Endoloop application as an alternative method for gastrotomy closure in experimental transgastric surgery

A New Era of Minimally Invasive Surgery: Progress and Development of Major Technical Innovations in General Surgery Over the Last Decade

Minimally invasive surgery (MIS) continues to play an important role in general surgery as an alternative to traditional open surgery as well as traditional laparoscopic techniques. Since the 1980s, technological advancement and innovation have seen surgical techniques in MIS rapidly grow as it is viewed as more desirable. MIS, which includes natural orifice transluminal endoscopic surgery (NOTES) and single-incision laparoscopic surgery (SILS), is less invasive and has better cosmetic results. The technological growth and adoption of NOTES and SILS by clinicians in the last decade has however not been uniform. We look at the differences in new developments and advancement in the different techniques in the last 10 years. We also aim to explain these differences as well as the implications in general surgery for the future.

Effects of gastric irrigation on bacterial counts before endoscopic submucosal dissection: a randomized case control prospective study

OBJECTIVE

The antiseptic effect of gastric irrigation before endoscopic submucosal dissection (ESD) has not yet been reported. The aim of the randomized prospective study is to evaluate the antiseptic effects of gastric irrigation of saline solution before ESD by evaluating bacterial count.

METHODS

This prospective randomized controlled trial included 50 patients diagnosed with early gastric cancer who were randomly divided into 2 groups (25 patients in each group) by using the opaque envelope method: the clean group (irrigation with 2 L saline solution before ESD) and the regular group (no irrigation). The gastric juice was collected and cultured before ESD. The entire stomach was irrigated using a water jet attached to an endoscope. After ESD with resection and removal of the tumor specimen, a postoperative culture of the gastric juice was obtained using the same method as the preoperative culture.

RESULTS

The mean log bacterial count of the post-gastric irrigation gastric juice was 5.08±0.75 in the regular group and 1.86±0.86 in the clean group. The difference in the bacterial counts was significant between the groups (P = 0.0004). The difference in the white blood cells (WBC) count on POD 1 was significant (P = 0.044). WBC count on POD 2 did not significantly differ between the groups (P = 0.3). The difference in the body temperature (BT) on POD 1 was significant (P = 0.017), On POD 2 the BT was not significant between the groups (P = 0.5). On POD 1, 88% of the patients in the regular group and 16% of the patients in the clean group had mild to moderate spontaneous pain (P = 0.0026). On POD 2 the proportion with mild to moderate spontaneous pain was 36% and 24% in the regular group and the clean group, respectively (P = 0.1).

CONCLUSION

Pre-ESD gastric irrigation with saline solution is effective and feasible for suppressing infection during the ESD procedure with favorable clinical outcomes. TRIAL REGISTRATION INFORMATION: The university hospital medical information network (UMIN) #000008691.

The Performance of Multiple Transgastric Procedures Using the Natural Orifice Transluminal Endoscopic Surgery Technique: Is Pure NOTES Satisfactory?

Background/Aims

Although several groups have demonstrated the usefulness of natural orifice transluminal endoscopic surgery (NOTES), there is still concern about frequent serious adverse events. We performed this study to determine the technical feasibility and safety of pure NOTES with a transgastric approach in a porcine model from the endoscopist's point of view.

Methods

Diagnostic peritoneoscopy, liver biopsy, salpingo-oophorectomy, and Fallopian tube ligation with a transgastric approach using a two-channel therapeutic endoscope were performed in 10 healthy female minipigs. These procedures were performed in two acute models and eight survival models in consecutive order.

Results

The technical success rate was 100% for peritoneoscopy (10/10), liver biopsy (5/5), salpingo-oophorectomy (10/10), and Fallopian tube ligation (10/10). Eight cases of adverse events occurred, including one case of splenic injury, one case of bleeding after liver biopsy, two cases of small bowel adhesion after salpingo-oophorectomy, two cases of hematoma at the salphingo-oophorectomy site, and two cases of partial dehiscence at the gastric closure site. The gastric puncture site was closed with seven to eight hemoclips in four cases and two hemoclips and an endoloop in four cases.

Conclusions

The use of pure NOTES for peritoneoscopy, liver biopsy, salpingo-oophorectomy, and Fallopian tube ligation may be technically feasible, but considerable adverse events can occur during or after the procedure. Further studies utilizing specialized techniques overcome several limitations of pure NOTES are therefore necessary.

