title: Sonographic visualization of the rectoanal inhibitory reflex in children suspected of having Hirschsprung disease: a pilot study.
abstract: OBJECTIVE
  To date, for detection of the absence of peristalsis in children with chronic constipation and a suspicion of Hirschsprung disease (HD), children have been investigated with a contrast enema. If the radiographic investigation is inconclusive, anometry and a rectal biopsy are performed. A new noninvasive real-time sonographic method for examination of the rectoanal inhibitory reflex (RAIR) was compared with anometry.
  
  
  METHODS
  The rectum and anal canal of children were visualized transperineally on sonography. The RAIR was elicited by injecting water into the rectum, and the events in the bowel were recorded on video for offline analysis.
  
  
  RESULTS
  Injection of water initiated a peristaltic wave that moved the rectal contents into the proximal part of the anal canal in healthy children. Among 28 children with suspected HD, 3 showed aganglionosis in their biopsy samples. These 3 children lacked the RAIR according to both sonography and anometry. Both methods had a negative predictive value of 100%. In 17 children, the RAIR was present according to both sonography and anometry, and all of these children had normal histologic findings. In 8 children, sonography did not show the reflex despite normal histologic findings; in 2 of these, the quality of the investigation made the evaluation uncertain.
  
  
  CONCLUSIONS
  This pilot study indicates that in children with chronic constipation, a transperineal sonographic examination of the RAIR is comparable to anometry and can facilitate the diagnose of HD.
authors.affiliation: Department of Obstetrics and Gynecology, Clinical Sciences Lund, Lund University, Sweden. ann-kristin.orno@med.lu.se
authors.forename: Ann-Kristin
authors.initials: AK
authors.lastname: Ornö
authors.forename: Håkan
authors.initials: H
authors.lastname: Lövkvist
authors.forename: Karel
authors.initials: K
authors.lastname: Marsál
authors.forename: Kristina Vult
authors.initials: KV
authors.lastname: von Steyern
authors.forename: Einar
authors.initials: E
authors.lastname: Arnbjörnsson
mesh_terms: D001003:Anal Canal / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003248:Constipation / Q000175:diagnosis*; D004733:Enema / Q000379:methods; D005260:Female; D006627:Hirschsprung Disease / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010865:Pilot Projects; D012007:Rectum / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography