Natural orifice translumenal endoscopic surgery (NOTES) is an intense area of research, and is arguably the most significant endoscopic innovation of this decade. Training for new NOTES is a relatively long, encompassing advanced endoscopy training, mastery of endoscopic dexterity within the narrow submucosal or “third space” with an in-depth understanding of the tissue planes. Proficiency with new closure and hemostatic devices is also essential. Few institutions worldwide can provide all the cognitive and technical elements essential to train new NOTES trainees. Trainees may need to spend time across several institutions to ensure safe and effective practice of new NOTES.
Key points
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Natural orifice translumenal endoscopic surgery (NOTES) is an intense area of research, and is arguably the most significant endoscopic innovation of this decade.
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After initial enthusiasm of ideas, there was some early disappointment owing to the limitations of instruments and accessories to facilitate intraabdominal surgery via flexible endoscopes.
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“New NOTES” procedures have been performed by both gastroenterologists and GI surgeons worldwide.
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This paper outlines the current status of new NOTES procedures and the skills and training required for the new generation of trainees to become proficient in new NOTES.
Introduction
The concept of natural orifice translumenal endoscopic surgery (NOTES) has been a radical and innovative idea that changed the way we think about the field of endoscopy and minimally invasive surgery. In 2004, Kalloo and colleagues performed the first transgastric peritoneoscopy in a porcine model. Next, Rao and Reddy demonstrated the first human transgastric natural orifice translumenal endoscopic surgery (NOTES) appendectomy. In 2005, the American Society of Gastrointestinal Endoscopy and Society of American Gastrointestinal Endoscopic Surgeons formed a working party of gastroenterologists and surgeons, namely the Natural Orifice Surgery Consortium for Assessment and Research, with the aim of safely developing and introducing NOTES techniques.
After initial enthusiasm of ideas, there was some early disappointment owing to the limitations of instruments and accessories to facilitate intraabdominal surgery via flexible endoscopes. Nevertheless, 10 years later, the concept of NOTES has become a clinical reality. After extensive investigation carried out in animal models and cadavers, we have seen an eruption of various NOTES procedures, including the initial human transgastric cholecystectomy, transvaginal cholecystectomy, transvaginal nephrectomy, and transanal mesorectal resection. However, such procedures have not been adopted widely in clinical practice and some would argue that NOTES is “dead” because the hype has not generated a revolution as was seen with laparoscopic surgery in the 1990s. This argument is likely misguided.
It is best to consider that NOTES is not a technique, but a concept of accessing organs or tissue beyond the lumen of the gastrointestinal (GI) tract. As the skill set of NOTES pioneers and interventional endoscopists became more sophisticated, they began pushing the limits of what could be accomplished endoluminally, eventually exiting the confines of the GI lumen. Along the way, the “third space” that lies within the wall of the gut became apparent.
There has been extensive dialogue with regard to who is best suited to carry out NOTES procedures. With regard to traditional NOTES, opinion over time has largely favored a multidisciplinary team combing the skill sets from both gastroenterologists and GI laparoscopic surgeons. However, “new NOTES” procedures have been performed by both gastroenterologists and GI surgeons worldwide. This paper outlines the current status of new NOTES procedures in addition to the skills and training required for the new generation of trainees to become proficient in new NOTES.
Introduction
The concept of natural orifice translumenal endoscopic surgery (NOTES) has been a radical and innovative idea that changed the way we think about the field of endoscopy and minimally invasive surgery. In 2004, Kalloo and colleagues performed the first transgastric peritoneoscopy in a porcine model. Next, Rao and Reddy demonstrated the first human transgastric natural orifice translumenal endoscopic surgery (NOTES) appendectomy. In 2005, the American Society of Gastrointestinal Endoscopy and Society of American Gastrointestinal Endoscopic Surgeons formed a working party of gastroenterologists and surgeons, namely the Natural Orifice Surgery Consortium for Assessment and Research, with the aim of safely developing and introducing NOTES techniques.
After initial enthusiasm of ideas, there was some early disappointment owing to the limitations of instruments and accessories to facilitate intraabdominal surgery via flexible endoscopes. Nevertheless, 10 years later, the concept of NOTES has become a clinical reality. After extensive investigation carried out in animal models and cadavers, we have seen an eruption of various NOTES procedures, including the initial human transgastric cholecystectomy, transvaginal cholecystectomy, transvaginal nephrectomy, and transanal mesorectal resection. However, such procedures have not been adopted widely in clinical practice and some would argue that NOTES is “dead” because the hype has not generated a revolution as was seen with laparoscopic surgery in the 1990s. This argument is likely misguided.