An experimental study of betadine irrigation for preventing infection during the natural orifice transluminal endoscopic surgery (NOTES) procedure

OBJECTIVE

To study the effect and feasibility of using betadine irrigation of the gastrointestinal tract for preventing infection during the natural orifice transluminal endoscopic surgery (NOTES) procedure.

METHODS

Twelve sows were used in this study. Four sows in the control group were lavaged with 500 mL saline. The eight sows in the experimental group were first lavaged with 500 mL saline and then irrigated with 200 mL betadine. A total of 5 mL of gastrointestinal (GI) tract fluid was collected before and after lavage, respectively, and 5 mL of peritoneal fluid was collected at the end of the NOTES procedure. A follow-up endoscopic examination of the GI tract was performed 24 h after NOTES. The animals were killed and necropsied after 3 weeks.

RESULTS

Irrigation with betadine of the GI tract significantly reduced the bacterial load of GI fluid. One sow died of diaphragmatic injury. No inflammation, ulcer or bleeding were observed in the experimental group by endoscopy after 24 h. More adhesions and abscesses were found in the control group than in the experimental group after 3 weeks. Only one case of adhesion was observed in the experimental group using the transcolonic approach.

CONCLUSIONS

Betadine irrigation of the GI tract is effective and feasible for preventing infection during the NOTES procedure. Further studies are needed for assessing the effectiveness and safety of betadine irrigation in the clinical application of NOTES.

Natural orifice translumenal endoscopic surgery (NOTES(®)): a technical review

INTRODUCTION

The clinical NOTES literature continues to grow. This review quantifies the published human NOTES experience to date, examines instrument use in detail, and compiles available perioperative outcomes data.

METHODS

A PubMed search for all articles describing human NOTES cases was performed. All articles providing a technical description of procedures, excluding cases limited to diagnostic procedures, specimen extraction, fluid drainage or gynecological procedures, were reviewed. Two reviewers systematically cataloged the technical details of each procedure and performed a frequency analysis of instrument use in each type of case. Available outcomes data were also compiled.

RESULTS

Forty-three discrete articles were reviewed in detail, describing a total of 432 operations consisting of transvaginal (n = 355), transgastric (n = 58), transesophageal (n = 17), and transrectal (n = 2) procedures, with 90% of cases performed in hybrid fashion with laparoscopic assistance. Cholecystectomy (84% of cases) was the most common procedure. Analysis of key steps included choice of endoscope, establishment of peritoneal access, dissection, specimen extraction, and closure of the access site. Analysis of instrument use during transvaginal cholecystectomy revealed variation in the choice of endoscope and the technique for establishment of access. A majority of these procedures relied heavily on the use of rigid and transabdominal instrumentation. Closure of the vaginotomy site was found to be well standardized, performed with an open suturing technique. Similar analysis for transgastric procedures revealed consistency in the choice of flexible endoscope as well as access and closure techniques. Perioperative outcomes from NOTES procedures were reported, but the data are currently limited due to small case numbers.

CONCLUSIONS

NOTES is most commonly performed using a hybrid, transvaginal approach. Although some aspects of these procedures appear to be well standardized, there is still significant variability in technique. More outcomes data with standardized reporting are needed to determine the actual risks and benefits of NOTES.

Natural orifice translumenal endoscopic surgery (NOTES(®)): a technical review

INTRODUCTION

The clinical NOTES literature continues to grow. This review quantifies the published human NOTES experience to date, examines instrument use in detail, and compiles available perioperative outcomes data.

METHODS

A PubMed search for all articles describing human NOTES cases was performed. All articles providing a technical description of procedures, excluding cases limited to diagnostic procedures, specimen extraction, fluid drainage or gynecological procedures, were reviewed. Two reviewers systematically cataloged the technical details of each procedure and performed a frequency analysis of instrument use in each type of case. Available outcomes data were also compiled.

