title: Radiologic and anatomic study of the extraperitoneal space associated with the rectum.
abstract: OBJECTIVE
  The objective of our study was to clarify the anatomic and radiologic features of the extraperitoneal fasciae and fascial spaces associated with the rectum.
  
  
  METHODS
  Fourteen embalmed cadavers were studied: two for gross anatomy; six for sectional anatomy, of which two underwent histologic study; and six for space perfusion study. These examinations were followed by CT and cross dissection to observe the pelvic extraperitoneal fasciae and the role of the fasciae in the anatomic subdivision and communication of the fascial spaces. Eighty healthy subjects underwent CT or MRI to identify the imaging characteristics of the pelvic fasciae.
  
  
  RESULTS
  Cadaver dissection and histologic study revealed a distinct sheath consisting of dense connective tissue encasing the rectum and surrounding adipose tissue like a sleeve that divided the rectal extraperitoneal space into the perirectal space and pararectal space. Perfusion studies showed communication between the pararectal spaces and the vesical extraperitoneal space anteriorly and the anterior pararenal space superiorly, but not with the perirectal space. In healthy subjects, both CT (95.0%) and MRI (97.5%) showed a circular or linear structure representing the rectal fascia outside the rectum encasing the rectum and its surrounding adipose tissue.
  
  
  CONCLUSIONS
  The extraperitoneal segment of the rectum and its surrounding adipose tissue are encased by a fascia, like a sleeve, that can be seen on CT and MRI in healthy populations. The fascia divides the rectal extraperitoneal space into the perirectal space and pararectal space, and it may prevent lesions of the rectum from spreading to other pelvic extraperitoneal spaces.
authors.affiliation: Department of Radiology, Xuan-Wu Hospital, Capital University of Medical Sciences, 45 Chang-Chun St., Xuanwu District, Beijing 100053, People's Republic of China. cnddcndd@yahoo.com
authors.forename: Nan
authors.initials: N
authors.lastname: Chen
authors.forename: Peng Qiu
authors.initials: PQ
authors.lastname: Min
authors.forename: Zai Yi
authors.initials: ZY
authors.lastname: Liu
authors.forename: Bing
authors.initials: B
authors.lastname: Wu
authors.forename: Kai Qing
authors.initials: KQ
authors.lastname: Yang
authors.forename: Chun Yan
authors.initials: CY
authors.lastname: Lu
mesh_terms: D034841:Abdominal Cavity / Q000033:anatomy & histology*; D000273:Adipose Tissue / Q000033:anatomy & histology; D002102:Cadaver; D003287:Contrast Media; D003430:Cross-Sectional Studies; D005205:Fascia / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008279:Magnetic Resonance Imaging; D008297:Male; D012007:Rectum / Q000033:anatomy & histology*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide