title: Identification of the retrotrigonal layer as a key anatomical landmark during robotically assisted radical prostatectomy.
abstract: OBJECTIVE
  To define the gross and microscopic anatomy, and the surgical significance, of the newly described retrotrigonal layer of the bladder neck, as an aid during robotic radical prostatectomy (RRP).
  
  
  METHODS
  The data for this study were obtained from five fresh cadaveric dissections and 100 consecutive RRPs. Five male cadavers with no previous pelvic or urethral surgery were dissected to expose the posterior bladder neck and identify the retrotrigonal layer. This same layer was reproducibly identified in all 100 RRPs. The gross appearance of this layer, and its relationship to neighbouring structures, was documented using still photographs and intraoperative video. The microscopic composition of this layer was assessed using routine haematoxylin and eosin stains, and special staining for smooth muscle (desmin), neural tissue (S-100), and elastin.
  
  
  RESULTS
  Grossly, the retrotrigonal layer is a well-defined midline strip located posterior to the bladder neck, that extends from the trigone (superiorly) to the base of the prostate (inferiorly). Microscopically, this layer was predominantly composed of smooth muscle with intervening connective tissue. The retrotrigonal layer serves as a key anatomical landmark to facilitate posterior prostatic dissection, particularly in men with large prostates, prominent median lobes, or previous transurethral prostatic surgery. Further, in our practice, this layer marks the posterior limit of dissection in which electrocautery is still used. Finally, the retrotrigonal layer serves to buttress the posterior layer of the urethrovesical anastomosis.
  
  
  CONCLUSIONS
  The retrotrigonal layer is a key landmark during the posterior bladder neck dissection in the antegrade technique of RRP.
authors.affiliation: Department of Urology, The New York-Presbyterian Hospital, Weill Medical College of Cornell University, New York, NY 10021, USA. akt2001@med.cornell.edu
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Tewari
authors.forename: Assaad
authors.initials: A
authors.lastname: El-Hakim
authors.forename: Sandhya
authors.initials: S
authors.lastname: Rao
authors.forename: Jay D
authors.initials: JD
authors.lastname: Raman
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D006801:Humans; D008297:Male; D008875:Middle Aged; D011468:Prostatectomy / Q000295:instrumentation / Q000592:standards*; D011471:Prostatic Neoplasms / Q000473:pathology / Q000601:surgery*; D012371:Robotics; D001743:Urinary Bladder / Q000033:anatomy & histology*