natural orifice translumenal endoscopic surgery...

Can J Gastroenterol Vol 21 No 7 July 2007 423

Natural orifice translumenal endoscopic surgery(NOTES): What are we getting into?

Lawrence C Hookey MD1, Randy Ellis PhD2

1Division of Gastroenterology; 2School of Computing, Department of Mechanical and Materials Engineering, Department of Surgery, Hotel DieuHospital, Kingston, Ontario

Correspondence: Dr Lawrence C Hookey, Queen's University, Division of Gastroenterology, Hotel Dieu Hospital, 166 Brock Street, Kingston,Ontario K7L 5G2. Telephone 613-544-3310, fax 613-544-3114, e-mail [email protected]

WHAT IS NATURAL ORIFICE TRANSLUMENAL

ENDOSCOPIC SURGERY?For most gastroenterologists, one of the first rules of endoscopyis to diligently avoid perforation of the gastrointestinallumen. While this principle remains true in the majority ofcases, therapeutic crossing of the gastric or duodenal lumen isnow accepted for pancreatic pseudocystdrainage and percutaneous gastrostomy tubeplacement. Endoscopic ultrasound-guided fineneedle aspiration of abnormalities in theabdomen and mediastinum has further pushedthis barrier. Natural orifice translumenal endo-scopic surgery (NOTES), first described in 2004(1), extends the concept of extraluminal endo-scopic intervention to another level. The tech-nique begins with the creation of an opening ina natural lumen (most often gastric, althoughcolonic, vesical, vaginal and uterine approacheshave been described) using either electrosurgi-cal incision or needle puncture followed by bal-loon dilation. An endoscope is then passedthrough the opening, with pneumoperitoneumprovided through the endoscope. Proceduressuch as cholecystectomy and oophorectomy areperformed using traditional (snares, biopsy for-ceps, endo-loops) and nontraditional (endoscopic suturingdevices) endoscopic equipment. Upon withdrawal of the endo-scope back into the lumen, the wall defect is closed using clipsor sutures. Although most work has been limited to animalexperiments (most commonly pigs), Drs Reddy and Rao, fromthe Asian Institute of Gastroenterology in Hyderabad, India,have performed a limited number of transgastric appendec-tomies in humans (personal communication).

The main potential advantages of NOTES are related tothe lack of transabdominal incisions. This could possiblyreduce anesthetic requirements and postoperative pain, lead-ing to faster recovery. The lack of restricted inspiration sec-ondary to abdominal wall pain could potentially lead to alower rate of postoperative atelectasis and pneumonia. Inaddition, patients who traditionally have poorer outcomeswith open surgery (those with chronic obstructive pulmonarydisease, the morbidly obese, corticosteroid users) may be par-ticularly suited to NOTES, with its potential for easier accessto the peritoneum and decreased postoperative recovery.The cosmetic advantage of NOTES, or ‘scarless surgery’, isobvious. However, the importance of this is still debated (2)

and the significance that patients would place on thisremains to be determined.

MAIN CHALLENGESThe field of NOTES is evolving at a rapid pace but substantialchallenges still exist before its translation to use in humans can

be considered. Infection remains a primary con-cern. For transgastric procedures, the instru-ments are passed through the mouth, with itsmultitude of organisms, and then through thestomach into a sterile field – the peritoneum.Overtubes and gastric lavage with antibioticsolutions have been used in an attempt toreduce infection rates, but their efficacy has yetto be clarified (3,4).

While in the peritoneum, orientation can bea challenge, because the triangulation used bysurgeons during laparoscopy is not possible.Some organs appear relatively easy to find, suchas the uterus and ovaries, while others are some-what surprisingly difficult to localize (gallblad-der, spleen) (5). Potential solutions mayinvolve spatial orientation devices, or preoper-ative computed tomography scans with real-time reconstruction imaging. The flexibility of

the endoscope, usually its advantage, can lead to difficultiesduring intraperitoneal procedures. Another problem encoun-tered in early studies is control of the intraperitoneal pressurefrom insufflation, which in some cases has become too highand decreased perfusion to vital organs, requiring decompres-sion via a transabdominal needle. However, the biggest chal-lenge thus far is consistent, safe closure of the defect in thelumen wall. Accordingly, this is also one the most intense areasof research and development. Several techniques have beendeveloped and are being assessed currently, using various meth-ods of clips and sutures (1,4-7).

