Natural Orifice Translumenal Endoscopic Surgery - State of Research

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 recently 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.

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.