Comparison of Transrectal NOTES® Approaches in a Cadaveric Appendectomy Model: Anterior Is Better

Byron F Santos, MD, Eric S Hungness, MD, Nathaniel J Soper, MD, Anne-Marie Boller, MD. Northwestern University Department of Surgery, Chicago, IL

Introduction: A transrectal NOTES approach is a potentially promising alternative to transgastric or transvaginal approaches for intraperitoneal procedures. Although both anterior and posterior transrectal approaches have been described in pre-clinical models, the optimal transrectal approach for intraperitoneal surgery is unknown. To evaluate this, we performed a prospective comparison of anterior and posterior transrectal NOTES approaches in a cadaveric appendectomy model.

Methods: Operations were performed on fresh-frozen, then thawed, human cadavers. A transanal endoscopic microsurgery (TEM) scope was used to access the rectum and incise the rectal wall. Posterior access was performed by tunneling cephalad through the retrorectal space, using a combination of rigid instruments and a flexible endoscope through the TEM scope. The peritoneal cavity was entered by the flexible endoscope through a retroperitoneal incision made under laparoscopic guidance. Alternatively, anterior transrectal access was established proximal to the peritoneal reflection using rigid instruments through the TEM scope. Appendectomies were performed using a dual-channel, flexible endoscope through either the anterior or posterior transrectal approach, with laparoscopic assistance as needed. The rectal incisions were closed using the TEM scope. Outcomes included operative times, degree of laparoscopic assistance, complications, and leak-testing using intraoperative insufflation and an ex-vivo saline leak test.

Results: A total of 8 male cadavers were studied. Access and closure were attempted using both anterior (n=8) and posterior (n=5) approaches, while appendectomies were performed using either an anterior (n=6) or posterior (n=2) approach. Peritoneal access time (4 ± 1 v. 61 ± 14 minutes, p < .001), specimen extraction time (2 ± 1 v. 5 ± 1 minutes, p = .002), and total operative time (107 ± 38 v. 176 ± 26 minutes, p = .03) were significantly shorter for anterior versus posterior approaches, respectively. A “pure” NOTES dissection was possible with the anterior approach by using rigid transanal instruments for assistance, while the posterior approach required laparoscopic assistance. Dissection time (54 ± 20 v. 61 ± 28 minutes, p = .24), closure time (33 ± 11 v. 27 ± 3 minutes, p = .15), intraoperative insufflation testing results (63% v. 80% success, p = 0.5), and the incidence of complications related to access (0/8 v. 1/5, p = 0.19) or dissection (3/6 v. 1/2, p = 1) were similar between anterior and posterior approaches, respectively. Saline leak testing of closures showed significant variability for all closure types (anterior, posterior, and a hand-sewn control).

Conclusion: Transrectal NOTES appendectomy is feasible in a cadaveric model using an anterior transrectal approach. An anterior transrectal approach is technically easier, results in shorter operative times, and allows for a “pure” NOTES dissection compared to a posterior transrectal approach. The strength of NOTES closures by leak-pressure testing cannot be reliably quantified in the cadaveric model.