FIELDS OF INTEREST/INDICATIONSNumerous surgeries have been performed via NOTES,including cholecystectomy, oophorectomy, hysterectomy,splenectomy, appendectomy and gastrojejunostomy. Most ofthese have thus far been feasibility studies, without a true viewat comparing outcomes, but research is now moving in thatdirection, with survival studies being reported and randomizedtrials starting soon. In 2005, a working group involving theAmerican Society of Gastrointestinal Endoscopy and the

CURRENT ENDOSCOPIC PRACTICES – THE EXPERTS SPEAK

©2007 Pulsus Group Inc. All rights reserved

Lawrence C Hookey

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Society of American Gastrointestinal Endoscopic Surgeonswas created to discuss NOTES, to share experiences and todevelop a plan for future research. This group, named theNatural Orifice Surgery Consortium for Assessment andResearch, produced a white paper identifying critical areas to beresolved with future research (5). The group also highlightedthe need for a multidisciplinary approach to this field, includ-ing members with laparoscopic expertise (surgeons) and flexi-ble endoscopy expertise (gastroenterologists). In addition, theworking group agreed that all members would limit research toanimal models, ie, no human studies, until certain agreed uponstandards are met, and that all subsequent human proceduresbe performed under the approval of institutional researchethics boards, as well as placed in a central registry. This work-ing group now has regular research meetings and has adoptedthe acronym NOSCAR. The organization has established acompetitive grant award system and recently awarded nearlyone million dollars in research funding.

QUEEN’S UNIVERSITY GASTROINTESTINAL

DISEASES RESEARCH UNIT (GIDRU) NOTES

LABORATORYWe are in the process of establishing a multidisciplinaryNOTES laboratory, which is, to my knowledge, the first inCanada. We have a team of gastroenterologists, general sur-geons, gastrointestinal pathologists and a computer scienceimage modeling expert. Our initial goals are to develop afamiliarity with the technique of transgastric and trans-colonic passage of the endoscope, combined with simple pro-cedures (tubal ligation/oophorectomy, appendectomy). Wethen plan to focus on specific hypothesis-driven experimentsassessing the role of gastric decontamination, various gastricopening and closure techniques, the benefit of preoperativecomputed tomography with intraoperative computer-assistedpositioning (8), and the potential for endoscopic ultrasoundto assess lesions beyond the traditional reach of the instru-ment. We intend to abide by the white paper recommenda-tions (5) and limit our research to ethics board-approvedanimal experiments until near perfection in these techniqueshas been obtained.

CONCLUSIONNOTES is an exciting field that is clearly pushing the bound-aries of endoscopy as we know it. Although the procedure inits current form has only moderate benefits over laparoscopicsurgery, it is possible that further research will reveal an as yetundiscovered niche. When I speak to surgeons about NOTES,skepticism is frequently expressed but it is always qualified withanecdotes about laparoscopic surgery in the early days; very fewpeople thought it had a role in the future of surgery, yet it hasbecome a mainstay and increasingly more surgeries are beingperformed using this technique. I believe that skepticism ishealthy, and NOTES should be approached in a scientificfashion with an aim to answer questions through hypothesis-driven experiments. Whatever the future of NOTES, currentand future research is sure to have the spinoff benefit ofadvances in intraluminal endoscopy.

REFERENCES1. Kalloo AN, Singh VK, Jagannath SB, et al. Flexible transgastric

peritoneoscopy: A novel approach to diagnostic and therapeuticinterventions in the peritoneal cavity. Gastrointest Endosc2004;60:114-7.

2. Swain P. A justification for NOTES – Natural orifice translumenalendosurgery. Gastrointest Endosc 2007;65:514-6.

3. Jagannath SB, Kantsevoy SV, Vaughn CA, et al. Peroraltransgastric endoscopic ligation of fallopian tubes with long-termsurvival in a porcine model. Gastrointest Endosc 2005;61:449-53.

4. Merrifield BF, Wagh MS, Thompson CC. Peroral transgastric organresection: A feasibility study in pigs. Gastrointest Endosc2006;63:693-7.

5. ASGE, SAGES. ASGE/SAGES Working Group on NaturalOrifice Translumenal Endoscopic Surgery White Paper October2005. Gastrointest Endosc 2006;63:199-203.

6. Kantsevoy SV, Jagannath SB, Niiyama H, et al. Endoscopicgastrojejunostomy with survival in a porcine model. GastrointestEndosc 2005;62:287-92.

7. Wagh MS, Merrifield BF, Thompson CC. Survival studies afterendoscopic transgastric oophorectomy and tubectomy in a porcinemodel. Gastrointest Endosc 2006;63:473-8.

8. Vosburgh KG, Stylopoulos N, Estepar RS, Ellis RE, Samset E,Thompson CC. EUS with CT improves efficiency and structureidentification over conventional EUS. Gastrointest Endosc2007;65:866-70.

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