It is best to consider that NOTES is not a technique, but a concept of accessing organs or tissue beyond the lumen of the gastrointestinal (GI) tract. As the skill set of NOTES pioneers and interventional endoscopists became more sophisticated, they began pushing the limits of what could be accomplished endoluminally, eventually exiting the confines of the GI lumen. Along the way, the “third space” that lies within the wall of the gut became apparent.
There has been extensive dialogue with regard to who is best suited to carry out NOTES procedures. With regard to traditional NOTES, opinion over time has largely favored a multidisciplinary team combing the skill sets from both gastroenterologists and GI laparoscopic surgeons. However, “new NOTES” procedures have been performed by both gastroenterologists and GI surgeons worldwide. This paper outlines the current status of new NOTES procedures in addition to the skills and training required for the new generation of trainees to become proficient in new NOTES.
Long-range and short-range (new) natural orifice translumenal endoscopic surgery
It is important to recognize that not all NOTES procedures are the same. NOTES can broadly be divided into 2 categories: long-range and short-range NOTES. Long-range NOTES refers to procedures where access through a healthy visceral organ is gained to target another, distant organ (eg, transgastric appendectomy). Short-range NOTES refers to procedures whereby the organ of interest is accessed directly, without disrupting another organ (eg, peroral endoscopic myotomy [POEM]). Other examples are listed in Table 1 .
| Short-Range NOTES | Long-Range NOTES |
|---|---|
| POEM | Transgastric cholecystectomy |
| EFTR | Transgastric appendectomy |
| STER | Transvaginal cholecystectomy |
| G-POEM | Transvaginal appendectomy |
It has become clear to operators that long-range NOTES requires not only advanced endoscopic skills, but also knowledge of intraabdominal anatomy and the ability to manage complications such as bleeding. For patient safety, conversion to laparoscopic or open surgery remains a possibility and therefore surgical skills are paramount. It has been well-accepted that, for safe and successful application of long-range NOTES, a multidisciplinary team of practitioners including surgeons and gastroenterologists is required.
On the other hand, short-range or “new NOTES” procedures are largely performed in the third space. Hence, advanced endoscopic skills including submucosal dissection are the vital skill constituents for the operator.
Skill set for new natural orifice translumenal endoscopic surgery
The ongoing challenges of traditional NOTES procedures do not apply to new NOTES. For instance, transvisceral access to the peritoneal cavity for resection of intraabdominal organs (eg, cholecystectomy, appendectomy) requires triangulation of instruments and detailed knowledge of intraabdominal anatomy. Laparoscopic surgical skills are also mandatory to ensure safety of the procedure as well as potential conversion in the event of inability to complete the resection via NOTES techniques or occurrence of complications.
In contrast, the skill set pertinent to new NOTES are those of an advanced endoscopist ( Box 1 ). Advanced techniques such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) are well-investigated methods for endoscopic resection of superficial GI neoplasms. ESD operators have developed expertise in recognizing and working within the layers of the GI tract. Appreciation of the planes is essential for performing submucosal endoscopy, the most successful off-shoot of NOTES procedures. New NOTES procedures include POEM, submucosal tunneling and endoscopic resection (STER), endoscopic full-thickness resection of tumors (EFTR), and peroral endoscopic pyloromyotomy (G-POEM). These procedures offer minimally invasive therapeutic options for motility disorders (achalasia, spastic esophageal disorders, gastroparesis) and subepithelial masses of the upper GI tract (eg, GI stromal tumors, leiomyomas). Mastery of endoscopic dexterity within the narrow submucosal or “third space” with an in-depth understanding of the tissue planes is essential for technical expertise.
Essential
Endoscopy
Colonoscopy
EMR
ESD
Desirable
EUS
Abbreviations: EMR, endoscopic mucosal resection; ESD, endoscopic submucosal dissection; EUS, endoscopic ultrasound; NOTES, natural orifice translumenal endoscopic surgery.
