Patients with acquired megacolon suffer from a double dysfunction: a) dilatation and inertia of the colon and b) low rectal sensitivity, inhibition of the anorectal reflex and achalasia. There are several methods to evaluate dysfunctions in defecation. However, from an anal physiology point of view, the most appropriate methods are: rectal sensitivity measurement with an air baloon, anorectal reflex verification and quantitative defecography. Our objective was to compare these methods in 29 patients with severe acquired megacolon. The results depicted that the anorectal reflex was absent in 79% of the cases and the rectal sensitivity was reduced in all cases. However, there was no correlation between the inhibition of the anorectal reflex, loss of sensitivity and defecography. The conclusion was that quantitative defecography was a more reliable method for these patients.
Rectal sensibility; inhibitory reflex; defecography; megacolon
