title: Perineal and pelvic anatomy of extralevator abdominoperineal excision for rectal cancer: cadaveric dissection.
abstract: BACKGROUND
  Circumferential margin positivity and tumor perforations are the main reasons for the poor oncological outcome following standard abdominoperineal excision for low rectal cancer. The extralevator abdominoperineal excision approach has been developed to avoid "coning down" or "surgical waisting"; however, surgical education in this area has been neglected.
  
  
  OBJECTIVE
  This study aims to define correct surgical anatomical planes for extralevator abdominoperineal excision and show the differences in excision planes between standard and extralevator abdominoperineal excision.
  
  
  METHODS
  Macroscopic surgical dissections were performed in a clinical anatomy laboratory. The dissections were recorded as video clips.
  
  
  METHODS
  In accordance with the surgical technique of extralevator abdominoperineal excision, abdominal and then perineal dissections were performed on 1 female and 5 male cadavers. Neurovascular, muscular, and fascial structures located in or near the excision field were carefully revealed.
  
  
  RESULTS
  The surgical planes of extralevator abdominoperineal excision, which widen the tumor-free margins and prevent inadvertent bowel perforation, are described in this step-by-step anatomical dissection study. Within the surgical excision planes, sacral vessels and sympathetic chains form a neurovascular network at the level of the sacrococcygeal joint. Although pelvic autonomic plexuses were away from the lateral incision line, their branches extending to urogenital organs were very close to the anterolateral dissection line. Perineal dissection showed that the internal pudendal vessels and pudendal nerve were close to the lateral excision plane. The superficial transverse perineal muscle and perineal body were the most important landmarks to determine the anterior boundary of dissection.
  
  
  CONCLUSIONS
  The study focused on the perineal dissection of extralevator abdominoperineal excision.
  
  
  CONCLUSIONS
  Successful extralevator abdominoperineal excision crucially depends on an accurate knowledge of surgical anatomical planes.
authors.affiliation: Department of Anatomy, Faculty of Medicine, Ankara University, Ankara, Turkey.
authors.forename: Halil İbrahim
authors.initials: Hİ
authors.lastname: Açar
authors.forename: Mehmet Ayhan
authors.initials: MA
authors.lastname: Kuzu
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology* / Q000601:surgery; D000328:Adult; D000368:Aged; D002102:Cadaver; D003107:Colorectal Surgery / Q000379:methods*; D004210:Dissection; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010502:Perineum / Q000033:anatomy & histology* / Q000601:surgery; D012004:Rectal Neoplasms / Q000601:surgery; D014741:Video Recording