title: Endosonographic characteristics of the anal sphincter complex in primigravid Sri Lankan women.
abstract: OBJECTIVE
  To determine the endosonographic anatomy of the anal sphincter complex in primigravid Sri Lankan women.
  
  
  METHODS
  This is an observational study of 95 primigravid women admitted to an antenatal ward. They were examined using anal endosonography and data from subjects without sphincter injury were analyzed to describe anal sphincter morphology. Individual anal canal components were measured at defined levels, and the relationship of individual measurements with age and body mass index was calculated.
  
  
  RESULTS
  Ninety-three of 95 women had no anal sphincter damage. The puborectalis sling (mean 5.5 mm, S.D. 0.77) forms the upper most border of the sphincter complex. The mean width of the deep external sphincter was 4.3 mm (S.D. 0.61); that of the superficial external sphincter was 4.5 mm (S.D. 0.56); and that of the internal anal sphincter at the mid anal canal was 2.1 mm (S.D. 0.21). The intersphincteric space (mean 2.1 mm, S.D. 0.26) could be distinguished sonographically in all subjects. The mean width of the anterior ring of the subcutaneous component was 3.8 mm (S.D. 1.01). The perineal body was sonographically identified in 60%.
  
  
  CONCLUSIONS
  A set of normal values for the anal sphincter components in Sri Lankan primigravid women was established.
authors.affiliation: University Department of Obstetrics and Gynecology, North Colombo Teaching Hospital and University of Kelaniya, Sri Lanka. mayooran28@hotmail.com
authors.forename: V
authors.initials: V
authors.lastname: Mayooran
authors.forename: K I
authors.initials: KI
authors.lastname: Deen
authors.forename: P S
authors.initials: PS
authors.lastname: Wijesinghe
authors.forename: A
authors.initials: A
authors.lastname: Pathmeswaran
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000293:injuries; D036861:Delivery, Obstetric; D019160:Endosonography; D005260:Female; D020073:Gravidity; D006801:Humans; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012016:Reference Values; D013188:Sri Lanka; D016216:Ultrasonography, Prenatal