To manage motility disorders, the operator should either have an in-depth understanding of the disorders and ability to interpret manometry studies, or have a close collaboration and working relationship with a gastroenterologist with a special expertise in motility disorders. With regard to subepithelial lesions, the appropriate resection technique depends the layer of origin of the mass. Endoscopic ultrasonography plays a very important role in not only identifying the origin of the lesion, but also proximity of associated structures, such as the great mediastinal vessels. Hence, the operator should either be proficient in performing endoscopic ultrasonography or work closely with an endosonographer who can communicate the findings of the examination relevant to endoscopic resection. The new NOTES procedures are reliant on the endoscopists’ familiarity and knowledge of submucosal dissection, therefore ESD experience is an advantage. In particular, the operator should be familiar with ESD principles, techniques, equipment, and cautery settings. Last, and most important, to achieve complete success of these procedures, the new NOTES operator should also have mastery in the management of potential endoscopic complications such as bleeding, mucosal perforation, or full-thickness perforation. Hence, use of endoscopic hemostasis devices and proficiency of closure techniques using through-the-scope (TTS) clips, over the scope clips (OTSC, Ovesco Endoscopy AG, Tübingen, Germany), endoscopic suturing (Overstitch, Apollo Endosurgery, Austin, TX, USA; Boxes 2 and 3 ).
ESD knives
Coagraspers
TTS clips
Endoscopic suturing device
OTSC
Abbreviations: ESD, endoscopic submucosal dissection; NOTES, natural orifice translumenal endoscopic surgery; OTSC, over the scope clip; TTS, through the scope.
Spare ESD knives
Fully covered and partially covered enteral stents
Veress needle
Cyanoacrylate glue
OTSC
Injector needles/catheters
Abbreviations: ESD, endoscopic submucosal dissection; NOTES, natural orifice translumenal endoscopic surgery; OTSC, over the scope clip.
Who currently performs new natural orifice translumenal endoscopic surgery?
Peroral Endoscopic Myotomy
POEM is an incisionless therapeutic procedure that shows great efficacy for the treatment of achalasia and spastic esophageal disorders. The technique was developed in 2007 by Pasricha and colleagues in a porcine model and subsequently translated to clinical practice by Inoue and associates in 2008. The 4 steps are (1) mucosal incision, (2) submucosal tunneling, (3) myotomy, and (4) closure of mucosal incision. Maintaining an intact mucosa prevents leakage of esophageal contents and is the key to the safety of the procedure. Seven years later the technique has been adopted world-wide. More than 10,000 procedures have been performed with technical and clinical success rates ranging from 71% to 100%. An international survey performed in 2012 identified 25 POEM operators. Of these, 14 were surgeons and 11 gastroenterologists. The majority (84%) of all operators had prior ESD experience. Interestingly, only 66% of operators had experience of long-range NOTES procedures and 25% of operators performed POEM in the endoscopy suite (as opposed to operating room). Very few complications related to POEM have been reported to date. Capnoperitoneum (8.3%) and inadvertent mucosal perforation or mucosotomy (6.7%) are minor technical adverse events that can be managed during the procedure. A Veress needle can be temporarily placed transabdominally to drain a capnoperitoneum. Mucosotomies can generally be managed endoscopically with clips or endoscopic suturing and seem to decrease in frequency with increase in operator’s experience. Serious adverse events (mediastinitis, abscess, leak, delayed bleeding ) are extremely rare (<0.1%) with only 2 reports of esophageal perforation requiring surgical (laparoscopic and thoracoscopic) intervention. Recently, Li and colleagues reported on a total of 3 out of 428 patients (0.7%) who had postoperative delayed bleeding within the submucosal tunnel. Patients presented with severe retrosternal chest pain or hematemesis. The clips were removed and blood clots extracted from the tunnel, after which a bleeding vessel was identified and treated using hemostatic forceps in two-thirds of patients. In the third patient, a bleeding source could not be identified and a Sengstaken-Blakemore tube was immediately placed. The gastric balloon was immediately deflated and esophageal balloon deflated at 24 hours. All cases were managed endoscopically without need for surgical intervention or blood transfusion. Decompressing the tunnel prevented mucosal ischemia and necrosis, which could lead to full-thickness perforation. Intraprocedural bleeding is commonly encountered, although there are no reports of inability to complete POEM owing to massive bleeding. Hemostatic techniques commonly used during POEM include use of coagraspers (Olympus, Center Valley, PA, USA; Fig. 1 ), water-jet–assisted knives (ERBE, Tübingen, Germany; Fig. 2 ), or mechanical tamponade using a blunt catheter or the distal cap.
