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a “submucosal tunnel” to the upper quadrant and utilization of a multibending endoscope, these authors were able to suc- cessfully perform transgastric NOTES cholecystectomies in four porcine models.

In addition to lack of rigidity, flexible endoscopic shafts also limit the force that can be applied to retract tissue. A variety of methods to provide retraction of the gallbladder using transabdominal stay sutures, clips or magnets that can be manipulated through the skin have been reported.29–31 Ryou and Thompson utilized an external magnetic assembly clamped to the edge of the operating table which was able to retract tissue after internal magnets were attached to the tissue using endoscopic clips.29 The clips were deployed in serial fashion along the inferior edge of the hepatic lobes in order to lift the hepatic lobes and expose the gallblad- der. Despite minor trauma to the liver, the gallbladder was fully exposed in four of the five porcine models studied. The procedure time was shortened by 27% when magnets were used. Note, thicker abdominal walls or manipulation of targets more centrally located in the peritoneal cavity would require extremely powerful magnetic systems and patients with pacemakers, metal foreign bodies or recently implanted metal orthopedic prostheses may pose a potential contraindication.

As with all new technology in its infancy, most NOTES platforms are prototypes and suboptimal. Consensus as to whether the “ideal” NOTES platform will be a flexible endoscope alone, a multilumen overtube, a complex robotic system or a combination of these remains unknown.

Karimyan et al reviewed 5 separate navigational plat- forms, including 3 robotic systems, which are currently being developed for NOTES procedures.32 These authors evalu- ated the devices based on size, image quality, insufflation ease, suction/irrigation ease, maneuverability, stability, and ability to provide triangulation. They found no system uniquely superior to all others and surmised that significant improvements were needed. These authors also stressed that once an “ideal” platform for NOTES is available, and it may not be just one, an ongoing “give and take” between surgeons and engineers is necessary to further mature this new technology.

ethical and training challenges of NOTeS

Before “incisionless” surgery, that is NOTES, becomes rapidly adopted, a robust discussion concerning the ethics of NOTES must ensue. Although the transvaginal route is currently deemed a safe approach for avoiding iatrogenic injury, no studies have evaluated the potential for future

Open Access Surgery 2010:3

Techniques and challenges of NOTeS cholecystectomy

fertility issues, dyspareunia, vaginal cuff dehiscence, or bowel herniation.7,33 Lacking this important information, it is imperative that the informed consent process, as with all investigational procedures, be comprehensive, honest, and robust. Given our present inability to point to any significant clinical advantages to NOTES over traditional laparoscopic surgery or SILS, an on-going open discussion regarding the ethics of NOTES should proceed in parallel with its development.

Whether NOTES becomes a mainstream surgical proce- dure or is limited to select centers is unclear. Given the cur- rent limitations, and the limited number of general surgeons well-trained in flexible endoscopy, broad applicability of NOTES seems unlikely except in the case of transvaginal approaches for select women. Once a reliable NOTES plat- form exists, extensive efforts at training and reeducation will be necessary if this procedure is to be safely performed. Given the perceived steep learning curve for the average general surgeon possessing limited flexible endoscopy credibility, virtual reality, and computer-based systems with immedi- ate feedback and performance analysis will be necessary to develop a proficient simulator and permit credibility for this technology.34 Moreover, NOTES will ultimately expand the field of general surgery, gastroenterology or result in a new “hybrid” specialty is as of yet unclear.

Patient selection criteria for NOTeS

If we are to develop NOTES technology safely it must pro- ceed in a gradual fashion. As such, these procedures should be limited to “ideal candidates” who pose low procedural complication risks. While no comprehensive patient selec- tion criteria has been published to date, most investigators have selected patients for NOTES cholecystectomy who are: (1) thin (BMI , 35), (2) have no evidence of acute cholecystitis, (3) have had no prior abdominal or pelvic surgeries, and (4) who have no history or current symptoms of endometriosis or pelvic inflammatory disease.33,35 When you also consider the fact that .90% of all published NOTES cholecystectomy have been performed via the transvaginal route, and that women who have had endometriosis, cesar- ean section, pelvic/vaginal or abdominal surgery, or pelvic inflammatory disease are excluded, the size of the potential NOTES cholecystectomy candidate pool seems quite small. Although patient selection criteria for NOTES will certainly become less stringent with experience, it will no doubt remain a procedure for a small number of informed patients rather than for the general population. Although, some have advo- cated that sicker patients who are not suitable for laparoscopic

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