RESULTS

Forty-three discrete articles were reviewed in detail, describing a total of 432 operations consisting of transvaginal (n = 355), transgastric (n = 58), transesophageal (n = 17), and transrectal (n = 2) procedures, with 90% of cases performed in hybrid fashion with laparoscopic assistance. Cholecystectomy (84% of cases) was the most common procedure. Analysis of key steps included choice of endoscope, establishment of peritoneal access, dissection, specimen extraction, and closure of the access site. Analysis of instrument use during transvaginal cholecystectomy revealed variation in the choice of endoscope and the technique for establishment of access. A majority of these procedures relied heavily on the use of rigid and transabdominal instrumentation. Closure of the vaginotomy site was found to be well standardized, performed with an open suturing technique. Similar analysis for transgastric procedures revealed consistency in the choice of flexible endoscope as well as access and closure techniques. Perioperative outcomes from NOTES procedures were reported, but the data are currently limited due to small case numbers.

CONCLUSIONS

NOTES is most commonly performed using a hybrid, transvaginal approach. Although some aspects of these procedures appear to be well standardized, there is still significant variability in technique. More outcomes data with standardized reporting are needed to determine the actual risks and benefits of NOTES.

Closure of gastrotomy in natural orifice transluminal endoscopic surgery: a feasibility study using an ex vivo model comparing endoloop with endoclip

BACKGROUND

Closure of access site is one of the key issues that will determine the development of natural orifice transluminal endoscopic surgery. Our study was designed to compare the effectiveness of gastrotomy closure using endoloop and endoclip with hand-sewn closure as a control.

METHODS

Gastrotomy was carried out on 24 ex vivo porcine stomachs and the gastrotomies were randomized to be closed with either hand-sewn, endoloop or endoclip techniques. A 2 cm gastrotomy was created with a needle knife and sphincterotome and the defects closed thereafter. We measured the time to closure of gastrotomy and the pressure at which the closure leaked.

RESULTS

Three endoloops were required for all the closures in the endoloop group. In the endoclip group, the mean (range) number of endoclips used was 10 (8-13). There was no difference in the median closure times between endoloop 28 (16-58) min and endoclip 30 (21-40) min; however, time for hand-sewn closure was much shorter (3-5 min). All stomachs were successfully distended with air without leak at the end of the procedure and none experienced fluid leak. The endoclip closure endured a significantly higher median (range) pressure of 72.5 mmHg (15-80 mmHg) before leaking compared to that of an endoloop 25 mmHg (15-37 mmHg) (P < 0.001). The hand-sewn gastrotomy leaked at pressure of 95 mmHg (75-130 mmHg). The majority of air leaks were from the wound site. In the endoclip group, two leaks were noted at the clip bite site.

CONCLUSION

  In a bench-top model, endoclips seem to be better for gastrotomy closure because of their potential to endure relatively higher pressure without any prolongation of application time. Animal survival studies are needed to explore technical and wound-closure-related problems arising as a result of use of endoclips and endoloops for gastrotomy closure.

What are the elements of safe gastrotomy closure in NOTES? A systematic review

INTRODUCTION

The safe closure of the gastrotomy needs to be established before natural orifice translumenal endoscopic surgery (NOTES) can be extended to routine clinical practice. As yet no optimum closure method has been identified.

METHODS

A systematic review of the literature on gastrotomy closure modalities for NOTES up until December 2009 was undertaken. An assessment of each closure modality was determined using specified quantitative and qualitative parameters.

RESULTS

There were 46 studies included in this review describing 20 closure techniques. Some robustly designed experimental studies have now been published particularly in relation to the over-the-scope clip system.

CONCLUSION

Current evidence is experimental and therefore limited, but there appears to be some clarification in the direction of the innovative process in this area outlining favorable characteristics of an ideal system. Based on the studies examined in this review, a standardized assessment method is summarized for future in vivo studies, necessary prior to phase 1 trials.

Loop-Anchor Purse-String Closure of Gastrotomy in NOTES® Procedures: Survival Studies in a Porcine Model

Introduction: Transgastric NOTES® procedures remain without a simple method to close the gastrotomy. In four survival swine studies, we have tested a novel gastric closure device: the loop-anchor purse-string (LAPS) closure system. Methods: In four anesthetized pigs, an endoscopic gastrotomy was performed. Four loop anchors were arrayed in a 2-cm square pattern around the gastrotomy. The endoscope was passed into the abdominal cavity, and the gastrotomy was cinched closed. Results: Procedure times ranged from 50-180 minutes. Three pigs survived 14 days. One animal was sacrificed early due to signs of sepsis. Another animal developed fevers and was treated with antibiotics. At necropsy, there were no abscesses, including in the septic animal. Histologic examination revealed evidence of healing in all animals. Discussion: The LAPS system holds promise with early success in an animal model. Future human studies are needed to determine viability as a human visceral closure device.

