Anorectal manometry and defecography in the diagnosis of fecal incontinence.

We carried out anorectal manometry and defecography prospectively in 43 consecutive patients with fecal incontinence. A subgroup of 17 patients with severe incontinence was identified radiologically by a short and incompletely closed anal canal. In these patients, the anal resting pressure was significantly lower than in the rest of the group (34.9 +/- 11.4 mm Hg versus 60.0 +/- 25.7 mm Hg, respectively; p less than 0.01). The anorectal angle did not change in 24 patients during squeezing, indicating a dysfunction of the puborectalis muscle. Manometric data did not differ between this subgroup and patients with a more acute anorectal angle during voluntary sphincter contraction. This indicates that the anal pressures recorded manometrically do not reflect the function of a muscular component that is important in the maintenance of fecal continence. We conclude that anorectal manometry and defecography are complementary diagnostic tools in the investigation of patients with fecal incontinence.