ESD Expansion: NOTES—The Western Perspective

Fig. 23.1

Insulated tip knife, hook knife, flush knife, triangular tip knife, sphincterotome

Peritoneal Inspection

Control of pneumoperitoneum is a particular challenge in NOTES. Controlled insufflation through the endoscope is difficult and can result in wide variations of intraperitoneal pressures and potential for overinflation. Spatial orientation is also an issue, particularly for endoscopists who are not traditionally accustomed to intentionally visualizing the peritoneal cavity. This is likely overcome by familiarity with the procedure and development of controlled insufflation devices that can be used with the endoscope. During intraluminal endoscopy, a wide endoscopic viewing field and use of a distal cap have been utilized for improved visualization. Similar developments may aid inspection during NOTES.

Retraction

Retraction of abdominal organs in the peritoneal cavity is a challenging problem in NOTES. The flexibility of the endoscope complicates retraction. During intraluminal endoscopy the walls of the GI tract provide traction for the scope, which allows stabilization as well as deployment of endoscopic instruments through the scope. The instruments used during endoscopy are also too flexible to be utilized for retraction. The challenges of retraction were initially answered by using rigid equipment; this is an option in transvaginal, transcolonic, and transvesical NOTES. Additionally, utilization of a single transabdominal port has been attempted in what has been termed “hybrid NOTES.”

Dissection

Endoscopic dissection is the most time-consuming aspect of ESD. The knives developed for ESD have been specifically designed for ease of dissection. Many of these knives have features that make dissection in the submucosal plane safe, by enabling injection of liquids into the submucosa (water jet function) or preventing full-thickness cautery injury (insulated tip knife). Many of these knives have been used in NOTES, however similar dissecting challenges exist. In ESD, dissection along the submucosal plane is a challenge, as well as identification of submucosal vessels. With increased user experience, the risk of bleeding during ESD has been shown to decrease. Challenges in identifying vessels, nerves, lymphatics, and other structures are similar during NOTES.

Closure

Closure of the access site is the most studied aspect of NOTES; likely, current endoscopic practice could translate well. There are multiple closure devices on the market, for many different applications, that could work well for intentional closure of the viscera during NOTES, including conventional endoscopic clips, T-tags, T-bars, suturing devices, staplers, and over-the-scope clips (OTSC). These methods could likely all be used equally well, despite the point of access including the esophagus, stomach, colon, or non-digestive organs such as the vagina and bladder. Additionally, standard surgical closure techniques could be considered.

Post-procedure Considerations

There is concern by those investigating NOTES regarding sterilization of instruments and whether there is potential for infectious spillage of gastrointestinal flora through the access ports. Several methods have been proposed for sterilization of endoscopes to prepare them for NOTES. The quickest and cheapest method involves a 0.2 % peracetic acid solution. The longest and most expensive, though most stable, method involves ethylene oxide gas sterilization [7]. Precautions to decontaminate the GI tract have also been attempted, including 24-h preparations using a liquid formula diet, antibiotic irrigation, and systemic antibiotics [8]. Despite theoretical reduction in contamination from the access site by sterilization of the endoscopic tools or reducing flora, other reports have suggested that transgastric access may not result in postoperative infection any more than other procedures/surgeries [9].

Other factors that affect the effectiveness of the operator during NOTES include adequate air insufflation into the abdominal cavity and retraction of adjacent structures and organs. Not only do the instruments developed for NOTES procedures alter visualization, but familiarity with the procedures and adequate training are paramount.

Clinical Applications of Notes

Appendectomy and Cholecystectomy

The human experience with NOTES is somewhat limited; however, it continues to show promise. In 2003, the first NOTES procedure, a transgastric appendectomy, was performed on a human [10]. Multiple other procedures have been performed since that initial appendectomy. The first transluminal cholecystectomy was performed in France using a similar procedure, followed shortly thereafter in Italy and Brazil [11]. Transgastric rescue of a dislodged gastrostomy tube through the previous gastrostomy site was initially described in 2007 and continues to be used by those who initially described the procedure as an alternative to surgical rescue of prematurely dislodged gastrostomy tube [12]. Over 4,000 transvaginal NOTES have been reported, making the transvaginal approach the most commonly used for NOTES to date. Few complications have been reported and selected centers are commonly using a transvaginal approach as the standard procedure for cholecystectomy [13]. Limitations obviously include exclusive use in females and public concern regarding injury to adjacent structures.

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