title: Transanal natural orifice transluminal endoscopic surgery total mesorectal excision in animal models: endoscopic inferior mesenteric artery dissection made easier by a retroperitoneal approach.
abstract: OBJECTIVE
  We report the performance of natural orifice transluminal endoscopic surgery (NOTES) low anterior resection in animals using transanal total mesorectal excision (TME) with laparoscopic assistance and endoscopic inferior mesenteric artery (IMA) dissection.
  
  
  METHODS
  Four pigs weighing 45 kg each, and one dog weighing 25 kg, underwent surgery via a transanal approach. The rectum was occluded transanally using a purse-string suture, approximately 3-4 cm from the anal verge. The rectal mucosa was incised circumferentially just distal to the purse-string. A SILS or GelPOINT port was inserted transanally. Transanal TME was assisted by laparoscopy and proceeded up to the peritoneal reflection. More proximal dissection, including IMA dissection, was performed along the retroperitoneal avascular plane by endoscopy alone and facilitated by CO2 insufflation. The IMA was clipped and divided endoscopically. The mobilized rectosigmoid were exteriorized transanally and transected. A colorectal anastomosis was performed using a circular stapler with a single stapling technique.
  
  
  RESULTS
  Endoscopic dissection of the IMA was successful in all five animals. The mean operation time was 125 minutes (range, 90-170 minutes). There were no intraoperative complications or hemodynamic instability. The mean length of the resected specimen was 14.4 cm (range, 12-16 cm).
  
  
  CONCLUSIONS
  A NOTES retroperitoneal approach to the IMA with CO2 insufflation and intact peritoneal covering overcame the difficulties of retraction and exposure of endoscopic dissection in animals.
authors.affiliation: Department of Surgery, Kyung Hee University School of Medicine, Seoul, Korea.
authors.forename: Sun Jin
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Dae Kyung
authors.initials: DK
authors.lastname: Sohn
authors.affiliation: Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Tae Young
authors.initials: TY
authors.lastname: Chang
authors.affiliation: Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Korea.
authors.forename: Yunho
authors.initials: Y
authors.lastname: Jung
authors.affiliation: Department of Surgery, St. Vincent's Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Chung-Cheong Surgery Clinic, Daejeon, Korea.
authors.forename: Young Ill
authors.initials: YI
authors.lastname: Kim
authors.affiliation: Department of Surgery, Kangbuk Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Ho-Kyung
authors.initials: HK
authors.lastname: Chun
keywords: Inferior mesenteric artery; Natural orifice transluminal endoscopic surgery; Retroperitoneal approach; Total mesorectal excision