Anorectal function and continence mechanisms in childhood encopresis.

We compared anorectal sensory and motor functions, expulsion dynamics, and continence mechanisms in 50 children with encopresis and 21 healthy control children. When expulsion dynamics were studied, 43% of boys with encopresis inappropriately contracted the muscles near the anal canal compared with 10% of girls with encopresis (p greater than 0.05) and 10% of control children of both sexes (p less than 0.05). In contrast to previous studies we demonstrated no abnormalities of thresholds of conscious rectal sensation or internal anal sphincter relaxation. In addition, children with encopresis had no demonstrable abnormalities of rectosphincteric continence mechanisms or strength of external anal sphincter contraction. We conclude that a significant number of boys with encopresis have abnormal anorectal expulsion dynamics, which may contribute to chronic fecal retention and incontinence. Abnormalities of anorectal sensory and motor function and of rectosphincteric continence mechanisms do not seem to be important in the pathogenesis of childhood encopresis.