title: Changes in anal anatomy following vaginal delivery revealed by anal endosonography.
abstract: OBJECTIVE
  To investigate changes in anal canal anatomy following vaginal delivery in women without apparent sphincter injury.
  
  
  METHODS
  Prospective controlled observational study.
  
  
  METHODS
  District general hospital.
  
  
  METHODS
  Consecutive parous and nulliparous women attending a gynaecology outpatient clinic.
  
  
  METHODS
  All women were examined using anal endosonography, and parous subjects without apparent sphincter injury compared with age-matched nulliparous controls to determine any differences in general anal canal morphology.
  
  
  METHODS
  Individual anal canal components were measured at defined levels and subjects compared with controls.
  
  
  RESULTS
  Twenty-one of 54 parous women had no anal sphincter scar. Compared with nulliparous women, they had significant anterior sphincter thinning (mean 3.7 mm vs 4.6 mm, P< 0.01) in association with lateral external sphincter thickening (mean 7.0 mm vs 4.4 mm, P<0.01), and longitudinal muscle thickening (mean 2.8 mm vs 2.1 mm, P< 001).
  
  
  CONCLUSIONS
  Specific changes in anal morphology have been demonstrated following vaginal delivery in women without apparent sphincter injury.
authors.affiliation: Intestinal Imaging Centre, Department of Obstetrics and Gynaecology, Northwick Park and St. Mark's NHS Hospitals Trust, Harrow, Middlesex, UK.
authors.forename: A
authors.initials: A
authors.lastname: Frudinger
authors.forename: S
authors.initials: S
authors.lastname: Halligan
authors.forename: C I
authors.initials: CI
authors.lastname: Bartram
authors.forename: J A
authors.initials: JA
authors.lastname: Spencer
authors.forename: M A
authors.initials: MA
authors.lastname: Kamm
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D036861:Delivery, Obstetric; D019160:Endosonography; D005260:Female; D006801:Humans; D008875:Middle Aged; D010298:Parity; D011247:Pregnancy; D011446:Prospective Studies