Transgastric cholecystectomy: From the laboratory to clinical implementation

After the first report by Kalloo et al on transgastric peritoneoscopy in pigs, it rapidly became apparent that there was no room for an under-evaluated concept and blind adoption of an appealing (r)evolution in minimal access surgery. Systematic experimental work became mandatory before any translation to the clinical setting. Choice and management of the access site, techniques of dissection, exposure, retraction and tissue approximation-sealing were the basics that needed to be evaluated before considering any surgical procedure or study of the relevance of natural orifice transluminal endoscopic surgery (NOTES). After several years of testing in experimental labs, the revolutionary concept of NOTES, is now progressively being experimented on in clinical settings. In this paper the authors analyse the challenges, limitations and solutions to assess how to move from the lab to clinical implementation of transgastric endoscopic cholecystectomy.

Do gastrotomies require repair after endoscopic transgastric peritoneoscopy? A controlled study

BACKGROUND

The optimal method for closing gastrotomies after transgastric instrumentation has yet to be determined.

OBJECTIVE

To compare gastrotomy closure with endoscopically delivered bioabsorbable plugs with no closure.

DESIGN

Prospective, controlled study.

SETTING

Animal laboratory.

SUBJECTS

Twenty-three dogs undergoing endoscopic transgastric peritoneoscopy between July and August 2007.

INTERVENTIONS

Endoscopic anterior wall gastrotomies were performed with balloon dilation to allow passage of the endoscope into the peritoneal cavity. The plug group (n = 12) underwent endoscopic placement of a 4 x 6-cm bioabsorbable mesh plug in the perforation, whereas the no-treatment group (n = 11) did not. Animals underwent necropsy 2 weeks after the procedure.

MAIN OUTCOME MEASUREMENTS

Complications related to gastrotomy closure, gastric burst pressures, relationship of burst perforation to gastrotomy, and the degree of adhesions and inflammation at the gastrotomy site.

RESULTS

After the gastrotomy, all dogs survived without any complications. At necropsy, burst pressures were 77 +/- 11 mm Hg and 76 +/- 15 mm Hg (P = .9) in the plug group and no-treatment group, respectively. Perforations occurred at the site of the gastrotomy in 2 of 12 animals in the plug group and in none of the 11 dogs in the no-treatment group (P = .5). Finally, there were minimal adhesions in all dogs (11/11) in the no-treatment group and minimal adhesions in 3 and moderate adhesions or inflammatory masses in 9 of the 12 animals in the plug group (P = .004).

LIMITATIONS

Small number of subjects, animal model, no randomization. Gastrotomy trauma during short peritoneoscopy may not be applicable to longer procedures.

CONCLUSIONS

After endoscopic gastrotomy, animals that were left untreated did not show any clinical ill effects and demonstrated adequate healing, with fewer adhesions and less inflammation compared with those treated with a bioabsorbable plug.

Laparoscopic cholecystectomy combined using miniaturised instruments in transgastric gall bladder removal: performed on 63 patients

Background. The laparoscopic cholecystectomy is a perfectly codified surgical procedure. The development of recent innovative and experimental surgical techniques Natural Orifice transluminal endoscopic surger (N.O.T.E.S.) which reduces the abdominal wall trauma leads us to develop a combined procedure of a standard dissection using miniaturised instruments already existing on the market (3 and 5 mm wide) and a gall bladder removal through a short gastrotomy Natural Orifice Specimen Extraction (N.O.S.E.). Methods. Our objective was to evaluate the safety, the feasibility, and the reproducibility of our new approach. After reviewing existing products on the market and a feasibility study, we put in place a protocol in our structure for patients on whom the procedure was performed. We carried out a gall bladder removal by a short gastrotomy, located on the anterior gastric wall, which then reduced the abdominal wall trauma and allowed them to resume normal physical activity quickly without risk of trocar site hernia. Results. We performed the procedure described in this paper on 63 patients, between April 2008 and July 2009. There were 14 men and 49 women with an average age of 46.8 years (ranging from 28 to 77) and an average BMI of 27.2. 30 patients had at least one gallstone larger than 10 mm. There was no postoperative gastric or abdominal wall complication and a fast recovery for all the patients in our study. Conclusions. This procedure is feasible, reproducible, with good results and minimal abdominal wall trauma. It is also safer than N.O.T.E.S. and endoscopic clipping and recovery, allowing normal physical activity, fast and, without risk of incisional hernia.

