Natural orifice translumenal endoscopic surgery (NOTES) experimental evolution

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Editor-In-Chief: Mohammed A. Sbeih, M.D. [mailto:msbeih@perfuse.org] Phone:617-849-2629

Synonyms and keywords: Natural orifice translumenal endoscopic surgery, Single incision laparoscopic surgery, Minimally invasive surgery, Transanal endoscopic microsurgery, Natural orifice surgery consortium for assessment and research, Society of american gastrointestinal and endoscopic surgeons.

Natural Orifice Translumenal Endoscopic Surgery (NOTES) Experimental Evolution
The fields of gastrointestinal surgery and interventional endoscopy are converging since the advent of the interventional endoscopic therapy field. Gastroenterologists and therapeutic endoscopists have started performing more invasive interventions than before. Recently, they have started to manage cases that was managed only surgically. In the other hand, surgical interventions in the abdominal, peritoneal, and thoracic cavities have become less invasive than before and a new minimally invasive surgical methods have been invented to minimize trauma. The evolving concept of natural orifice translumenal endoscopic surgery (NOTES) combines the techniques of minimally invasive surgery with flexible endoscopy. This permits performing certain procedures endoscopically by passing the endoscope and the surgical instruments through a natural orifice, then transluminally into areas that would not otherwise be accessible endoscopically. A successful transgastric gastrojejunostomy procedure in a porcine survival model (a long-term survival) was an important step in proving that NOTES maybe feasible; it demonstrated that basic techniques in surgery such as organ removal and anastomoses could be performed via natural orifices.

In the late 1990s, a multicenter team of investigators (the Apollo Group) developed the concept of flexible transluminal endoscopy (a term used before NOTES). The first published report of a true transluminal procedure in 2004 by Kalloo et al has demonstrated the possibilities of penetrating the gastric wall and operating in animal model using a perorally introduced flexible endoscope. NOTES procedures moved quickly from a concept to clinical trials on humans based on many preclinical studies. These studies have demonstrated that several types of NOTES operations can be performed in animal survival models and human cadavers. Puncturing one of the viscera to perform NOTES procedures leaded to many questions regarding the infectious complications and the reliable incisional closure. Many clinical trials have been tried to answer these questions before proceeding to clinical NOTES.

NOTES procedures have been expanded in the last few years to cover a wide range of complex surgical operations by using the right translumenal route, endoscopic platform and the suitable instrumentation. Initially and over the last few years, endoscopic access to the peritoneal cavity using transoral (transgastric) route has been intensely investigated to perform various abdominal procedures, these procedures include cholecystectomy, appendectomy, splenectomy , ligation of fallopian tubes , gastrojejunostomy , peritoneal exploration and organ resection , lymphadenectomy , partial hysterectomy , oophorectomy , interventions on pelvic organs and other abdominal procedures. Recently, alternate access routes for NOTES procedures have been investigated such as transvaginal, transesophageal, transcolonic/transanal and transvesical/transurethral routs. The most rapidly evolved experimental studies were transvaginal NOTES procedures, including cholecystectomy, nephrectomy and appendectomy , and the first human case was described in 2007. Cholecystectomy, which is a high volume and relatively simple end organ operation, has been the focus of most early NOTES research studies. Recently, NOTES approach has been extended from the peritoneum to other body compartments such as the thoracic cavity (mediastinum, heart and lung) through a transesophageal approach. Other recent animal studies have been focused on transgastric intrauterine procedures.

NOTES has also inspired the development of new and novel instrumentation and innovative surgical techniques for minimally invasive and endoscopic procedures. Gergard Buess (from Germany) introduced in the 1980s the Transanal Endoscopic Microsurgery (TEM), a natural orifice procedure used for full-thickness resection of rectal tumours followed by suture closure of the resultant defect. TEM fulfils most requirements for the ideal NOTES operating platform based on what was published in NOSCAR white paper. TEM provides stable base, suction, irrigation, multiple working ports, pneumoperitoneum maintainance, and the capacity to close the viscotomy.

Recently, Robotic surgery has been investigated to be applied in NOTES procedures, a miniature in vivo robot has been developed for NOTES. The robot can be advanced through the esophagus into the peritoneal cavity. The robot may provide a stable platform for visualization and manipulation. This has been tested in a porcine model as well.

Investigators are trying to eliminate the laparoscopic component of NOTES procedures in order to perform them through the natural orifices only without any laparoscopic assistance or guidance.