Quantitative analysis of anorectal pressures in Hirschsprung's disease.

Anorectal motility was investigated in 146 children with Hirschsprung's disease and 89 normal control subjects. Pressures were recorded in the rectum and anal canal at rest and during rectal distention. The rectoanal inhibitory reflex was absent in all but four patients. Intraluminal rectal pressure was higher than normal (16.5 vs. 14.6 cm H2O, P less than 0.03), with more frequent (41 per cent vs. 18 per cent, P less than 0.01) pressure waves. In the upper anal canal, there were more frequent (62 per cent vs. 18 per cent, P less than 0.001) spontaneous variations of pressure of lower frequency (9.5 vs. 12.8 cycles/min P less than 0.001) and greater amplitude (5.2 vs. 3.6 cm H2O, P less than 0.001) than normal. The rectoanal contractile reflex occurred in 47 per cent of the patients but in only 21 per cent of the control subjects (P less than 0.001). Aganglionosis was associated with the presence of a rectoanal inhibitory reflex in three patients. This study confirms the value of anorectal manometry in diagnosing Hirschsprung's disease in a large group of patients, and demonstrates other abnormalities that may be useful in cases in which histologic and manometric data are in conflict.