Directed submucosal tunneling permits in-line endoscope positioning for transgastric natural orifice translumenal endoscopic surgery (NOTES)

BACKGROUND

Submucosal dissection is demonstrated to be a technically feasible, safe means of obtaining peroral transgastric peritoneal access for natural orifice translumenal endoscopic surgery (NOTES). The authors hypothesized that their previously described self-approximating translumenal access technique (STAT) could be used to create directed gastric submucosal tunnels permitting in-line endoscope positioning with predetermined abdominal locations that might otherwise be difficult to access.

METHODS

In this study, 14 domestic farm swine underwent peroral transgastric peritoneoscopy. Under direct endoscopic visualization, a submucosal tunnel was created by dissecting between the mucosal and muscular layers of the stomach. Each tunnel was created with one of four intraabdominal locations (right upper quadrant, left upper quadrant, lesser sac, and pelvis) as the final target for in-line endoscope positioning. Once peritoneal access had been achieved, in-line positioning was assessed and peritoneoscopy was performed. The submucosal tunnels were closed with endoscopically placed clips. The animals were killed 2 weeks after the procedure, and necropsy was performed.

RESULTS

Submucosal tunnels were successfully directed at predetermined intraabdominal targets in 12 of the 14 animals. The mean dissection time required to create the tunnel was 51 +/- 32 min. All the transgastric tunnels were successfully closed with endoscopically placed clips (mean, 3.2 +/- 1.1), and at necropsy showed no evidence of gastrotomy leak in any of the animals. One animal experienced a duodenal perforation unrelated to the transgastric tunneling and was killed on postoperative day 2. The remaining animals recovered and gained weight (mean, 5.5 +/- 1.2 kg) in the 2-week survival period.

CONCLUSIONS

Directed submucosal dissection is technically feasible in a porcine model and permits in-line endoscope positioning with predetermined abdominal target locations. The STAT approach provides safe peritoneal access, allows for a simple reliable endoclip closure, and has an excellent short-term survival rate. This method of achieving transgastric access may be an enabling technique for future NOTES procedures.

Natural orifice surgery (NOS)--toward a single-port transdouglas approach for intra-abdominal procedures

OBJECTIVE

To describe a future method for abdominal surgical procedures in women using a single-port Transdouglas Endoscopic Device (TED).

METHODS AND DESCRIPTION

The first successful laparotomy was performed in the 19th century, and the first endoscopic operation in the 20th century. The 21st century started with experimental operations using the natural body openings. Various abdominal procedures have already been performed through the stomach, but it seems that the transdouglas pathway in women is the most promising access into the peritoneal cavity, for its safety and cost-effectiveness. The TED is designed to perform operations in the upper and the lower abdomen. The New European Surgical Academy (NESA) founded the first European based interdisciplinary working group in order to plan and design instruments toward future gynaecological, urological and surgical applications.

CONCLUSION

The single-port TED is expected to replace many of today's endoscopic procedures due to its probably higher safety and better ergonomics.

NOTES: new dimension of minimally invasive surgery

Natural orifice transluminal endoscopic surgery (NOTES) is an emerging experimental alternative to conventional surgery. NOTES eliminates abdominal incisions and incision-related complications by combining endoscopic and laparoscopic techniques to diagnose and treat abdominal pathology. Since the first NOTES was reported by Kalloo et al. in 2004, significant achievements in the laboratory have occurred. Clinical use in humans has been limited, but several cases and one small clinical trial were published recently. As a further technical revolution in minimally invasive surgery, NOTES has the promising potential to be safer, less invasive, provide better cosmesis and possibly be more cost-effective. The purpose of the present article was to review the development and current status of NOTES and highlight important advances associated with this innovative approach.

Natural orifice translumenal endoscopic surgery 2009: what is the future for the gastroenterologist?

PURPOSE OF REVIEW

In order to predict whether the gastroenterologist will have a role in the rapidly developing field of natural orifice translumenal endoscopic surgery (NOTES), it is helpful to examine the new developments in this field. Our goal in this review is to examine the recent developments in the field and study the gastroenterologists' role to best make this prediction.

