Technical complications encountered during NOTES have revealed that there is a need for new endoscopic instruments, in order to safely perform these procedures.

Initially published papers led to believe that NOTES would be done primarily as transgastric procedures. However, peritoneal cavity could safely be accessed through a variety of other transluminal routes. Gynecologists had been accessing pelvic organs transvaginally since the early twentieth century. In fact, the first transvaginal cholecystectomy had been performed by Tsin et al. long before the White Paper by NOSCAR [12]. Currently most human NOTES procedures use transvaginal access since this route is well established and vaginal closure is safe, secure, and easy to perform. On the other hand, transgastric access still seems to be a better approach as it is more universally available than transvaginal and often more appealing to the patients. However, despite the availability of variety of closure devices and techniques, endo-luminal method of determining closure security at the end of a transgastric or transrectal procedure remains an unresolved issue.

Transvaginal NOTES access devices have been initially reported on by Gettman et al. [13]. In their technique following a posterior colpotomy, modified 24–30F dilators were inserted over a 24F dilating balloon as access ports. Further reports, including the first reported transvaginal cholecystectomy in the USA, either used standard laparoscopic ports (12 or 15 mm) or rigid ports with outer diameter between 21 and 26 mm as transvaginal access sites into the abdomen. Clayman et al. performed hybrid nephrectomy in a porcine model using the most novel system [14]. Furthermore, 12 mm laparoscopic ports were used for both transcolonic and transvesical access.

However, NOTES without any laparoscopic assistance have not been achieved yet. Limitations of technology for the access still need further development in instrumentations. Therefore, the ideal matchup between access, pathology, and patient preference has yet to be determined.

In addition to the access, there are still some other limitations in current NOTES instrumentation, including minimal traction-countertraction that is required. In order to overcome these limitations, multitasking endoscopic platforms and new instruments have been developed and used to achieve better triangulation with promising results. Magnetic anchoring and guidance system (MAGS) has been used widely to facilitate especially single-port NOTES-assisted nephrectomies [15]. Multitasking platforms such as TransPort^® (USGI Medical San Clemente, CA), Cobra™ (USGI Medical, San Clemente, CA), R-scope (XGIF-2TQ160R; Olympus Corp, Tokyo, Japan), the Endo-SAMURAI™ (Olympus Corp, Tokyo, Japan), and the Direct Drive Endoscopic System (DDES) (Boston Scientific, Natick, MA) each have a common flexible endoscopic design with some differences on channel system, motion, angulations, and suturing being used [16–20].

NOTES still has some unresolved issues identified and published by working group of NOSCAR, including access, closure, devices, spatial orientation, etc. as shown in Table 32.1.

Many different access routes to peritoneal cavity including transgastric, transvesical, transcolonic, transvaginal, and combined have been described. Main access routes in humans are transvaginal and followed by transgastric, transesophageal, and transrectal, respectively [24–26]. The transgastric approach requires creation and dilatation of a hole on the anterior stomach wall for the introduction of the operating platform. Therefore, there is a certain level of risk of bleeding, leak, or injuring the adjacent organs or tissues. In order to decrease the risk, some devices, such as endoscopic ultrasound, have been reported to be used but its efficacy needs to be evaluated in humans [27].