Most operators perform POEM in the operating room. However, we recently published efficacy and safety outcomes on 60 consecutive patients who underwent POEM in an endoscopy unit performed by an interventional gastroenterologist. Mean procedure time was 99 minutes, and clinical success was achieved in 92.3% of patients. Only 10 adverse events occurred, and the majority were mild (n = 7) with no severe adverse events. Inadvertent mucosotomies occurred in 4 patients, all of which were controlled endoscopically (TTS clips, OTSC, and cyanoacrylate). Significant pneumoperitoneum occurred in 3 patients, which were successfully decompressed with a Veress needle (Genicon, Winter Park, FL, USA). One patient on chronic immunosuppression therapy (including steroids) experienced symptomatic intraprocedural pneumothorax, which was treated successfully with insertion of a chest tube within 10 minutes of diagnosis. There are many advantages to performing POEM in the endoscopy unit. Gastroenterologists are adept at performing procedures in the endoscopy suite, which is usually set up in an ergonomic manner for various endoscopic procedures. Importantly, all necessary endoscopy equipment and accessories are available within short reach (particular for adverse event management). Furthermore, familiarity and comfort with the surrounding environment is important for both the endoscopist and the assisting team when performing challenging procedures such as POEM.
POEM is a successful and safe new NOTES procedure that has been adopted worldwide by both gastroenterologists and surgeons who have endoscopy and ESD experience and can be safely performed either in the operating room or endoscopy suite. Long-range NOTES or surgical experience does not seem to influence the operator’s ability to safely and successfully perform POEM.
Peroral Endoscopic Pyloromyotomy
Gastric antral hypomotility and pyloric dysfunction have been demonstrated in patients with idiopathic or diabetic nausea and vomiting. Hence, therapies eliminating the pyloric barrier may improve such symptoms in patients with gastroparesis. G-POEM is an incisionless, minimally invasive procedure analogous to POEM with proposed efficacy similar to surgical pyloroplasty. A mucosal incision is created 5 cm proximal to the pylorus either on the anterior or posterior wall. A submucosal tunnel is created to the level of the pyloric ring, which is then dissected. The mucosal incision is subsequently closed. Initial cases were performed by a surgical group in porcine models. Subsequently, the first human case was reported by Khashab and colleagues at Johns Hopkins Hospital. Another group of surgeons reported a series of 7 patients who had successful G-POEM; however, surgical laparoscopic guidance was also used in the majority (6/7) of patients, primarily because other laparoscopic interventions (cholecystectomy, fundoplication) were performed concomitantly. Overall clinical success rate approached 90%. Only 1 complication related to G-POEM has been reported; a patient who failed to take proton pump inhibitor after G-POEM presented with a bleeding pyloric channel ulcer with visible vessel, which was treated endoscopically. Chaves and colleagues and Gonzalez and colleagues have also reported successful G-POEM for refractory gastroparesis. Chung and colleagues reported a case of G-POEM for management of gastric outlet obstruction after esophagectomy.
G-POEM can safely be performed as a pure endoscopic procedure, provided the operator is experienced with the same skillset required for POEM. The current G-POEM operators have endoscopic and ESD experience and are expert POEM operators.
Submucosal Tunneling and Endoscopic Resection
Once new NOTES endoscopists became comfortable in the third space, the natural progression was resection of tumors residing beneath the mucosa in the esophagus and stomach. After creation of a mucosal incision, a submucosal tunnel is created, followed by enucleation of the tumor using ESD techniques while preserving the integrity of the overlying mucosa. The tumor is extracted via the mucosal incision that is, subsequently closed ( Fig. 3 ). Since 2012, more than 150 STER of medium sized lesions (19.5 mm) have been reported worldwide, contributed by both gastroenterologists and surgeons. Technical success (complete resection rate) is reported at 100% in large series with no recurrence at follow-up (range, 3.9–12 months). The most commonly reported adverse event was pneumothorax (26.6%), which was managed successfully with a chest drain. The modest rate of pneumothorax is likely related to (1) use of air insufflation rather than CO 2 in some early series and (2) requirement of full-thickness resection for tumors arising deep within the muscularis propria layer.
Related posts:
The New NOTES Expands Interventional Endoscopy
The New NOTES: More “E” and Less “S” Leads to Success!
Submucosal Tunneling Endoscopic Resection (STER) and Other Novel Applications of Submucosal Tunneling in Humans
Endoscopic Full-thickness Resection (EFTR) for Gastrointestinal Subepithelial Tumors
Hybrid NOTES
Pre-clinical Training for New Notes Procedures
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