly 10,000 hours of experience to become a “master” at whatever it is one wishes to do, be it playing chess, sports, or performing endoscopy [11]. Basic competence, however, occurs much earlier, yet what defines basic competence in this skill is difficult to assess. Later in this chapter, we will discuss how best to teach these skills of pathology recognition as well as how best to assess these skills as the trainee works toward competence.

      Device selection and settings

      As fellows begin to identify pathology such as polyps, the next cognitive skill that must be acquired is how to best manage the abnormality. Part of this management is the hands‐on motor skills of applying therapy and will be covered later in this chapter. The cognitive components of this skill include selection of the ideal device, such as a biopsy forceps or cold/electrocautery snare. Additionally, if electrocautery is used, one must also understand what settings to use on the current generator to ensure ablation of the pathologic findings yet minimize risks of post‐treatment ulcerations, bleeding, or perforation. As with all skills that require coordination with an assistant, trainees must become facile with communication of directions. This section will focus on these basic issues as they pertain to simple polyp removal.

      The goal of polyp removal is for both diagnostic purposes (histology) as well as therapeutic to ensure no residual adenomatous tissue remains. Very small polyps (<3 mm) can typically be removed effectively with simple cold biopsy (i.e., no electrocautery). This is performed by grasping the polyp with a biopsy forceps. The open forceps is placed over the polyp and closed to grasp the entire polyp. With a quick tugging maneuver, the polyp is plucked off the mucosal surface and the cable withdrawn. The tissue is saved for diagnostic microscopic examination. This process results in only a small amount of oozing at the biopsy site and rarely results in any immediate or delayed complications.

Slightly larger polyps pose a different problem. Simple cold biopsy tends not to completely remove the polyp. Some endoscopists may take multiple cold biopsies until the polyp appears removed. This approach is safe but runs the risk of leaving some small amount of adenoma behind and is generally discouraged. Hot biopsy is also a technique that has fallen out of favor due to increased risks for post polypectomy ulceration and bleeding. Instead, the use of cold snare is the generally accepted method for en bloc polypectomy for lesions ranging up to 10 mm in size [12]. This technique is performed by placing an open snare around the polyp with the snare's catheter near the base of the polyp (Figure 6.19). The snare is then slowly closed by an endoscopy assistant until the wire loop is snuggly around the base of the polyp. Care must be taken to ensure as little normal surrounding tissue is caught within the loop of the snare but also that the entire polyp is included. The assistant is then instructed to apply greater force to cause the wire loop to close further and cut through the tissue at the base of the polyp. The snare is then removed and the polyp tissue is then suctioned up through the scope and collected in a trap placed in the suction circuit. Cold snare polyp removal is quite effective for these slightly larger (3–9 mm) polyps and does not result in much immediate bleeding despite their increased size. Cautery is typically not needed for polyps in this size but can be employed if needed. For lesions ranging from 10 to 20 mm in size, en bloc resection is typically performed with an electrocautery snare.

An electrocautery snare is a monopolar device. Monopolar devices require placement of a grounding pad on the patient (typically on the hip or thigh), which is also connected back to the ground outlet on the power source to complete the circuit. The polyp is then grasped by the snare in an identical process as the cold snare technique. The polyp is lifted tenting up its attachment to the colon wall. Care is taken to ensure the cable or gasped tissue is not touching any other part of the colon, such as the wall opposite the polyp. This is to ensure collateral cautery injury does not occur. The endoscopist then pushes a foot pedal that activates the generator sending a current of electricity down the cable, through the polyp and patient to the grounding pad and back to the generator's ground. This current results in heat due to the conductive resistance of the tissue, resulting in destruction of tissue at the polyp site and allowing the snare to cut through the polyp base while cauterizing any vessels as it cuts. Typically, a coagulation current (with a blend of cutting current) is used with a power setting of 15–20 watts [13]. Some would argue lower settings can reduce the risk for post‐polypectomy ablation complications [14]. Others propose using predominantly a cutting current to further reduce the risk for thermal injury to the site, but this also may increase the risk for immediate bleeding complications. The heating effect created by the current is most intense at the cable/tissue interface and as the current runs deeper through the tissue, this effect dissipates based on the distance from the cable/tissue interface. Although this results in good ablation of polypoid tissue, this also results in