EUS in localizing safe alternate access sites for natural orifice transluminal endoscopic surgery: initial experience in a porcine model

Background: Most natural orifice transluminal endoscopic surgery (NOTES) procedures have been performed through the anterior stomach wall, based on the established safety of PEG placement. This approach does not afford mechanically efficient access to all anatomic areas of interest. Objective: To assess the utility of EUS in identifying safe alternate access sites for NOTES. Design: Nonsurvival animal experiment. Methods: Thirty-two EUS-guided access procedures were performed through the antrum, the posterior stomach wall, or the rectum of 12 pigs. Sixteen safe-access procedures (SAP) used sonographic guidance to achieve safe intraperitoneal access by avoiding extraluminal organs and vessels during the initial NOTES puncture. Sixteen unsafe-access procedures (UAP) evaluated potential complications of blind access by performing a standard NOTES puncture at sites adjacent to critical extraluminal structures identified by EUS. Access was achieved by using a similar technique for both SAPs and UAPs. Baseline and completion laparotomies were performed. Results: All 16 UAPs resulted in clinically relevant complications, such as liver laceration and iliac artery injury. In contrast, 13 SAPs were without complication. The 3 complications in the SAP group occurred with transrectal access and consisted of 2 minor complications and a small-bowel perforation. Conclusions: Blind NOTES access through the antrum, posterior stomach wall, and rectum could result in catastrophic complications. In contrast, EUS-guided access through these sites substantially reduced but did not completely eliminate this risk. EUS appears promising as an adjunct to NOTES access, particularly as more experience is gained in definitively excluding the presence of at-risk extraluminal structures.