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Natural orifice transluminal endoscopic surgery (NOTES) is an experimental surgical technique whereby "scarless" abdominal operations can be performed with an endoscope passed through a natural orifice (mouth, urethra, anus, etc.) then through an internal incision in the stomach, vagina, bladder or colon, thus avoiding any external incisions or scars.
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State of research
This technique has been used for diagnostic and therapeutic procedures in animal models, including transgastric (through the stomach) organ removal. Most recently, the transvesical and the transcolonic approaches have been advocated by some researchers as being more suited to access upper abdominal structures that are often more difficult to work with using a transgastric approach. In this sequence, a group from Portugal used transgastric and transvesical combined approach to increase the feasibility of moderately complex procedures such as cholecystectomy. NOTES was originally described in animals by researchers at Johns Hopkins University (Dr. Anthony Kalloo et al.), and was once upon a time used for transgastric appendectomy in humans in India (by Drs. G.V. Rao and N. Reddy). On June 25, 2007 Swanstrom and colleagues reported the first human transgastric cholecystectomy. Totally transvaginal cholecystectomy has been described in experimental model without using laparoscopic assistance. In late 2008 surgeons from Johns Hopkins School of Medicine removed a healthy kidney from a woman donor using NOTES. The surgery was called transvaginal donor kidney extraction.
The transvaginal access to NOTES seems to be the most safe and feasible for clinical application. In early March 2007, the NOTES Research Group in Rio de Janeiro, Brazil, led by Dr. Ricardo Zorron, performed the first series of transvaginal NOTES cholecystectomy in four patients, based in previous experimental studies. With fewer potential complications, the procedure has a disadvantage of being possible only in women.
Proponents and researchers in this field recognize the potential of this technique to revolutionize the field of minimally invasive surgery by eliminating abdominal incisions. NOTES could be the next major paradigm shift in surgery, just as laparoscopy was the major paradigm shift during the 1980s and 1990s. Potential advantages include lower anesthesia requirements; faster recovery and shorter hospital stays; avoidance of the potential complications of transabdominal wound infections (e.g. hernias); less immunosuppression; better postoperative pulmonary and diaphragmantic function; and the potential for "scarless" abdominal surgery. Critics challenge the safety and advantages of this technique in the face of effective minimally invasive surgical options such as laparoscopic surgery. However, research continues in addressing the critical access challenge. Proposed solutions include the use of permanent magnets.
Unlike laparoscopy, which was treated with much disdain as a passing fad by most nationally recognized academic institutions, NOTES is being embraced by several universities nationally. The general impression is that NOTES, or a derivative of its technology will be accepted as the newest frontier in minimally invasive surgery. As of today non-bariatric minimally invasive surgery fellowships offer the best opportunity to train in this new approach. However, a systematized training model to translate these procedures to the clinical practice in a safe way is needed.
The use of flexible endoscopes results in a partial loss of spatial orientation and depth perception. This is a potential barrier especially for surgeons who are trained to rigid laparoscopes. So research of engineers focuses on computer assisted imaging systems that provide additional 3-D information of the intervention site. Virtual off-axis view assists surgeons with a better visual depth perception during the intervention. Other approaches keep a stable horizon in order to enhance spatial orientation during the intervention. Video images can be rectified using the impact of gravity on a 3-axis accelerometer integrated in the tip of the endoscope.
More recently, transoral thyroidectomy has been described, and is being completed with success in Thailand, South Korea, and highly specialized centers such as Johns Hopkins in the United States.
NOSCAR
Senior leadership from the American Society for Gastrointestinal Endoscopy (ASGE) and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) organized a working group of surgeons and gastroenterologists in 2006 to develop standards for the practice of this emerging technique. This group is known as the Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR). A White Paper on NOTES was released by NOSCAR simultaneously in two medical journals in May 2006. This paper identified the major areas of research needed to be addressed before NOTES can become a viable clinical application for human patient. These areas included development of a reliable closure technique for the internal incision, prevention of infection, and creation of advanced endoscopic surgical tools.
NOTES as defined by the NOSCAR group stands for "Natural Orifice Translumenal Endoscopic Surgery". This describes going beyond the margins of a lumen (=hollow organ). There is a controversy about the correct spelling of "translumenal" in NOTES whether with a terminal "e" or an "i". Even if both forms (lumenal/luminal) are used, the "i" is probably more correct. Analogies are found with nomen, foramen or abdomen which build the corresponding adjective form with an "i" (nominal, foraminal, abdominal).
NESA / NOS
Parallel to the NOTES (Natural Orifice Translumenal Endoscopic Surgery) working group which looks beyond existing horizons and concentrates on the transgastric peritoneal access, the New European Surgical Academy (NESA) founded the NOS (Natural Orifice Surgery) working group which is exploring another surgical route, the transdouglas one.
The term difference is not accidental. T in NOTES stands for transluminal. NOS includes NOTES because it refers to all surgical procedures performed through natural openings like mouth, nose, urethra and vagina.
The NESA designed a new surgical device, the Transdouglas Endoscopic Device (TED) adapted to female pelvic anatomy. The TED is a wide multi-channel flexible instrument enabling surgical procedures in the upper abdomen (cholecystectomy, liver biopsy, splenectomy etc.) as well as in the pelvis (hysterectomy, cystectomy, etc.) by using a single entry. See Pouch of Douglas.
The members of the European NOS working group are internationally renowned scientists, physiologists, pharmacologists and surgeons from various disciplines. The first meeting was on June 23, 2006, in Berlin. The planned procedures have already been simulated and preclinical studies will start soon. The NESA strongly believes that in the future, this new approach using the body natural openings and "traditional" endoscopic operations will complement each other.