title: Endosonographic evaluation of anal sphincters in healthy children.
abstract: OBJECTIVE
  To describe the endosonographic anatomy of anal sphincters in healthy children and to evaluate the reproducibility of sphincter thickness measurements.
  
  
  METHODS
  Forty-five healthy children with median age of 3.6 years (range, 1.0-14.5 years) were studied while under general anesthesia for minor surgery. Anal endosonography was performed with a 7- to 10-MHz rotating transducer with a diameter of 19 mm. The internal anal sphincter (IAS) and the external anal sphincter (EAS) were assessed by 2 independent observers.
  
  
  RESULTS
  IAS and EAS were identified in all children. The mean thickness of IAS and EAS were 1.3 mm and 5.3 mm, respectively. Identification of the inner and outer border of IAS was difficult, especially in children younger than 3 years. The thickness of EAS was easier to assess, and the interrater reliability for EAS thickness measurements was excellent. EAS thickness was positively correlated with the children's age. Reflectivity varied within the EAS with frequent hyporeflective areas.
  
  
  CONCLUSIONS
  Anal endosonography provided visualization of the IAS and EAS in children. Assessment of exact IAS thickness was difficult, especially in the youngest children. Mean EAS thickness was 5.3 mm, increasing with age. Hyporeflective areas of the intact EAS should not be misinterpreted as sphincter defects.
authors.affiliation: Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Rehman
authors.forename: Kjetil Juul
authors.initials: KJ
authors.lastname: Stensrud
authors.forename: Lars
authors.initials: L
authors.lastname: Mørkrid
authors.forename: Kristin
authors.initials: K
authors.lastname: Bjørnland
authors.forename: Ragnhild
authors.initials: R
authors.lastname: Emblem
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001003:Anal Canal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D019160:Endosonography; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012737:Sex Factors