The challenges with NOTES retroperitoneal access in humans

On the suitability of Thiel cadavers for natural orifice transluminal endoscopic surgery (NOTES): surgical training, feasibility studies, and anatomical education

BACKGROUND

Surgical training in virtual, animal and cadaver models is essential for minimally invasive surgery. Thiel cadavers are suitable for laparoscopy, but there are few data about the use of embalmed (Tutsch method) and slightly embalmed (Thiel method) cadavers in procedures of Natural Orifice Transluminal Endoscopic Surgery (NOTES), which are usually developed and learned on swine models and fresh frozen cadavers. The aim of this study was thus to assess the use of these cadavers for NOTES approaches.

METHODS

The following surgical procedures were evaluated: transanal total mesorectal excision (four cadavers: one Tutsch, two Thiel, one fresh frozen), transanal ileorectal bypass (five cadavers: one Tutsch, three Thiel, one fresh frozen), and transvaginal appendectomy (two Tutsch cadaver).

RESULTS

The Thiel method ensured tissue flexibility and consistency suitable for performing the above surgical procedures with good results and without complications, with only a small increase in rigidity with respect to fresh specimens. Cadavers embalmed with higher formalin concentrations (Tutsch method) were more difficult to use, due to high tissue rigidity and resistance of the abdominal wall to pneumoperitoneum, although NOTES accesses were possible.

CONCLUSIONS

Thiel cadavers are suitable for transanal/transrectal and transvaginal NOTES approaches, for training surgical residents/specialists and also for surgical research. In minimally invasive surgery (and particularly in NOTES), integration between cadaver (fresh frozen and/or Thiel) and animal models would represent the gold standard, allowing guaranteed knowledge of and respect for human surgical anatomy and correct management of surgery on living subjects. NOTES approaches to human cadavers may also be proposed for the anatomical education of medical students.

Natural orifice transluminal endoscopic surgery for intra-abdominal emergency conditions

BACKGROUND

Patient benefits from natural orifice transluminal endoscopic surgery (NOTES) are of interest in acute-care surgery. This review provides an overview of the historical development of NOTES procedures, and addresses their current uses and limitations for intra-abdominal emergency conditions.

METHODS

A PubMed search was carried out for articles describing NOTES approaches for appendicectomy, percutaneous gastrostomy, hollow viscus perforation and pancreatic necrosectomy. Pertinent articles were reviewed and data on available outcomes synthesized.

RESULTS

Emergency conditions in surgery tax the patient's cardiovascular and respiratory systems, and fluid and electrolyte balance. The operative intervention itself leads to an inflammatory response and blood loss, thus adding to the physiological stress. NOTES provides a minimally invasive alternative access to the peritoneal cavity, avoiding abdominal wall incisions. A clear advantage to the patient is evident with the implementation of an endoscopic approach to deal with inadvertently displaced percutaneous endoscopic gastrostomy tubes and perforated gastroduodenal ulcer. The NOTES approach appears less invasive for patients with infected pancreatic necrosis, in whom it allows surgical debridement and avoidance of open necrosectomy. Transvaginal appendicectomy is the second most frequently performed NOTES procedure after cholecystectomy. The NOTES concept has provided a change in perspective for intramural and transmural endoscopic approaches to iatrogenic perforations during endoscopy.

CONCLUSION

NOTES approaches have been implemented in clinical practice over the past decade. Selected techniques offer reduced invasiveness for patients with intra-abdominal emergencies, and may improve outcomes. Steady future development and adoption of NOTES are likely to follow as technology improves and surgeons become comfortable with the approaches.

Development of a feasible transrectal natural orifice transluminal endoscopic surgery (NOTES®) approach in a cadaveric appendectomy model: anterior is better

BACKGROUND

The transrectal natural orifice transluminal endoscopic surgery (NOTES) approach is a potentially promising alternative to transgastric or transvaginal approaches for intraperitoneal procedures. However, whether the optimal transrectal approach for intraperitoneal surgery is anterior or posterior remains unknown. To evaluate this, a prospective comparison of anterior and posterior transrectal NOTES approaches in a cadaveric appendectomy model was performed.

METHODS

Operations were performed on human cadavers using a transanal endoscopic microsurgery (TEM) scope to assist with access and closure. Posterior access was achieved by tunneling cephalad through the retrorectal space into the peritoneal cavity. Anterior transrectal access was established through the rectal wall just above the peritoneal reflection. A dual-channel flexible endoscope was used to perform appendectomies. Rectotomies were closed using sutures or staples. Operative time, degree of laparoscopic assistance, complications, and leak-testing results were recorded.

RESULTS

This study investigated 10 cadavers with access and closure attempted using both anterior (n = 10) and posterior (n = 5) approaches, whereas appendectomies were performed using either an anterior (n = 8) or a posterior (n = 2) approach. The anterior approach required less time than the posterior approach for peritoneal access (4 ± 1 vs. 61 ± 14 min; p < 0.001), specimen extraction (2 ± 1 vs. 5 ± 1 min; p < 0.01), and the total operation (99 ± 35 vs. 176 ± 26 min; p = 0.02). A "pure" NOTES dissection was possible with the anterior approach using rigid transanal instruments for assistance. Dissection time, closure time, and the incidence of complications were similar between the two approaches. Leak testing of closures showed significant variability for all closure types.

CONCLUSION

Transrectal NOTES appendectomy is feasible in a cadaveric model using an anterior transrectal approach. This approach is technically easier, results in shorter operative times, and allows for a "pure" NOTES dissection compared with a posterior transrectal approach. Leak pressure testing of NOTES closures is unreliable in the cadaveric model.