A clinical evaluation of anorectal pressure studies in the diagnosis of Hirschsprung's disease.

Stimulation of the rectum by stretch results, in the normally innervated bowel, in the reflex relaxation of the internal anal sphincter. The absence of this rectosphincteric reflex in Hirschsprung's disease forms the basis of a simple and safe diagnostic test. Our experience over two years using a simplified air-filled pressure probe system is described, based on the examination of 267 infants and children with abnormal bowel function, of whom 114 were suffering from Hirschsprung's disease.A review of the last 100 consecutive patients examined shows an overall diagnostic reliability of 85%. This was of the same order as that of a barium enema in these patients, and indeed of obtaining the correct diagnosis on the first rectal biopsy. It has proved easier to exclude the disease (90.8%) than to confirm its presence (74.3%), and has been found to be more reliable than the barium enema in the diagnosis of ultrashort segment disease. The commoner pitfalls in the interpretation of the trace are described. We consider that this investigation justifies a place in the routine investigation of Hirschsprung's disease alongside the barium enema and rectal biopsy, and is of particular value as a simple screening test in outpatients.