RECENT FINDINGS

Perhaps the most significant development in the field of NOTES has been the favorable patient and physician preferences for NOTES. There is evidence that patients would prefer NOTES cholecystectomy to laparoscopic cholecystectomy. The most common reason for this choice appears to be the lack of pain and visible scar. Another very significant development has been the reality of human NOTES procedures. Multiple centers have reported human NOTES procedures, including transgastric appendectomies, transgastric liver biopsies, transgastric tubal ligation and transvaginal cholecystectomy without major complications. Gastroenterologists' expertise with flexible endoscope was critical in the above cases. Recently, a few publications have also shown how gastroenterologists with expertise in endosonography can have a role in affirming safe access.

SUMMARY

Although no one can predict with certainty where the field of NOTES will be in 1 year, it seems likely that gastroenterologist involvement will be necessary and advancements in this field will be applicable and diffuse into our daily practice.

N.O.T.E.S.: the progression of a novel and emerging technique

Natural Orifice Transluminal Endoscopic Surgery (NOTES) is the latest and perhaps most significant innovation in surgery since Phillipe Mouret of France performed the first laparoscopic cholecystectomy in 1987. This new "minimum-invasive" concept that promises scar-free surgery is steadily gathering momentum. It is another milestone in our quest to eliminate surgical trauma, speed patient recovery time and decrease surgical wound-related complications. On 22 July 2005, the Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR) published a white paper highlighting the barriers to NOTES development, which included the need for appropriate selection of access points, effective closure of the enterotomy site, innovative tools, stable platforms and improved endoscopic orientation. These are just some of the many issues that need to be resolved before the NOTES concept and technique could become a common feature of modern surgery. The publication of the white paper ushered in the beginning of multiple research projects using animal models to test the application of NOTES and its newly developed instruments. The success in animal models was followed by several highly selected successful human trials. National and international surgical innovation departments should now be created where medical industry personnel including inventors, designers and engineers can work together with the medical and surgical providers to address all the limitations affecting NOTES progress.

Comparison of transgastric access techniques for natural orifice transluminal endoscopic surgery

BACKGROUND

Different transgastric access techniques for natural orifice transluminal endoscopic surgery (NOTES) have been described.

OBJECTIVE

To evaluate different methods of transluminal access with regard to leak pressures after the procedure.

DESIGN AND SETTING

Experimental endoscopic study in an ex vivo porcine stomach model.

METHODS

The following endoscopic techniques for transgastric access were evaluated in 34 stomachs: (1) 1.5-cm to 2-cm linear incision, (2) balloon dilation after needle-knife puncture, (3) via a short submucosal tunnel, and (4) via an extended submucosal tunnel. For techniques 3 and 4, a submucosal tract was endoscopically created by physically separating the mucosa from the muscularis. Mucosal incisions were closed by the standardized application of clips. Handsewn gastric closure after a linear needle-knife incision served as a positive control, whereas, open 1.5-cm to 2-cm gastrotomies were negative controls. After the procedure, pressures to liquid leakage were recorded.

RESULTS

The unclosed controls demonstrated leakage at mean (SD) 2 +/- 2 mm Hg, which represents a baseline system resistance. The handsewn gastric closure after linear incision leaked at 50 +/- 7 mm Hg. The needle-knife gastrotomy, the balloon dilation, the short submucosal tunnel, and the extended submucosal tunnel leaked at 37 +/- 15 mm Hg, 41 +/- 24 mm Hg, 44 +/- 13 mm Hg, and 87 +/- 19 mm Hg, respectively. There were significant differences in leakage pressures between the group with the extended submucosal tunnel and all other transgastric access techniques (all P < or = .002).

CONCLUSIONS

The extended submucosal tunnel yielded the best leak resistance, which is superior to standard transgastric access methods and rival handsewn interrupted stitches.

The eagle or the snake: platforms for NOTES and radical endoscopic therapy

It has only been about 3 years since natural orifice translumenal endoscopic surgery (NOTES) first began to gather the attention of the medical and surgical community at large. The concepts behind NOTES, however, have been under development for almost a decade. It is important to revisit some basic concepts regarding therapeutic flexible endoscopy and in the process understand the fundamental premises on which a sound technology development program for NOTES should be built. This article provides such a review and emphasizes general principles rather than specific embodiments, which are very much at a nascent stage.