Anorectal function: defecographic measurement in asymptomatic subjects.

A study of anorectal function during fluoroscopically monitored defecation was conducted in 32 asymptomatic subjects. Two observers independently measured various parameters on defecograms and reviewed video recordings during the subjects' squeezing, rest, and straining. There was a wide range of measurements for the anorectal angle, the position of the anorectal junction, perineal motility, and anal canal width. Interobserver variation of these measurements was large. In 17 subjects, both observers agreed that rectal emptying was incomplete. In 10 patients, there was agreement on the presence of rectal wall changes such as intussusception, rectocele, and mucosal prolapse. Defecographic measurements should be interpreted with caution and should not be used as the only criteria for treatment. Anatomic changes of the anorectal region during straining at defecation do not necessarily cause symptoms but may be a precursor of clinical disorders. Defecography is useful in the detection of these abnormalities.