Sonographic visualization of the rectoanal inhibitory reflex in children suspected of having Hirschsprung disease: a pilot study.

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.